JP6874211B2 - Eccentricity measuring device and method - Google Patents

Description

The present invention relates to an eccentricity measuring device and a method, and particularly relates to a technique for measuring an eccentricity amount of an actual curvature center position with respect to a design curvature center position of an optical surface to be measured of a lens.

Conventionally, as an eccentricity measuring device of this kind, those described in Patent Documents 1 to 3 are known.

The eccentricity measuring machine described in Patent Document 1 causes a vertical light beam to be incident on a lens surface (optical surface to be measured) to be measured by a lens, and returns the reflected light beam in the opposite direction to the incident light beam, and the light beam is generated. A method of measuring eccentricity from the amount of deflection of the imaging position on the position sensor (hereinafter, this method is referred to as "autocollimation method") is used, and in particular, the centers of curvature of the first and second surfaces of the lens are the same. In order to enable eccentricity measurement of a special meniscus lens, the irradiation light is focused at a position deviated from the center of curvature of the first surface in the optical axis direction, and the light beam reflected by the first surface and reflected by the second surface. Make sure that the light path is different from that of the light beam. Then, the luminous flux reflected and returned from the first surface (optical surface to be measured) is imaged as a point image on the position sensor, and the luminous flux reflected and returned from the second surface is a blurred image on the position sensor. The image is formed so that the light flux reflected on which surface can be distinguished.

The interferometer described in Patent Document 2 has interference fringes of an optical path including an i-plane (a specific optical surface to be measured) obtained by passing a light beam through a lens placed in the interferometer optical path, and an eccentricity obtained by calculation. The eccentricity of the i-plane of the lens is obtained from the data related to the above.

The lens shape measuring device described in Patent Document 3 has a light source unit that selectively switches between coherent light and low coherence light to emit light, and when the light is switched to coherent light, the coherent light is emitted from the coherent light by a reference lens. The measured light beam is focused on the center of curvature of the test surface of the test lens and irradiates the test surface of the test lens, and the reflected light beam from the test lens and the measured light beam reflected by the optical surface of the reference lens. An interference fringe image is acquired by interfering with (reference light beam). Then, by obtaining the number of acquired interference fringe images and the change in the phase of the interference fringe images by image processing, the positional relationship between the condensing position of the measured light beam and the surface top of the test surface, or the condensing position and the subject. The positional relationship of the inspection surface with the center of curvature and the amount of eccentricity of the inspection surface with respect to the measurement optical axis of the measurement optical system are obtained. As a result, the driving amount of the measurement optical system for aligning the optical axis of the measurement optical system including the reference lens with the test surface and the condensing position coincide with the surface apex or the center of curvature of the test surface. The driving amount of the measuring optical system to be driven is obtained, and the measuring optical system is driven by these driving amounts to align the measuring optical system with respect to the test surface of the test lens. The lens shape measuring device described in Patent Document 3 switches from coherent light to low coherence light when the alignment between the measurement optical system and the test surface of the test lens is completed, and the wall thickness and surface roughness of the test lens are roughened. Now, measure the lens shape such as surface accuracy.

Japanese Unexamined Patent Publication No. 4-106447 Japanese Unexamined Patent Publication No. 2001-147174 Japanese Unexamined Patent Publication No. 2014-2026

The eccentricity measuring machine described in Patent Document 1 shifts the focusing point of the irradiation light from the center of curvature of the optical surface to be measured in the optical axis direction, so that an error occurs in the measurement of the amount of eccentricity of the optical surface to be measured. There's a problem.

The interference measuring machine described in Patent Document 2 has a problem that if the amount of eccentricity of the optical surface to be measured of the lens is large, the density of the interference fringes increases and it becomes difficult to analyze the interference fringes.

Further, although Patent Document 3 describes that the amount of eccentricity of the test surface of the test lens with respect to the measurement optical axis of the measurement optical system is obtained, the actual position of the center of curvature of the test surface of the test lens with respect to the design There is no description to determine the amount of eccentricity at the center of curvature of the surface to be inspected. The lens shape measuring device described in Patent Document 3 obtains the number of interference fringe images and the phase change of the interference fringe images by image processing, and obtains the optical axis between the measurement optical axis of the measurement optical system and the surface to be inspected. The driving amount of the measuring optical system for matching and the driving amount of the measuring optical system for matching the condensing position with the surface apex or the center of curvature of the test surface are obtained, and the test surface of the test lens is obtained. The amount of eccentricity is not measured by obtaining the actual position of the center of curvature of the test surface with respect to the position of the center of curvature in the design of.

The present invention has been made in view of such circumstances, and is an eccentricity measuring device capable of accurately measuring the amount of eccentricity of the actual curvature center position with respect to the design curvature center position of the optical surface to be measured of the lens. And to provide a method.

The invention according to one aspect for achieving the above object is an eccentricity measuring device for measuring the amount of eccentricity of the optical surface to be measured of a lens, and a light source that emits measurement light and a light source that collects the measurement light. The measurement optical system, which is a measurement optical system having a bending portion that bends the optical path of the measurement light with the first optical system, and a bending angle of the optical path of the measurement light are changed by using the bending portion to collect the measurement light. A scanning control unit that scans the surface, a detection unit that detects intensity information of the reflected measurement light that is the measurement light reflected by the optical surface to be measured, and a measurement unit that measures the amount of eccentricity of the optical surface to be measured. , The detection unit detects the strength information at each of the plurality of bending angles when the bending angle is changed by the scanning control unit, and the measuring unit detects the strength information at each of the plurality of bending angles and the bending angle of the bending portion. Based on the information, the amount of eccentricity of the optical surface to be measured is measured.

According to one aspect of the present invention, the bending angle of the optical path of the measurement light is changed by using the bending portion of the measurement optical system, and the condensing position of the measurement light is scanned. Intensity information at each of a plurality of bending angles of the reflected measurement light, which is the measurement light reflected by the optical surface to be measured during scanning of the condensing position of the measurement light, is detected. Then, the amount of eccentricity of the optical surface to be measured is measured based on the strength information at each of the plurality of bending angles and the bending angle information of the bent portion. Since the focused position of the measurement light is scanned in this way, the return light on the optical surface to be measured can be captured well, and the eccentricity of the optical surface to be measured is based on the bending angle information when the intensity information becomes large. The amount can be measured.

In the eccentricity measuring device according to another aspect of the present invention, the focal length of the first optical system is variable, and the focal length of the first optical system is changed to change the focusing position of the measurement light. .. As a result, the condensing position of the measurement light can be made to match the surface (scanning surface) where the center of curvature of the optical surface to be measured of the lens exists.

In the eccentricity measuring device according to still another aspect of the present invention, the first optical system has a first lens, and the focal length of the first lens is changed by electrical control. By changing the focal length of the first lens, the focusing position of the measurement light is changed. Since this first lens does not move in the optical axis direction, it is possible to minimize the deviation of the optical axis of the measurement light when the focusing position is changed by the first lens.

In the eccentricity measuring apparatus according to still another aspect of the present invention, the measuring optical system is a second optical system that changes the maximum value of the refractive power of the first optical system and the minimum value of the refractive power of the first optical system. It is preferable to have.

In the eccentricity measuring device according to still another aspect of the present invention, it is preferable that the measurement light emitted from the light source enters the first optical system via the bent portion.

In the eccentricity measuring device according to still another aspect of the present invention, it is preferable that the measurement light emitted from the light source is incident on the bent portion via the first optical system.

In the eccentricity measuring device according to still another aspect of the present invention, the collimator lens that makes the measurement light parallel light is provided, and the measurement light emitted from the light source is incident on the first optical system via the collimator lens. Is preferable.

The eccentricity measuring device according to still another aspect of the present invention includes a first demultiplexing unit that separates the optical path of the measurement light and the optical path of the reflection measurement light, and the detection unit is the reflection measurement light emitted from the first demultiplexing unit. Is preferable to detect.

In the eccentricity measuring device according to still another aspect of the present invention, the detection unit detects the light amount of the reflection measurement light as intensity information, and the measurement unit takes the maximum value of the light amount of the reflection measurement light. It is preferable to measure the amount of eccentricity of the optical surface to be measured by using the bending angle information of. This is because when the amount of reflected measurement light reaches the maximum value, the position where the measurement light is focused becomes the actual center position of curvature of the optical surface to be measured.

In the eccentricity measuring device according to still another aspect of the present invention, a second demultiplexing portion that demultiplexes the reference light from the measurement light and a confluence portion that combines the reflection measurement light and the reference light are provided as a light source. Is a low coherence light source that emits low coherence light as measurement light, and the detection unit preferably detects the amount of the combined wave light combined at the combined wave portion as intensity information.

In the eccentricity measuring device according to still another aspect of the present invention, a second demultiplexing portion that demultiplexes the reference light from the measurement light and a confluence portion that combines the reflection measurement light and the reference light are provided as a light source. Is a low coherence light source that emits low coherence light as measurement light, and it is preferable that the detection unit detects the distribution of the amount of the combined wave light combined at the combined wave portion as intensity information.

In the eccentricity measuring device according to still another aspect of the present invention, it is preferable to include an optical path length adjusting unit that adjusts the optical path length of one of the reflected measurement light and the reference light before being combined by the combining unit. ..

