KR200372906Y1 - Apparatus for measuring lens focal length and eccentricity - Google Patents

Abstract

The present invention is a device for measuring the lens to be measured (L) in a straight optical path on the rail (10) by the nodal slide method: installed on the bench (10) so as to be movable and rotatable, the lens to be measured (L) A lens holder 50 accommodating therein; A collimator 60 spaced apart and fixed to one side of the lens holder 50 and having an optical fiber bundle 65; A microscope 70 mounted to the other side of the lens holder 50 and having an optical fiber bundle 75; And control means for acquiring an image of the microscope 70 by the CCD camera 80 and displaying the image on the monitor 90.

The lens holder 50 can be coaxially rotated through the optical path, and the image is displayed on the monitor using the optical fiber light emitting section as an object, thereby improving the ease and reliability of measurement as well as being economical and focusing compared to existing equipment. In addition to distance, eccentricity measurement can be performed.

Description

Apparatus for measuring lens focal length and eccentricity

The present invention relates to a lens focal length and eccentric measuring device, and more specifically, to improve the ease and reliability of measurement in measuring the effective focal length and the back focal length of the lens It relates to a focal length and an eccentric measuring device.

Lenses completed through a series of processes at the manufacturing site are evaluated for their refractive index, focal length, resolution, magnification, various aberrations, and interference fringes. Among them, the focal length is measured by Neutralization Test, Auto-Collimation Technique, Geneva Gauge (Spherometer), Newtonian Distances, Reciprocal Magnification Method, and Nodal Slide. There is this. Focal length measurement using dual nodal slides is more accurate than other methods and can measure a wider range of focal lengths, making it the best choice for measuring the performance of high-precision lenses.

1 is a schematic view showing a conventional measuring device.

The conventional nodal slide includes a lens holder 20 for receiving a lens L to be measured on a rail 10, a collimator 30 for generating parallel light, and a microscope 40 for viewing with an eyepiece 46. It is provided in a straight line. The lens holder 20 and the microscope 40 can be moved finely in units of micrometers by the respective stages 22 and 42, and the distance moved to focus the linear scale mounted on the rear of the rail 10 ( 15) can be measured.

At this time, the collimator 30 is provided with a light source 35 and a chart 38, and another light source 45 and a chart 48 are installed in the microscope 40. The chart 38 of the collimator 30 is used for measuring the rear focal length and the effective focal length of the lens L, and the light irradiated from the light source 35 is applied to the chart 38, the pinhole, and the collimation lens. Pass through to parallel light and pass through the lens to be examined L to form an image. The chart 48 of the microscope 40 is used to measure the focal length behind the lens L to be measured, and the light from the light source 45 passes through the chart 48 and enters the lens holder 20. . There are arbitrary patterns in the charts 38 and 48 to block light in portions with patterns and to pass only light in portions without patterns. The patterns of the charts 38 and 48 are precisely manufactured through a semiconductor process, but the chart 48 of the microscope 40 has a relatively low precision, but both are expensive.

The object of the present invention is to provide a lens focal length and eccentric measuring device that can measure the optical fiber shape as an object while omitting the collimeta chart and microscope chart while replacing the light source of the collimator and microscope with an optical fiber.

Another object of the present invention is to enable eccentric measurement as well as focal length using mutual structural similarity.

Another object of the present invention is to mount a camera on a microscope and display an image on a monitor to enable more accurate measurement.

1 is a schematic view showing a conventional measuring device,

2 is a schematic view showing a measuring apparatus according to the present invention,

3 is a partial cross-sectional view showing a modification of the lens holder according to the present invention.

<Explanation of Signs of Major Parts of Drawings>

10: rail 15: linear scale

20, 50: lens holder 30, 60: collimator

40, 70: microscope 52, 72: stage

54: rotor 55: auxiliary ring

56: bearing 65, 75: optical fiber bundle

80: CCD camera 85: relay lens

90: monitor

In order to achieve this object, the present invention provides a device for measuring the lens to be measured L in a straight optical path on the rail 10 by a nodal slide method: installed on the bench 10 so as to be movable and rotatable, A lens holder 50 accommodating the lens L to be measured therein; A collimator 60 spaced apart and fixed to one side of the lens holder 50 and having an optical fiber bundle 65; A microscope 70 mounted to the other side of the lens holder 50 and having an optical fiber bundle 75; And control means for acquiring an image of the microscope 70 by the CCD camera 80 and displaying the image on the monitor 90.