The invention according to still another aspect is an eccentricity measuring device for measuring the amount of eccentricity of the optical surface to be measured of a lens, which is a low coherence light source that emits low coherence light as measurement light and a low coherence light for measuring light. The demultiplexing unit that demultiplexes the light and the reference light, the measurement optical system that has a first optical system that changes the focusing position of the measurement light and the scanning unit, and the scanning unit are controlled to change the focusing position of the measurement light. Detection that detects the intensity information of the scanning control unit, the combined wave unit that combines the reflected measurement light and the reference light, which are the measurement light reflected by the optical surface to be measured, and the combined wave light combined by the combined wave unit. The detection unit includes a unit and a measurement unit that measures the amount of eccentricity of the optical surface to be measured, and the detection unit can be used to position a plurality of measurement light collection positions when the measurement light collection position is changed by the scanning unit. The intensity information in each is detected, and the measuring unit measures the amount of eccentricity of the optical surface to be measured based on the intensity information at each of the condensing positions of the plurality of measurement lights and the scanning information by the scanning unit.

According to still another aspect of the present invention, the intensity information of the combined light of the reflected measurement light reflected on the optical surface to be measured and the reference light is obtained by using the measurement light and the reference light demultiplexed from the low coherence light. Since it is detected, it is possible to prevent the reference light from interfering with the measurement light reflected on the optical surface having the same center of curvature position as the optical surface to be measured or the optical surface having a narrow air distance from the optical surface to be measured. This makes it possible to satisfactorily detect the combined light (interference light) between the measurement light and the reference light reflected by the optical surface to be measured.

In the eccentricity measuring device according to still another aspect of the present invention, it is preferable to include an optical path length adjusting unit that adjusts the optical path length of one of the reflected measurement light and the reference light before being combined by the combining unit. .. As a result, the optical path length of one of the measurement light and the reference light demultiplexed from the low coherence light is adjusted according to the position of the optical surface to be measured among the plurality of optical surfaces of the lens, thereby being measured. The measurement light reflected on the optical surface having the same center of curvature position as the optical surface or the optical surface having a narrow air distance from the optical surface to be measured can be prevented from interfering with the reference light, and is reflected by the optical surface to be measured. It is possible to satisfactorily detect the combined light of the measurement light and the reference light.

The eccentricity measuring device according to still another aspect of the present invention includes a low coherence light source that emits low coherence light, a demultiplexing portion that demultiplexes the low coherence light into measurement light and reference light, and a plurality of optics of the lens. Of the surfaces, the objective lens that collects the measurement light on the scanning surface where the design curvature center position of the optical surface to be measured exists, and the position where the measurement light is collected by the objective lens are moved on the scanning surface. Of the measurement optical system having a scanning unit, the combiner that combines the measurement light reflected by the optical surface of the lens and the reference light, and the measurement light and the reference light before being combined by the combiner. An optical path length adjusting unit that adjusts one of the optical path lengths according to the position of the optical surface to be measured, and a phase modulation unit that phase-modulates one of the measurement light and the reference light before being combined by the combining unit. The position of the center of curvature of the optical surface to be measured with respect to the design center of curvature based on the detection unit that detects the combined light combined by the combiner, the detection output obtained from the detection unit, and the scanning information by the scanning unit. It is provided with a measuring unit for measuring the amount of eccentricity.

According to still another aspect of the present invention, among the plurality of optical surfaces of the lens, another optical surface is used to collect the measurement light on the scanning surface where the design curvature center position of the optical surface to be measured exists. It is possible to reduce the influence of the measurement light reflected by. Further, when the condensing position of the measurement light is moved on the scanning surface and the condensing position of the measurement light is moved to the actual center position of curvature of the optical surface to be measured, the return light on the optical surface to be measured is captured well. Can be done. The amount of eccentricity of the optical surface to be measured can be measured based on the scanning information at this time. Further, the measurement light and the reference light demultiplexed from the low coherence light are used, and the optical path length of one of the measurement light and the reference light is adjusted according to the position of the optical surface to be measured among the plurality of optical surfaces of the lens. Therefore, the measurement light reflected on the optical surface having the same center of curvature position as the optical surface to be measured or the optical surface having a narrow air distance from the optical surface to be measured should not interfere with the reference light. This makes it possible to detect the combined light of the measurement light reflected on the optical surface to be measured and the reference light from the combined light of the measurement light reflected on the optical surface of the lens and the reference light.

In the eccentricity measuring method according to still another aspect of the present invention, the low coherence light emitted from the low coherence light source is demultiplexed into the measurement light and the reference light, and the measurement light and the reference light are used to obtain the lens. This is an eccentricity measuring method for measuring the amount of eccentricity at the center of curvature of the optical surface to be measured with respect to the design center of curvature of the optical surface to be measured among a plurality of optical surfaces. The optical path length of one of the measurement light and the reference light before being combined by the combining portion is set as the step of generating the combined wave light by combining the measurement light and the reference light reflected by the optical surface to be measured. A step of adjusting by the optical path length adjusting unit according to the position of, a step of phase-modulating one of the measurement light and the reference light before being combined by the optics unit by the phase modulation unit, and the measurement light by the objective lens. Is a step of concentrating the light on the scanning surface where the design curvature center position of the optical surface to be measured exists and irradiating the optical surface of the lens. The step of irradiating the optical surface of the lens with the measurement light while moving it above, the step of acquiring the detection output corresponding to the combined wave light generated by the combined wave unit by the detection unit, and the detection output acquired by the detection unit. This includes a step in which the measuring unit measures the amount of eccentricity of the center of curvature position of the optical surface to be measured with respect to the design center position of curvature based on the scanning information by the scanning unit.

According to the present invention, it is possible to accurately measure the amount of eccentricity of the actual curvature center position with respect to the design curvature center position of the optical surface to be measured of the lens.

FIG. 1 is a configuration diagram showing a main component of a first embodiment of the eccentricity measuring device according to the present invention. FIG. 2 is a block diagram showing a configuration example of the optical path length adjusting unit 35. FIG. 3 is a block diagram of a main part including a control unit of the eccentricity measuring device 1 shown in FIG. FIG. 4 is a graph used to explain the operation of the balance detector 37. FIG. 5 is another graph used to explain the operation of the balance detector 37. FIG. 6 is yet another graph used to illustrate the operation of the balance detector 37. FIG. 7 is a diagram showing the axial tilt and the axial deviation of the lens. FIG. 8 is a configuration diagram showing a main component of a second embodiment of the eccentricity measuring device according to the present invention. FIG. 9 is a graph showing the signal strength output from the image sensor 140, which changes according to the scanning angle of the scanning mirror 44. FIG. 10 is a diagram showing an image showing a two-dimensional intensity distribution imaged by the image sensor 140. FIG. 11 is a configuration diagram showing a main component of a fourth embodiment of the eccentricity measuring device according to the present invention. FIG. 12 is a block diagram of a main part including a control unit of the eccentricity measuring device shown in FIG. FIG. 13 is a graph showing an example of the detection output (light intensity) of the photodetector that changes according to the scanning angle of the scanning mirror. 14 (A) and 14 (B) are graphs showing other examples of the detection output (light intensity) of the photodetector, which changes according to the scanning angle of the scanning mirror, respectively. FIG. 15 is a configuration diagram showing a modified example of the fourth embodiment of the eccentricity measuring device according to the present invention. FIG. 16 is a configuration diagram showing a main component of a fifth embodiment of the eccentricity measuring device according to the present invention. FIG. 17 is a diagram showing an eccentricity measuring device of a comparative example with the eccentricity measuring device of the fifth embodiment shown in FIG. FIG. 18 is a configuration diagram showing a main component of a sixth embodiment of the eccentricity measuring device according to the present invention. FIG. 19 is a flowchart showing a first embodiment of the eccentricity measuring method according to the present invention. FIG. 20 is a flowchart showing a second embodiment of the eccentricity measuring method according to the present invention. FIG. 21 is a flowchart showing a third embodiment of the eccentricity measuring method according to the present invention.

Hereinafter, preferred embodiments of the eccentricity measuring apparatus and method according to the present invention will be described with reference to the accompanying drawings.

<First Embodiment of Eccentricity Measuring Device>
FIG. 1 is a configuration diagram showing a main component of a first embodiment of the eccentricity measuring device according to the present invention.

The eccentricity measuring device 1 shown in FIG. 1 is a device for measuring the amount of eccentricity of the actual center of curvature position with respect to the design center of curvature of the optical surface to be measured of the set lens 10, and mainly includes a low coherence light source 20 and a low coherence light source 20. It is configured to include an interferometer 30 and a measurement optical system 40.

The group lens 10 is configured as a group lens in which a plurality of lenses are incorporated in the lens barrel 12. In the set lens 10 of this example, three lenses 14, 16 and 18 are arranged in order from the objective side, but the number of set lenses 10 is not limited to three in this example and exceeds three. May be good. Further, the number of optical surfaces that can be the optical surfaces to be measured of the set lens 10 is twice the number of lenses. Further, the lens to be measured may be one lens incorporated in the lens barrel or a single lens before being incorporated in the lens barrel.

It is assumed that the assembled lens 10 is accurately positioned and fixed at the measurement position of the eccentricity measuring device 1 by a jig (not shown).

The low coherence light source 20 emits low coherence light having low coherence property, and for example, a superluminescent diode (SLD), a light emitting diode (LED), or the like can be applied.

The interferometer 30 is composed of a first coupler 31, a second coupler 32, a first circulator 33, a second circulator 34, an optical path length adjusting unit 35, a phase modulation unit 36, and a balance detector 37. Each part is connected by an optical fiber.

In the first coupler 31, the low coherence light L emitted from the low coherence light source 20 is incident through an optical fiber, and the low coherence light L is demultiplexed into the measurement light ML1 and the reference light RL1. It functions as a demultiplexer). The measurement light ML1 and the reference light RL1 demultiplexed by the first coupler 31 are guided to the first circulator 33 and the second circulator 34, respectively, via an optical fiber.

The first circulator 33 guides the measurement light ML1 to the measurement optical system 40 via the optical fiber FB1, and the return light of the measurement light ML1 from the measurement optical system 40 (reflection which is the measurement light reflected by the optical surface to be measured). The measurement light ML2, which is the measurement light), is guided to the second coupler 32.

The second circulator 34 guides the optical path length adjusting unit 35 via the optical path length adjusting fiber FB2, and guides the reference light RL2, which is the return light from the optical path length adjusting unit 35, to the phase modulation unit 36.

In the optical path length adjusting fiber FB2, for example, an optical fiber is wound around a columnar piezo element, and the piezo element is expanded or contracted in the radial direction to change the optical path length of the optical fiber.

The optical path length adjusting unit 35 also adjusts the optical path length of the reference light RL1. For example, as shown in FIG. 2, it is parallel to the collimator lens 35a that makes the reference light RL1 emitted from the optical path length adjusting fiber FB2 parallel light. It can be composed of an optical path length adjusting mirror 35b that reflects the reference light RL1 made into light, and a mirror driving unit 35c that moves the optical path length adjusting mirror 35b. The optical path length adjusting unit 35 can adjust the optical path length of the reference light RL1 by adjusting the position of the optical path length adjusting mirror 35b by the mirror driving unit 35c. The optical path length adjusting unit 35 can be used for coarse adjustment of the optical path length of the reference light RL1, and the optical path length adjusting fiber FB2 can be used for fine adjustment of the optical path length of the reference light RL1.

The optical path length adjusting unit is not limited to the one using the optical path length adjusting fiber FB2 and the optical path length adjusting unit 35, and various known ones can be applied.

Further, instead of adjusting the optical path length of the reference light by the optical path length adjusting unit 35, for example, the moving stage is moved according to the position of the optical path to be measured of the assembled lens 10, whereby the optical surface to be measured of the assembled lens 10 is moved. The optical path length of the measurement light reflected and returned by the above may be matched with the optical path length of the reference light.

The phase modulation unit 36 incidents the reference light RL2 whose optical path length has been adjusted by the optical path length adjusting fiber FB2 and the optical path length adjusting unit 35 from the second circulator 34, modulates the phase of the incident reference light RL2, and performs phase modulation. The referenced optical RL3 is guided to the second coupler 32. As the phase modulator 36, an EO modulator (EO: Electro-Optic) or an acousto-optic modulator (AOM: Acousto-Optic Mudulator ) can be used. Further, the phase of the reference light RL2 can be modulated by periodically expanding and contracting the cylindrical piezo element around which the optical path length adjusting fiber FB2 is wound in the radial direction. It is assumed that the phase modulation unit 36 of this example operates at 100 MHz, for example.

The second coupler 32 functions as a combiner that combines the measurement light ML2 and the reference light RL3 on the coaxial optical path, and outputs the combined light CL1 and CL2 having different phases.

The balance detector 37, which functions as a detection unit, photoelectrically converts the input combined wave light CL1 and CL2, differentially detects the photoelectrically converted electric signal, and detects the interference signal based on the differentially detected signal (interference signal). Outputs a detection signal that is intensity information corresponding to the intensity (amplitude).

Here, the intensity information includes the combined wave signal (interference signal) of the reflected light and the reference light of the present embodiment, the light amount distribution (intensity distribution) of the combined wave signal of the reflected light and the reference light, which will be described later, and the reflected light. It means the amount of light (≈ illuminance). The details of the operation of the balance detector 37 will be described later.

The detection unit may acquire a signal having the same frequency as the phase modulation frequency from the output of a light intensity detector such as a photodiode.

The measurement optical system 40 mainly includes a collimator lens 42, a scanning mirror 44, and an objective lens (first optical system) 46.

The collimator lens 42 makes the measurement light ML1 emitted from the end surface of the end portion FB1a of the optical fiber FB1 parallel light, and causes the measurement light ML1 to enter the scanning mirror 44.

The scanning mirror 44 is a member that constitutes the scanning portion 50 shown in FIG. 3, and functions as a bending portion that bends the optical path of the measurement light ML1. The bent portion includes a prism and the like in addition to the scanning mirror 44 which is an optical mirror.

The scanning mirror 44 reflects the incident parallel measurement light ML1 and causes it to enter the objective lens 46, and the bending angle (scanning angle) of the optical path of the measurement light ML1 is controlled by the mirror control unit 52 that functions as a scanning control unit. As a result, the angle of incidence of the measurement light ML1 on the objective lens 46 is changed. As the scanning mirror 44, for example, an electromagnetically driven MEMS (Micro-Electro-Mechanical Systems) mirror can be applied.

The objective lens 46 focuses the measurement light ML1 on the scanning surface 48 on which the design curvature center position of the optical surface to be measured exists among the plurality of optical surfaces of the set lens 10, and is the optical surface to be measured. The position of the objective lens 46 in the optical axis direction is adjusted according to the design center position of curvature. In the example shown in FIG. 1, the position of the objective lens 46 (scanning surface 48 for condensing the measurement light ML1) is set with the optical surface on the image plane side of the lens 16 as the optical surface to be measured.

The optical axis of the measurement optical system 40 coincides with the reference axis of the positioned group lens 10 (the central axis of the lens barrel 12 and the design optical axis of the group lens 10). For example, the scanning angle of the scanning mirror 44 at which the eccentricity measurement position measured when a reference lens (prototype or the like) with zero eccentricity is set on the stage is the eccentricity zero position is set to zero degree. In this case, the definition of the eccentric amount to be measured is the vector amount of the center of curvature of the optical surface to be measured with respect to the assembly reference axis.

Further, a reference lens having zero eccentricity is set on the stage, and the bending angle information of the scanning mirror 44 corresponding to the measurement position of the eccentricity measured with respect to the reference lens is stored as the reference bending angle information in a storage unit (not shown). .. The information obtained by subtracting the reference bending angle information stored in the storage unit from the arbitrary bending angle information of the scanning mirror 44 becomes the information corresponding to the amount of eccentricity of the curvature center position of the optical surface to be measured with respect to the assembly reference axis.

Further, a lens having eccentricity may be used as a reference lens (prototype, etc.). In this case, if the reference lens is placed on a rotation stage and the rotation center position when rotated is set to the eccentricity zero position. Good.

By tilting the scanning mirror 44, the position where the measurement light ML1 is focused by the objective lens 46 can be moved on the scanning surface 48.

The measurement light ML1 irradiated to the assembled lens 10 via the objective lens 46 is reflected by each optical surface including the optical surface to be measured of the assembled lens 10. The measurement light ML2, which is the reflected light (return light) of the measurement light ML1 from each optical surface including the optical surface to be measured of the set lens 10, is again optical fiber via the objective lens 46, the scanning mirror 44, and the collimator lens 42. It is incident on the end face of the end portion FB1a of the FB1.

Further, between the collimator lens 42 of the measurement optical system 40 and the end portion FB1a of the optical fiber FB1, a half mirror 41 that reflects a part of the measurement light ML2 that is the return light and transmits the rest, and a half mirror 41. An image sensor 43 on which a part of the measurement light ML2 reflected by the above is incident is provided.

Here, when the position where the measurement light ML1 is focused by the objective lens 46 is accurately set according to the position of the center of curvature of the optical surface to be measured of the set lens 10, the measurement is the return light from each optical surface. The reflected light from the optical surface to be measured contained in the light ML2 is imaged as a point image on the image sensor 43, and the reflected light from the other optical surface is imaged as a blurred image.

Therefore, the position of the objective lens 46 can be finely adjusted based on the image acquired by the image sensor 43. When an optical surface having the same center of curvature position as the optical surface to be measured exists in the assembled lens 10, a plurality of point images are formed on the image sensor 43.

FIG. 3 is a block diagram of a main part including a control unit of the eccentricity measuring device 1 shown in FIG.

As shown in FIG. 3, the eccentricity measuring device 1 has a scanning unit 50 having a scanning mirror 44 in addition to the optical path length adjusting unit 35 including the optical path length adjusting fiber FB2, the phase modulator 36, and the balance detector 37 described above. A control unit 60 including a measurement unit 62, a memory 64, and an objective lens control unit 70 are provided.

The scanning unit 50 includes a scanning mirror 44, a mirror control unit 52, and a tilt angle sensor 54. The mirror control unit 52 tilts the scanning mirror 44 according to a scanning command from the control unit 60, whereby the position where the measurement light ML1 is focused by the objective lens 46 is moved on the scanning surface 48.

The tilt angle sensor 54 detects an angle in the axial direction of each of the two orthogonal axes at the center of the scanning mirror 44 (position on the optical axis of the objective lens 46), and an optical runout angle (scanning) corresponding to the detected angle. The scanning angle signal indicating the angle) is output to the measuring unit 62. When the drive signal output from the mirror control unit 52 to the scanning mirror 44 (the driving unit of the scanning mirror 44) is proportional to the tilt angle of the scanning mirror 44, the measuring unit 62 is output from the mirror control unit 52. The scanning angle signal can be acquired based on the drive signal, and in this case, the tilt angle sensor 54 is unnecessary.

The control unit 60 is composed of a CPU (Central Processing Unit) and the like, and controls the optical path length adjusting unit 35, the phase modulation unit 36, the scanning unit 50, the objective lens control unit 70, and the display 80 in an integrated manner, and also controls the control unit 60. The measuring unit 62 included in is actually based on the detection signal input from the balance detector 37 and the scanning angle signal (scanning information) input from the tilt angle sensor 54 with respect to the design curvature center position of the optical surface to be measured. Measure the amount of eccentricity at the center of curvature of the optical surface to be measured.

The memory 64 includes a ROM (Read Only Memory), a flash ROM, and the like. The ROM or flash ROM contains an eccentricity measurement program executed by the control unit 60, various parameters or tables required for the eccentricity measurement, for example, information on the optical surface of the set lens 10 (number of optical surfaces, surface position, curvature). Information such as the center position), a table showing the relationship between the scanning angle and the amount of eccentricity, a relational expression, etc. are stored.

Now, as shown in FIG. 1, the optical surface of the lens 16 of the set lens 10 on the image plane side is the surface S2 with respect to the design curvature center position of the optical surface to be measured (hereinafter, simply referred to as “plane S2”). When measuring the amount of eccentricity at the actual center position of curvature, the control unit 60 controls the optical path length adjusting unit 35 based on the information on the surface position of the surface S2, and the measurement light ML1 from the first coupler is assembled. The optical path length until the light is reflected by the surface S2 of the lens 10 and is incident on the second coupler 32 as the measurement light ML2, and the reference light RL1 from the first coupler are referred to by the optical path length adjusting unit 35 and the reference light RL2. To match the optical path length until it enters the second coupler 32. As a result, the measurement light ML2 of the low coherence light and the measurement light ML2 reflected by the surface S2 and the reference light RL2 can interfere with each other.

Since low coherence light is used, even if the surface position of the surface S2 of the set lens 10 has an error with respect to the design surface position, the measurement light ML2 and the reference light RL2 reflected by the surface S2 are light. Although it is possible to interfere, the measurement light ML2 reflected by the optical surface other than the surface S2 and the reference light RL2 do not interfere with each other. Therefore, the low coherence light is preferably one having a coherence length that satisfies the above conditions.

The control unit 60 controls the position of the objective lens 46 in the optical axis direction through the objective lens control unit 70, and condenses the measurement light ML1 on the scanning surface 48 where the design center of curvature position of the surface S2 exists.

Further, the control unit 60 operates the phase modulation unit 36 at 100 MHz, for example, and the interference light of the combined light CL1 and CL2 in the second coupler 32 becomes the interference light that is modulated according to the modulation frequency. To do so.

Subsequently, the control unit 60 tilts the scanning mirror 44 through the mirror control unit 52, and moves the position where the measurement light ML1 is focused by the objective lens 46 on the scanning surface 48. The measuring unit 62 acquires the detection signal output from the balance detector 37 and the scanning angle signal output from the tilt angle sensor 54 during the scanning operation due to the tilt of the scanning mirror 44, and these detection signals and the scanning angle signal Based on the above, the amount of eccentricity of the actual center of curvature of the optical surface to be measured with respect to the design center of curvature of the optical surface to be measured is measured.

Next, based on the detection signal output from the balance detector 37 and the scanning angle signal output from the tilt angle sensor 54, the actual curvature of the optical surface to be measured with respect to the design curvature center position of the optical surface to be measured. A method of measuring the amount of eccentricity at the center position will be described.

4 to 6 are graphs used to explain the operation of the balance detector 37, respectively.

Now, it is assumed that there is another optical surface (hereinafter, simply referred to as "plane S1") having a center of curvature position on the scanning surface 48 of the surface S2 of the set lens 10. That is, it is assumed that the set lens 10 has surfaces S1 and S2 having the same design center position of curvature.

In this case, the signal intensity of the combined wave light CL1 or CL2 output from the second coupler 32 varies depending on the scanning angle of the scanning mirror 44 as shown in FIG. Note that, in FIGS. 4 to 6, for the sake of simplicity, the scanning mirror 44 shows a case where only the scanning angle (θ) of one axis changes.

In FIG. 4, when the scanning angle is θ1, the measurement light ML1 is focused on the center of curvature of the surface S1, the reflected light from the surface S1 is incident on the end surface of the end portion FB1a of the optical fiber FB1, and the scanning angle is θ2. At this time, the case where the measurement light ML1 is focused on the position of the center of curvature of the surface S2 and the reflected light from the surface S2 is incident on the end surface of the end portion FB1a of the optical fiber FB1 is shown.

In this case, the signal intensity of the combined light CL1 or CL2 at the scanning angle θ1 is increased because the reflected light from the surface S1 is collected and incident on the end surface of the end portion FB1a of the optical fiber FB1, but is reflected by the surface S1. Since the measurement light ML2 and the reference light RL2 have different optical path lengths (different beyond the coherence length of the low coherence light), they are non-interfering signals corresponding to the non-interfering combined light.

On the other hand, the signal intensity of the combined light CL1 or CL2 at the scanning angle θ2 is increased because the reflected light from the surface S2 is collected and incident on the end surface of the end portion FB1a of the optical fiber FB1, and is reflected by the surface S2. Since the measurement light ML2 and the reference light RL2 are adjusted so that the optical path lengths are the same, they are interference signals corresponding to the interfering combined light, and since the reference light RL2 is phase-modulated, the modulation frequency. The amplitude changes according to.

The balance detector 37 photoelectrically converts the combined wave light CL1 and CL2, respectively, and differentially detects the photoelectrically converted electric signal. As shown in FIG. 5, the differentially detected signal is only an interference signal from which noise such as a non-interference signal (signal component corresponding to the reflected light from the surface S1) has been removed. The amplitude of this interference signal changes due to phase modulation.

The balance detector 37 synchronously detects an interference signal whose amplitude changes due to phase modulation at the same frequency as the modulation frequency (100 MHz) of the phase modulation unit 36, and outputs a detection signal corresponding to the intensity (amplitude) of the interference signal. .. In the example shown in FIG. 6, the detection signal is maximized when the scanning angle is θ2.

When the detection signal output from the balance detector 37 has the maximum scanning angle, the measurement light ML1 is focused on the actual center position of curvature of the surface S2, so that the measurement unit 62 performs the balance detection. The actual center of curvature position of the surface S2 is obtained based on the scanning angle at which the detection signal input from the device 37 is maximized, and the amount of eccentricity of the actual center of curvature position with respect to the design center of curvature position of the surface S2 is measured. Can be done. Since the scanning angle of the scanning mirror 44 and the condensing position of the measurement light ML1 on the scanning surface 48 have a one-to-one correspondence, the condensing of the measurement light ML1 on the scanning surface 48 is based on the scanning angle of the scanning mirror 44. The position (the actual center position of curvature of the optical surface to be measured) can be obtained, and thereby the amount of eccentricity of the actual center position of curvature with respect to the design center position of the optical surface to be measured can be measured.

The amount of eccentricity of the optical surface to be measured of the assembled lens measured by the measuring unit 62 is displayed on the display 80 in association with the surface number indicating the optical surface to be measured of the assembled lens, or the flash ROM of the memory 64 or the like. Can be saved in.

Further, by measuring the amount of eccentricity of the optical surface to be measured of the assembled lens 10, it is possible to obtain the axial tilt and the axial deviation of the lens incorporated in the lens barrel 12.

Now, as shown in FIG. 7, the design center positions of curvature of the optical surfaces 16a and 16b of the lens 16 are set to O1 and O2, respectively, and the measured actual center positions of curvature of the optical surfaces 16a and 16b are P1 and P2, respectively. Then, the straight line passing through the curvature center positions O ₁ and O ₂ is the reference axis Lo (design optical axis) of the set lens 10 in which the lens 16 is incorporated, and passes through the curvature center positions P ₁ and P ₂ . The straight line is the optical axis Lp of the lens 16.

In this case, the angle α formed by the reference axis Lo and the optical axis Lp indicates the axial tilt of the lens 16, and the deviation amount δ between the reference axis Lo and the center position of the lens 16 indicates the axial deviation of the lens 16.

In the eccentricity measuring device 1 of the first embodiment shown in FIG. 1, the optical path length of the reference light is adjusted by the optical path length adjusting unit 35, but the optical path length of the measurement light is not limited to this. You may try to adjust. Similarly, the phase modulation unit 36 modulates the phase of the reference light, but the present invention is not limited to this, and the phase of the measurement light may be modulated. Further, the detector that detects the amplitude information of the phase-modulated interference signal contained in the combined wave light is not limited to the balance detector 37, but an envelope detector and other known detectors can be applied, which is necessary. Can be any as long as it outputs a detection signal indicating the strength of the phase-modulated interference signal.

<Second Embodiment of Eccentricity Measuring Device>
FIG. 8 is a configuration diagram showing a main component of a second embodiment of the eccentricity measuring device according to the present invention. In FIG. 8, the same reference numerals are given to the parts common to the eccentricity measuring device 1 of the first embodiment shown in FIG. 1, and detailed description thereof will be omitted.

In the eccentricity measuring device 2 of the second embodiment shown in FIG. 8, the interferometer 100 is mainly different from the interferometer 30 of the first embodiment.

The interferometer 100 mainly includes a first collimator lens 110, a beam splitter 120, a reflection mirror 130, and an image sensor 140.

The first collimator lens 110 converts the low coherence light emitted from the low coherence light source into parallel light and causes it to be incident on the beam splitter 120.

The beam splitter 120 functions as a demultiplexing unit that divides the incident low coherence light into the measurement light and the reference light, and reflects a part of the incident low coherence light as the measurement light to the measurement optical system 40-2. It is incident, and the rest is transmitted as reference light and incident on the reflection mirror 130.

Further, the beam splitter 120 functions as a combiner for merging the measurement light which is the return light from the measurement optical system 40-2 and the reference light which is the reflected light from the reflection mirror 130, and the measurement optical system 40- The measurement light from 2 is transmitted and incident on the image sensor 140, and the reference light from the reflection mirror 130 is reflected and incident on the image sensor 140.

The reflection mirror 130 functions as an optical path length adjusting mirror whose mirror position is adjusted by a mirror driving unit (not shown). By adjusting the position of the reflection mirror 130, the optical path length of the measurement light reflected and returned by the optical surface to be measured of the set lens 10 and the light path length reflected by the reflection mirror 130 at the position where the beam splitter 120 combines the waves. It can be matched with the optical path length of the returning reference light.

Further, the reflection mirror 130 functions as a part of a phase modulation unit that phase-modulates the reference light by vibrating at high speed (for example, 100 MHz) by a piezo element or the like.

The measurement optical system 40-2 is different from the measurement optical system 40 shown in FIG. 1 in that a condenser lens 45 and a spatial filter 47 are added.

The condensing lens 45 condenses the measurement light of the parallel light demultiplexed by the beam splitter 120. The spatial filter 47 is provided at a position where the measurement light is focused by the condenser lens 45 (the focal position of the condenser lens 45), and has a pinhole through which the collected measurement light passes. The measurement light collected by the condenser lens 45 is converted into parallel light again by the collimator lens 42 (second collimator lens).

The measurement light incident from the interferometer 100 passes through the pinhole of the space filter 47, and a part of the return light of the measurement light reflected by the optical surface of the set lens 10 and returned is the pinhole of the space filter 47. And enter the interferometer 100. Therefore, the pinhole of the spatial filter 47 corresponds to the end face of the end portion FB1a of the optical fiber FB1 in the measurement optical system 40 shown in FIG.

The image sensor 140 that functions as a detection unit is incident with the combined light of the measurement light and the reference light combined by the beam splitter 120, and the image sensor 140 outputs a detection signal according to the intensity of the incident combined light. To do.

FIG. 9 is a graph showing the signal strength output from the image sensor 140, which changes according to the scanning angle of the scanning mirror 44. In FIG. 9, for the sake of simplicity, the scanning mirror 44 shows a case where only the scanning angle (θ) of one axis changes.

Here, the position of the reflection mirror 130 that functions as the optical path length adjusting mirror is aligned with the optical surface (plane S2) on the imaging surface side of the lens 16 of the set lens 10, and the objective lens 46 is designed with the surface S2. It is assumed that the measurement light is adjusted so as to be focused on the scanning surface 48 having the upper position of the center of curvature. Further, it is assumed that there is another optical surface (plane S1) having a center of curvature position on the scanning surface 48 of the surface S2 of the assembled lens 10.

As shown in FIG. 9, when the scanning angle θ1 that the measurement light is focused on the curvature center position of the surface S1, the signal intensity obtained from the image sensor 140 has a peak value, and similarly, the measurement light has the curvature center of the surface S2. When the scanning angle θ2 is focused on the position, the signal strength obtained from the image sensor 140 has a peak value.

The signal intensity of the combined light at the scanning angle θ1 is large because the reflected light from the surface S1 is collected and passes through the pinhole of the spatial filter 47, but the measurement light and the reference light reflected by the surface S1 are optical paths. Since the lengths are different, the combined light at the scanning angle θ1 does not interfere with the measurement light and the reference light. That is, the signal detected by the image sensor 140 at the scanning angle θ1 is a non-interfering signal.

On the other hand, the signal intensity of the combined light at the scanning angle θ2 is increased because the reflected light from the surface S2 is collected and passes through the pinhole of the space filter 47, and the measurement light and the reference light reflected by the surface S2. Is adjusted so that the optical path lengths are the same. Therefore, in the combined light at the scanning angle θ2, the measurement light and the reference light interfere with each other. That is, the signal detected by the image sensor 140 when the scanning angle is θ2 is an interference signal. Further, since the reference light is phase-modulated, it becomes an interference signal whose amplitude changes according to the modulation frequency.

Therefore, in the eccentricity measuring device 2 of the set lens of the second embodiment, when the signal obtained from the image sensor 140 becomes an interference signal whose amplitude changes according to the modulation frequency and the amplitude of the interference signal becomes maximum. By detecting the scanning angle of the scanning mirror 44 of the above, it is possible to measure the amount of eccentricity of the actual curvature center position with respect to the design curvature center position of the optical surface to be measured.

In the second embodiment, the image sensor 140 is used as a part of the detection unit, but another photoelectric detector such as a photodiode may be used. In this case, the image sensor 140 is parallel to the condenser lens. It is preferable that the combined wave light is focused on the light receiving portion of the photoelectric detector.

<Third Embodiment of the eccentricity measuring device of the assembled lens>
A third embodiment of the set lens eccentricity measuring device according to the present invention is, for example, a condenser lens 45 or a collimator lens 42 of the measurement optical system 40-2 of the set lens eccentricity measuring device 2 shown in FIG. It can be applied when there is spherical aberration in the lens.

When the amount of eccentricity of the optical surface (plane S2) of the lens 16 of the assembled lens 10 on the imaging surface side is measured by the eccentricity measuring device of the assembled lens of the third embodiment, the reflection mirror functions as an optical path length adjusting mirror. The position of the objective lens 46 so that the position (Z) of 130 is aligned with the position (Z0) corresponding to the surface S2 and the measurement light is focused on the scanning surface 48 having the design curvature center position of the surface S2. To adjust. As in the second embodiment, the assembled lens 10 has another optical surface (plane S1) having a center of curvature position on the scanning surface 48 of the surface S2.

The image sensor 140, which functions as an imaging unit, images the combined wave light combined by the beam splitter 120. The combined wave light captured by the image sensor 140 is captured as an image showing a two-dimensional intensity distribution as shown in FIG.

As shown in FIG. 10, when the measurement light has a scanning angle θ1 focused on the center of curvature of the surface S1, the image obtained from the image sensor 140 is captured as a circular image having substantially constant brightness. This is because the combined light at the scanning angle θ1 has different optical path lengths between the measurement light reflected on the surface S1 and the reference light, and the measurement light and the reference light do not interfere with each other.

In this case, even if the position Z of the reflection mirror 130 is moved from the position Z0 corresponding to the surface S2 by half a wavelength (λ / 2) of the low coherence light, the image obtained from the image sensor 140 hardly changes. This is because the non-interfering state does not change when the low coherence light moves by about half a wavelength (λ / 2).

On the other hand, when the scanning angle θ2 is such that the measurement light is focused on the position of the center of curvature of the surface S2, the image obtained from the image sensor 140 is captured as an interference fringe image as shown in FIG. This is because the combined light at the scanning angle θ2 has the same optical path length between the measurement light reflected on the surface S2 and the reference light, so that the measurement light and the reference light interfere with each other. Further, a two-dimensional intensity distribution of the combined wave light is generated by the spherical aberration of the lens (condensing lens 45 or collimator lens 42) constituting the measurement optical system 40-2, resulting in an interference fringe image.

In this case, if the position Z of the reflection mirror 130 is moved from the position Z0 corresponding to the surface S2 by half a wavelength (λ / 2) of the low coherence light, the shading of the interference fringe image is inverted.

The eccentricity measuring device of the set lens of the third embodiment image-analyzes an image showing the two-dimensional intensity distribution of the combined wave light obtained from the image sensor 140, images an interference fringe image, and contrasts the interference fringe image ( By detecting the scanning angle of the scanning mirror 44 when the sharpness) is maximized, it is possible to measure the amount of eccentricity of the actual curvature center position with respect to the design curvature center position of the optical surface to be measured.

Further, since the eccentricity measuring device of the set lens of the third embodiment uses an image showing the two-dimensional intensity distribution of the combined wave light (because the interference signal corresponding to the phase modulation is not used), the reflection mirror 130 is vibrated. It differs from the eccentricity measuring device 2 of the set lens of the second embodiment in that a phase modulation unit for phase-modulating the reference light is not required.

The eccentricity measuring device for the set lens of the third embodiment is not limited to the case where the lens constituting the measurement optical system 40-2 has spherical aberration, and the reflective surface of the reflective mirror 130 is provided with slight irregularities. Therefore, interference fringes may be generated, or when the optical surface to be measured of the set lens 10 is an aspherical surface, interference fringes can be generated by the aspherical surface.

<Fourth Embodiment of Eccentricity Measuring Device>
FIG. 11 is a configuration diagram showing a main component of a fourth embodiment of the eccentricity measuring device for a set lens according to the present invention. In FIG. 11, the same reference numerals are given to the parts common to the eccentricity measuring device 2 of the set lens of the second embodiment shown in FIG. 8, and detailed description thereof will be omitted.

The eccentricity measuring device 4 for the set lens of the fourth embodiment shown in FIG. 11 mainly replaces the interferometer 100 of the second embodiment with the light source 22, the collimator lens 110 which is a part of the measurement optical system, and the beam. A splitter (first demultiplexing unit) 124, a condenser lens (first condenser lens) 126, and a photodetector 142 that functions as a detection unit are provided.

Light source 22, LED that emits low coherence light, other lamps (halogen lamps, xenon lamps, etc.), including a laser light source for emitting a laser beam is coherent light.

The measurement light emitted from the light source 22 is collimated by the first collimator lens 110 and incident on the beam splitter 124. A part of the measurement light incident on the beam splitter 124 is reflected here and guided as the measurement light to the condenser lens (second condenser lens) 45 of the measurement optical system 40-2.

On the other hand, a part of the return light (reflection measurement light) of the measurement light reflected and returned by the optical surface of the set lens 10 passes through the pinhole of the space filter 47, and the beam passes through the condenser lens 45. It is incident on the splitter 124. A part of the return light incident on the beam splitter 124 passes through the beam splitter 124 and is guided to the condenser lens 126.

The condenser lens 126 collects the return light of the measurement light reflected by the optical surface of the set lens 10 and causes it to enter the photodetector 142.

The photodetector 142 is composed of a photoelectric conversion element such as a photodiode, and outputs an electric signal corresponding to the return light (detection light amount) incident on the condenser lens 126.

FIG. 12 is a block diagram of a main part including a control unit of the eccentricity measuring device 4 of the set lens shown in FIG. In FIG. 12, the same reference numerals are given to the parts common to the first embodiment shown in FIG. 3, and detailed description thereof will be omitted.

In FIG. 12, the mirror control unit 52 tilts the scanning mirror 44 in accordance with a scanning command from the control unit 60-2, whereby the focusing position at which the measurement light ML1 is focused by the objective lens 46 is set on the scanning surface 48. Move with.

The measuring unit 62-2 included in the control unit 60-2 shows the detection output corresponding to the detected light amount of the measured light from the photodetector 142 and the optical runout angle (scanning angle) of the scanning mirror 44 from the tilt angle sensor 54. A scanning angle signal is added, and the measuring unit 62-2 determines the design curvature center of the optical surface to be measured based on the detection output input from the photodetector 142 and the scanning angle signal input from the tilt angle sensor 54. The amount of eccentricity at the center of curvature of the actual optical surface to be measured with respect to the position is measured.

FIG. 13 is a graph showing an example of the detection output of the photodetector 142 (the amount of detected light incident on the photodetector 142) that changes according to the scanning angle of the scanning mirror 44. In FIG. 13, for the sake of simplicity, the scanning mirror 44 shows a case where only the scanning angle (θ) of one axis changes.

When the pinhole diameter of the spatial filter 47 (FIGS. 8 and 11 ) is “small” and the peak width of the detection output exceeding the threshold Th is equal to or less than the required measurement resolution as shown in FIG. 13, the measuring unit 62-2 determines whether or not the detection output of the photodetector 142 corresponds to the detection output exceeding the threshold Th. When the detection output of the photodetector 142 exceeds the threshold value Th, the measuring unit 62-2 determines that the detection output of the photodetector 142 has reached the peak value, and acquires the scanning angle signal input from the tilt angle sensor 54 at that time. ..

Then, the measuring unit 62-2 determines the actual center of curvature position of the optical surface to be measured (the actual center of curvature with respect to the design center of curvature of the optical surface to be measured) based on the acquired scanning angle signal (scanning angle). Eccentricity) is measured.

On the other hand, when the pinhole diameter of the spatial filter 47 is “medium” or “large”, the measurement resolution requires the peak width of the detection output exceeding the threshold Th as shown in FIGS. 14 (A) and 14 (B). If it exceeds, the measuring unit 62-2 searches for a scanning angle at which the detection output of the photodetector 142 becomes the maximum value. That is, the measuring unit 62-2 stores the relationship between the detection output of the photodetector 142 and the scanning angle in the memory, and compares the magnitudes of the respective detection outputs to search for the scanning angle at which the detection output becomes the maximum value.

When the detection output shown in FIG. 13 is obtained, the scanning angle at which the peak value is obtained can be detected at a higher speed than when the detection output shown in FIGS. 14A and 14B is obtained. Further, as the pinhole diameter of the spatial filter 47 becomes larger, the peak value detection error becomes larger, and as a result, the measurement error of the eccentric amount becomes larger.

When the light source 22 is a laser light source, the pinhole diameter of the spatial filter 47 can be easily reduced. Therefore, the light source 22 of the fourth embodiment is preferably a laser light source. The order of coupling efficiency to the spatial filter 47 is laser> LED> lamp.

<Modification example of the fourth embodiment of the eccentricity measuring device>
FIG. 15 is a configuration diagram showing a modified example of the fourth embodiment of the eccentricity measuring device according to the present invention. In FIG. 15, the same reference numerals are given to the parts common to the eccentricity measuring device 1 of the first embodiment shown in FIG. 1 and the eccentricity measuring device 4 of the fourth embodiment shown in FIG. However, the detailed description thereof will be omitted.

The eccentricity measuring device 4-1 of the modified example of the fourth embodiment shown in FIG. 15 is provided with a light source 22, a circulator 125, and a photodetector 142 mainly in place of the interferometer 30 of the first embodiment, and is provided with a light source. An optical fiber (first optical fiber) FB1 is arranged between 22 and the circulator 125, and an optical fiber (second optical fiber) FB2 is arranged between the circulator 125 and the collimator lens 42, and the circulator 125 is provided. An optical fiber (third optical fiber) FB3 is arranged between the photo detector 142 and the photo detector 142.

The measurement light from the light source 22 is emitted to the collimator lens 42 from the end face of the end portion FB2a of the optical fiber FB2 via the first optical fiber FB1, the circulator 125, and the optical fiber FB2, and is converted into parallel light by the collimator lens 42. , Is incident on the scanning mirror 44.

A part of the return light of the measurement light reflected by the optical surface of the assembled lens 10 and returned is incident on the end surface of the end portion FB2a of the optical fiber FB2, and passes through the optical fiber FB2, the circulator 125, and the optical fiber FB3. It is incident on the photodetector 142.

In the modified example of the fourth embodiment, the end surface of the end portion FB2a of the optical fiber FB2 corresponds to the pinhole of the spatial filter 47 of the fourth embodiment.

According to the modified example of the fourth embodiment, the eccentricity of the lens can be measured by the same method as that of the fourth embodiment, and since the optical fiber is used, the degree of freedom in the design of the optical system is increased. It can be an expensive and inexpensive device.

<Fifth Embodiment of the eccentricity measuring device>
FIG. 16 is a configuration diagram showing a main component of a fifth embodiment of the eccentricity measuring device according to the present invention. In FIG. 16, the same reference numerals are given to the parts common to the eccentricity measuring device 4 of the fourth embodiment shown in FIG. 11, and detailed description thereof will be omitted.

The measurement optical system of the eccentricity measuring device 5 of the fifth embodiment shown in FIG. 16 includes a beam splitter 124, a collimator lens 200, a scanning mirror 44, an adapter lens 210, and a varifocal lens 220 that functions as an objective lens. It is composed of and.

The collimator lens 200 makes the measurement light incident from the light source 22 through the beam splitter 124 into parallel light and causes it to enter the scanning mirror 44.

The measurement light reflected by the scanning mirror 44 enters the varifocal lens (first lens) 220 via the adapter lens 210.

Here, the variable focus lens 220 includes a varifocal lens and a liquid lens. A liquid lens is a lens with a variable focus that can change the shape of the enclosed liquid by electrical control (voltage) and change the focal length of the lens itself. The adapter lens (second optical system) 210 is a lens that changes the maximum and minimum values of the refractive power of the measurement optical system that combines the adapter lens 210 and the varifocal lens 220, and is the variable focal range of the varifocal lens 220. Has a function to adjust.

The focal length of the collimator lens 200 of this example is 100 mm, and the focal length of the adapter lens 210 is 50 mm.

The scanning angle required for measuring the axial tilt α (angle α shown in FIG. 7) of the lens having the assembled lens 10 may be α (the angle of the scanning mirror 44 is α / 2).

Further, in FIG. 16, L1 indicates the distance from the scanning mirror 44 to the variable focus lens 220, and WD is the distance from the variable focus lens 220 to the first optical surface (plane 1) of the assembled lens 10.

When the axis tilt α of the lens becomes large, a part of the measurement light does not fit within the diameter of the varifocal lens 220 and does not pass through the varifocal lens (a part of the measurement light does not pass through the measurement optical system). It is called the eclipse of the measurement light.) In the present embodiment, the vignetting of the measurement light in the varifocal lens 220 is determined by the distance L1, but according to the measurement optical system using the scanning mirror 44, the varifocal lens 220 is a small-diameter liquid lens (for example, φ16 mm). , Φ5.8 mm), it is possible to measure a long set lens.

The positions of the adapter lens 210 and the varifocal lens 220 of the measurement optical system of the eccentricity measuring device 5 of the assembled lens may be interchanged.

FIG. 17 is a diagram showing an eccentricity measuring device of a comparative example with the eccentricity measuring device 5 of the fifth embodiment shown in FIG. In FIG. 17, the same reference numerals are given to the parts common to the fifth embodiment of FIG. 16, and detailed description thereof will be omitted.

In FIG. 17, L2 is the distance from the varifocal lens 220 to the final optical surface of the assembled lens 10. In the measurement optical system shown in FIG. 17, the vignetting of the measurement light in the varifocal lens 220 is determined by the distance L2 and the optical axis tilt α of the lens. The reflection angle of the lens with respect to the optical axis tilt α is 2α.

Assuming that the distance L2 is 50 mm and the lens axis tilt α is 60 minutes, the optical axis of the reflected light from the last optical surface of the assembled lens 10 passes through the outer circumference of 1.7 mm at the position of the varifocal lens 220. As a result, vignetting portion V due to the reflection angle 2α is generated with respect to the axial tilt α of the lens, and it becomes impossible to measure a lens having a long overall length. In order to reduce vignetting, it is necessary to make the distance WD as small as possible.

According to the present embodiment shown in FIG. 16, because changing the incident angle of the measuring light by the scanning mirror 44, the center of curvature without being affected by vignetting of the measuring light in a wide range with respect to the comparative example shown in FIG. 1 7 It is possible to scan the position. Further, by using a lens such as a liquid lens that changes the focal distance of the lens itself as the variable focus lens 220, even if the focus of the variable focus lens 220 is changed, the measurement light is eclipsed depending on the angle of the scanning mirror 44. Does not change, which facilitates measurement. Further, for a lens such as a liquid lens that changes the focal length of the lens itself, the maximum and minimum values of the refractive power that can be changed by electrical control are limited. The variable focal length of the measurement optical system can be adjusted by combining the adapter lens 210 and a lens such as a liquid lens that changes the focal length of the lens itself. This makes it possible to improve the electrical adjustment accuracy of the focal length.

Further, in the fifth embodiment shown in FIG. 16, the measurement light emitted from the light source 22 and the measurement light reflected by the group lens 10 are split by the beam splitter 124, and the measurement light reflected by the group lens 10 is the light source. Although it is detected by the photodetector 142 installed on a plane different from that of 22, in FIG. 16, the beam splitter 124 may be removed and the photodetector 142 may be installed around the light source 22.

<Sixth Embodiment of Eccentricity Measuring Device>
FIG. 18 is a configuration diagram showing a main component of a sixth embodiment of the eccentricity measuring device according to the present invention. In FIG. 18, the same reference numerals are given to the parts common to the eccentricity measuring device 5 of the fifth embodiment shown in FIG. 16, and detailed description thereof will be omitted.

In the eccentricity measuring device 6 of the sixth embodiment shown in FIG. 18, the varifocal lens 220 and the adapter lens 210 are provided on the incident side of the scanning mirror 44, and the varifocal lens 220 and the adapter lens 210 are provided on the scanning mirror 44. This is different from the eccentricity measuring device 5 of the fifth embodiment provided on the exit side of the lens.

In the eccentricity measuring device 6 of the sixth embodiment shown in FIG. 18, a scanning mirror 44 is arranged between the variable focus lens 220 and the assembled lens 10, and the scanning mirror 44 and the assembled lens 10 are separated from each other. No optical member is provided.

According to the eccentricity measuring device 6 of the sixth embodiment, there is an advantage that the influence of vignetting of the measurement light in the varifocal lens 220 is eliminated depending on the angle of the scanning mirror 44.

In the eccentricity measuring device 5 of the fifth embodiment and the eccentricity measuring device 6 of the sixth embodiment, the eccentricity measuring device 1 to the eccentricity measuring device 4 of the fourth embodiment are described. Interference measurements using a low coherence light source may be combined. A low coherence light source is used as the light source 22, and the measurement light reflected by the group lens 10 and the measurement light are combined for interference measurement to separate which optical surface of the group lens 10 the reflected light is reflected. Can be done.

<First Embodiment of Eccentricity Measurement Method>
FIG. 19 is a flowchart showing a first embodiment of the eccentricity measuring method according to the present invention.

The control unit 60 shown in FIG. 3 executes the process shown in FIG. 19 according to the eccentricity measuring program stored in the memory 64.

In FIG. 19, the parameter i for specifying the optical surface to be measured of the set lens is set to 1 (step S10). Parameter i indicates the surface number of the optical surface to be measured of the set lens.

Subsequently, the optical path length of the reference light and the objective lens are adjusted according to the optical surface (Si) to be measured with the surface number of the parameter i (step S12). That is, the control unit 60 controls the optical path length adjusting unit 35, and adjusts the optical path length of the reference light so as to match the optical path length of the measurement light reflected by the surface Si and returned. Further, the control unit 60 controls the position of the objective lens 46 via the objective lens control unit 70, and collects the measurement light on the scanning surface having the design center of curvature position of the surface Si.

Subsequently, the control unit 60 controls the angle (scanning angle) of the scanning mirror 44 via the mirror control unit 52, and moves the condensing position of the measurement light on the scanning surface (step S14).

The measuring unit 62 acquires the detection output of the balance detector 37 for each scanning angle of the scanning mirror 44 (step S16), and determines whether or not the detected output acquired for each position on the scanning surface has reached the maximum value. (Step S18).

When it is determined that the detection output of the balance detector 37 is not the maximum value (in the case of "No"), the process returns to step S14, the scanning angle of the scanning mirror 44 is changed, and the processes of steps S14 to S18 are repeated. On the other hand, when it is determined that the detection output of the balance detector 37 is the maximum value (in the case of "Yes"), the process proceeds to step S20.

In step S20, the measuring unit 62 acquires the scanning angle of the scanning mirror 44 when the detection output of the balance detector 37 reaches the maximum value. Then, based on the acquired scanning angle of the scanning mirror 44, the amount of eccentricity of the actual curvature center position with respect to the design curvature center position of the surface Si is measured (step S22).

Next, it is determined whether or not the parameter i becomes N (step S24). N is the number of all optical surfaces of the set lens.

If the parameter i is not N (in the case of "No"), the parameter i is incremented by 1 (step S26), the transition to step S12 is performed, and steps S12 to S24 are repeatedly executed.

When the parameter i is N (when "Yes"), it is assumed that the measurement of the eccentricity amount of all the optical surfaces of the assembled lens is completed, and this process is terminated.

<Second Embodiment of Eccentricity Measurement Method>
FIG. 20 is a flowchart showing a second embodiment of the eccentricity measuring method according to the present invention. In FIG. 20, the steps common to the first embodiment of the eccentricity measuring method shown in FIG. 19 are assigned the same step numbers, and detailed description thereof will be omitted.

The eccentricity measuring method of the second embodiment is a method corresponding to the eccentricity measuring device 3 of the third embodiment described above.

The flowchart shown in FIG. 20 includes steps S30 to S36 instead of steps S16 to S20 of the flowchart shown in FIG.

In step S30, an image showing the two-dimensional intensity distribution of the combined wave light synthesized by the beam splitter 120 for each scanning angle of the scanning mirror 44 (for each focusing position of the measurement light on the scanning surface) functions as an imaging unit. An image is taken by the image sensor 140 to acquire an image showing a two-dimensional intensity distribution.

An image showing the acquired two-dimensional intensity distribution is analyzed (step S32). It is determined whether or not the image acquired based on the image analysis result becomes an interference fringe image and the contrast (sharpness) of the interference fringe image is maximized (step S34).

Then, when the acquired image becomes an interference fringe image and it is determined that the contrast of the interference fringe image is not the maximum (in the case of "No"), the process returns to step S14, the scanning angle of the scanning mirror 44 is changed, and step S14 The process of step S34 is repeated.

On the other hand, when the acquired image becomes an interference fringe image and it is determined that the contrast of the interference fringe image is the maximum (in the case of "Yes"), the transition to step S36 is performed.

In step S36, the scanning angle of the scanning mirror 44 when the contrast of the interference fringe image is maximized is acquired. Then, based on the acquired scanning angle of the scanning mirror 44, the amount of eccentricity of the actual curvature center position with respect to the design curvature center position of the surface Si is measured (step S22).

<Third embodiment of the eccentricity measuring method>
FIG. 21 is a flowchart showing a third embodiment of the eccentricity measuring method according to the present invention. In FIG. 21, the steps common to the first embodiment of the eccentricity measuring method shown in FIG. 19 are assigned the same step numbers, and detailed description thereof will be omitted.

The eccentricity measuring method of the third embodiment is a method corresponding to the eccentricity measuring device 4 of the fourth embodiment described above.

The flowchart shown in FIG. 21 includes steps S40 to S46 instead of steps S12 and S16 to S20 of the flowchart shown in FIG.

In step S40, the objective lens is adjusted according to the optical surface (Si) to be measured with the surface number of the parameter i. That is, the control unit 60-2 (FIG. 12) controls the position of the objective lens 46 via the objective lens control unit 70, and collects the measurement light on the scanning surface having the design curvature center position of the surface Si. Let me.

For each scanning angle of the scanning mirror 44, the photodetector 142 acquires the detection output corresponding to the return light from the surface Si incident through the spatial filter 47, the condenser lens 126, and the like (step S42).

Subsequently, the measuring unit 62-2 determines whether or not the detection output of the photodetector 142 exceeds the threshold value Th as shown in FIG. 13 (step S44). If the detection output does not exceed the threshold Th (in the case of “No”), the process returns to step S14, and the angle of the scanning mirror 44 is continuously controlled.

When the detection output exceeds the threshold value Th (in the case of “Yes”), the measuring unit 62-2 determines that the detection output by the photodetector 142 has reached the peak value, and transitions to step S46.

In step S46, the angle (scanning angle) of the scanning mirror 44 when the detection output of the photodetector 142 exceeds the threshold value Th is acquired from the tilt angle sensor 54. Then, based on the acquired scanning angle of the scanning mirror 44, the amount of eccentricity of the actual curvature center position with respect to the design curvature center position of the surface Si is measured (step S22).

In the above example, the angle at which the output of the balance detector takes the maximum value is acquired, but all the measurement data may be stored in the memory and the angle at which the output takes the maximum value may be extracted from all the measurement data. Further, in the above example, the optical surface is fixed and the angle of the scanning mirror is changed for measurement, but the angle of the scanning mirror may be fixed and the optical surface may be changed. Further, the optical surface may be fixed, the angle of the scanning mirror and the focal length of the varifocal lens may be changed, and the position of the center of curvature may be scanned in three dimensions.

[Other]
In the present embodiment, for example, the hardware structure of the processing unit that executes various processes of the control units 60 and 60-2 including the measurement units 62 and 62-2 has various hardware structures as shown below. Processor. For various processors, the circuit configuration can be changed after manufacturing the CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), etc., which are general-purpose processors that execute software (programs) and function as various processing units. Programmable Logic Device (PLD), a dedicated electric circuit, which is a processor having a circuit configuration specially designed to execute a specific process such as an ASIC (Application Specific Integrated Circuit). Is done.

One processing unit may be composed of one of these various processors, or may be composed of two or more processors of the same type or different types (for example, a plurality of FPGAs or a combination of a CPU and an FPGA). You may. Further, a plurality of processing units may be configured by one processor. As an example of configuring a plurality of processing units with one processor, first, one processor is configured by a combination of one or more CPUs and software, as represented by a computer such as a client or a server. There is a form in which the processor functions as a plurality of processing units. Secondly, as typified by System On Chip (SoC), there is a form in which a processor that realizes the functions of the entire system including a plurality of processing units with one IC (Integrated Circuit) chip is used. is there. As described above, the various processing units are configured by using one or more of the above-mentioned various processors as a hardware-like structure.

Further, the hardware structure of these various processors is, more specifically, an electric circuit (circuitry) in which circuit elements such as semiconductor elements are combined.

Further, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

1, 2 Eccentricity measuring device 10 sets Lens 12 Lens barrel 14, 16, 18 Lens 16a, 16b Optical surface 20 Low coherence light source 22 Light source 30, 100 Interferometer 31 First coupler 32 Second coupler 33 First circulator 34 Second circulator 35 Optical path length adjustment unit 35a Collimator lens 35b Optical path length adjustment mirror 35c Mirror drive unit 36 Phase modulator 37 Balance detector 40, 40-2 Measurement optical system 41 Half mirror 42 Collimeter lens 43 Image sensor 44 Scanning mirror 45 Condensing lens 46 Objective lens 47 Spatial filter 48 Scanning surface 50 Scanning unit 52 Mirror control unit 54 Tilt angle sensor 60 Control unit 62 Measuring unit 64 Memory 70 Objective lens control unit 80 Display 100 Interferometer 124 Beam splitter 125 Circulator 110 No. Collimeter lens 120 Beam splitter 200 Collimeter lens 210 Adapter lens 220 Variable focus lens 130 Reflective mirror 140 Image sensor 142 Photodetector CL1 Combined light CL2 Combined light FB1, FB2, FB3, FB4 Optical fiber FB1a, FB2a End L Low coherence light Lo Reference axis Lp Optical axis ML1, ML2 Measurement light RL1, RL2, RL3 Reference light S10 Step S12 Step S14 Step S16 Step S18 Step S20 Step S22 Step S24 Step S26 Step S30 Step S32 Step S34 Step S36 Step S40 Step S42 Step S44 Step S46 Step Si surface θ1, θ2 Scanning angle

Claims (16)

An eccentricity measuring device that measures the amount of eccentricity of the optical surface to be measured of a lens.
A light source that emits measurement light and
A measurement optical system for condensing the measurement light, the first optical system, a measurement optical system having a bent portion for bending the optical path of the measurement light, and a measurement optical system.
A scanning control unit that changes the bending angle of the optical path of the measurement light using the bending portion and scans the condensing position of the measurement light.
A detection unit that detects intensity information of the reflection measurement light, which is the measurement light reflected by the optical surface to be measured, and a detection unit.
A measuring unit for measuring the amount of eccentricity of the optical surface to be measured is provided.
The detection unit detects the intensity information at each of the plurality of the bending angles when the bending angle is changed by the scanning control unit.
The measuring unit is an eccentricity measuring device that measures the amount of eccentricity of the optical surface to be measured based on the strength information at each of the plurality of bending angles and the bending angle information of the bending portion. The focal length of the first optical system is variable,
The eccentricity measuring apparatus according to claim 1, wherein the condensing position of the measurement light is changed by changing the focal length of the first optical system. The first optical system has a first lens.
The focal length of the first lens is changed by electrically controlling the focal length of the first lens itself.
The eccentricity measuring apparatus according to claim 1, wherein the focusing position of the measurement light is changed by changing the focal length of the first lens. The second or third aspect of the measurement optical system, wherein the measurement optical system has a second optical system that changes the maximum value of the refractive power of the first optical system and the minimum value of the refractive power of the first optical system. Eccentricity measuring device. The eccentricity measuring apparatus according to any one of claims 1 to 4, wherein the measurement light emitted from the light source is incident on the first optical system via the bent portion. The eccentricity measuring apparatus according to any one of claims 1 to 4, wherein the measurement light emitted from the light source is incident on the bent portion via the first optical system. It has a collimator lens that makes the measurement light parallel.
The eccentricity measuring apparatus according to any one of claims 1 to 6, wherein the measurement light emitted from the light source is incident on the first optical system via the collimator lens. A first demultiplexing unit that separates the optical path of the measurement light and the optical path of the reflection measurement light is provided.
The eccentricity measuring device according to any one of claims 1 to 7, wherein the detection unit detects the reflection measurement light emitted from the first demultiplexing unit. The detection unit detects the amount of light of the reflection measurement light as the intensity information.
The measuring unit measures the amount of eccentricity of the optical surface to be measured by using the bending angle information when the amount of the reflected measurement light reaches the maximum value, any one of claims 1 to 8. Eccentricity measuring device according to. A second demultiplexing section that demultiplexes the reference light from the measurement light,
A wave junction portion that combines the reflection measurement light and the reference light is provided.
The light source is a low coherence light source that emits low coherence light as the measurement light.
The eccentricity measuring device according to any one of claims 1 to 8, wherein the detection unit detects the amount of the combined wave light combined at the combined wave unit as the intensity information. A second demultiplexing section that demultiplexes the reference light from the measurement light,
A wave junction portion that combines the reflection measurement light and the reference light is provided.
The light source is a low coherence light source that emits low coherence light as the measurement light.
The eccentricity measuring device according to any one of claims 1 to 8, wherein the detection unit detects the distribution of the amount of light intensity of the combined wave light combined at the combined wave unit as the intensity information. The eccentricity measuring apparatus according to claim 10 or 11, further comprising an optical path length adjusting unit for adjusting the optical path length of one of the reflection measurement light and the reference light before being combined by the wave combining unit. An eccentricity measuring device that measures the amount of eccentricity of the optical surface to be measured of a lens.
A low coherence light source that emits low coherence light as measurement light,
A demultiplexer that demultiplexes the low coherence light into measurement light and reference light,
A first optical system that changes the condensing position of the measurement light, a measurement optical system that has a scanning unit, and
A scanning control unit that controls the scanning unit and changes the condensing position of the measurement light.
A wave junction portion that combines the reflection measurement light, which is the measurement light reflected by the optical surface to be measured, and the reference light.
A detection unit that detects the intensity information of the combined wave light combined by the combined wave unit, and a detection unit.
A measuring unit for measuring the amount of eccentricity of the optical surface to be measured is provided.
The detection unit detects the intensity information at each of the plurality of collection positions of the measurement light when the collection position of the measurement light is changed by the scanning unit.
The measuring unit is an eccentricity measuring device that measures the amount of eccentricity of the optical surface to be measured based on the intensity information at each of the condensing positions of the plurality of measurement lights and the scanning information by the scanning unit. The eccentricity measuring apparatus according to claim 13, further comprising an optical path length adjusting unit for adjusting the optical path length of one of the reflection measurement light and the reference light before being combined by the wave combining unit. A low coherence light source that emits low coherence light,
A demultiplexer that demultiplexes the low coherence light into measurement light and reference light,
Of the plurality of optical surfaces of the lens, an objective lens that condenses the measurement light on a scanning surface on which the design curvature center position of the optical surface to be measured exists, and a position that condenses the measurement light by the objective lens. A measurement optical system having a scanning unit for moving the lens on the scanning surface, and
A wave junction portion that combines the measurement light reflected by the optical surface of the lens and the reference light, and
An optical path length adjusting unit that adjusts the optical path length of one of the measured light and the reference light before being combined by the combined wave unit according to the position of the optical surface to be measured.
A phase modulation unit that phase-modulates one of the measurement light and the reference light before being combined by the combine unit,
A detection unit that detects the combined wave light combined by the combined wave unit,
A measuring unit that measures the amount of eccentricity of the curvature center position of the optical surface to be measured with respect to the design curvature center position based on the detection output obtained from the detection unit and the scanning information by the scanning unit.
Eccentricity measuring device equipped with. The low coherence light emitted from the low coherence light source is demultiplexed into the measurement light and the reference light, and the measurement light and the reference light are used to design the optical surface to be measured among the plurality of optical surfaces of the lens. An eccentricity measuring method for measuring the amount of eccentricity at the center of curvature of the optical surface to be measured with respect to the center of curvature above.
A step of combining the measurement light reflected on the optical surface of the lens by the combiner with the reference light to generate the combined wave light.
A step of adjusting the optical path length of one of the measured light and the reference light before being combined by the combined wave portion by the optical path length adjusting unit according to the position of the optical surface to be measured.
A step of phase-modulating one of the measurement light and the reference light before being combined by the combiner by the phase modulator.
It is a step of condensing the measurement light on the scanning surface where the design curvature center position of the optical surface to be measured exists by the objective lens and irradiating the optical surface of the lens. The step of irradiating the optical surface of the lens with the measurement light while moving the position for condensing the light on the scanning surface.
The step of acquiring the detection output corresponding to the combined wave light generated by the combined wave unit by the detection unit, and
Based on the detection output acquired by the detection unit and the scanning information by the scanning unit, the measurement unit measures the amount of eccentricity of the curvature center position of the optical surface to be measured with respect to the design curvature center position. ,
Eccentricity measuring method including.

Images