As a modification of the present invention, the lens holder 50 may further include an auxiliary ring 55 surrounding the outer circumferential surface up and down through the bearing 56 to be rotatable coaxially with the optical path.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment according to the present invention.

2 is a schematic view showing a measuring apparatus according to the present invention, Figure 3 is a partial cross-sectional view showing a modification of the lens holder according to the present invention.

The present invention relates to an apparatus for measuring the focal length of the lens to be measured L in a straight optical path on the rail 10 in a nodal slide manner. In order to exclude expensive charts 38 and 48 according to the purpose of the present invention, a structure capable of obtaining a sufficient amount of light while generating a pattern by a light source itself should be introduced. The collimator 60 and the microscope 70 are arranged on both sides of the lens holder 50 on the rail 10 so that a straight optical path is formed.

According to the present invention, a lens holder 50 accommodating the lens to be measured L is installed on the rail 10 so as to be movable and rotatable. The lens holder 50 is installed on the rail 10 via the stage 52 and is movable in micrometers. The lens holder 50 is installed via the rotor 54 on an axis extending vertically and at a predetermined left and right angles. Rotation (rotation) is possible.

Further, according to the present invention, the collimator 60 having the optical fiber bundle 65 is fixed to be spaced apart from one side of the lens holder 50, and the microscope 70 having the optical fiber bundle 75 is the lens holder. It is mounted to the other side of the moveable 50. The collimator 60 is fixed so as not to move on the rail 10, and the microscope 70 is installed so as to be able to move finely through the stage 72. Conventional light sources 35 and 45 generally use lamps, such as incandescent lamps, but the present invention introduces fiber bundles 65 and 75. The optical fiber bundles 65 and 75 are bound to the amount of illuminance required by the collimator 60 and the microscope 70, respectively, but if the quantity is small, it is advantageous to reduce the measurement error by maintaining the point light source. Do.

When the optical fiber is used for the light source of the collimator 60 according to the present invention, since the cross-sectional shape of the optical fiber bundle is directly used as a chart, the rear focal length can be measured without a high cost chart. In addition to the above cost savings, sufficient light can be obtained, resulting in a brighter and larger image, resulting in higher measurement accuracy. In the same manner, by replacing the chart image with an optical fiber in the light source of the microscope 70, the back focal length and the effective focal length can be measured inexpensively and precisely.

In addition, according to the present invention includes a control means for obtaining the image of the microscope 70 by the CCD camera 80 and display on the monitor (90). The CCD camera 80 is coupled to the eyepiece 46 (see FIG. 1) position of the microscope 70 via a relay lens 85. The image of the CCD camera 80 is displayed by a monitor or separate equipment. When the operator measures the rear focal length and the effective focal length while closely contacting the eyepiece 46 and observing an image as in the related art, eye fatigue is increased due to a long time operation. In addition, if the rotation of the lens holder 50 to observe the rotation of the image accurately, the measurement error becomes larger.

In order to prevent such measurement error and obtain more accurate values, the relay lens 85 and the CCD camera 80 are used instead of the eyepiece 46 of the microscope 70 to output an image through the monitor 90. In the case of the 10x eyepiece, the magnification is 10x, but the CCD camera 80 is enlarged to 40x (monitor size / sensor size) when the size of the CCD sensor is 1/3 "and the monitor 90 is 14". Can be seen. Compared to eyepiece measurement, the monitor can be measured in a comfortable environment, reducing operator fatigue and minimizing operator error.

Normally, the focal length meter has the same structure as the eccentric meter. Although not shown, the eccentric measuring instrument is composed of a light source, a chart, a lens holder, and a microscope, and measures the eccentricity according to the degree of movement of the chart image formed on the microscope when the lens of the lens holder is rotated. The lens rotates about the optical path through the lens with the central axis, and the degree of eccentricity per division of the image on the microscope is inversely proportional to the distance between the lens and the microscope lens.

At this time, the lens holder 50 of the present invention is further provided with an auxiliary ring 55 surrounding the outer circumferential surface up and down through the bearing 56 is rotatable coaxially with the optical path. The structure in which the lens holder 50 is mounted on the rotor 54 of the vertical axis and rotates left and right is essential for effective focal length measurement. The present invention further includes a bearing 56 and an auxiliary ring 55 such that the lens holder 50 is rotatable about an optical path. The auxiliary ring 55 is installed to coaxially surround the outer circumferential surface of the cylindrical lens holder 50, so that the bearing 56 is interposed to assist the smooth rotation of the lens holder 50. When the rotor 54 is fixed to the lower end of the auxiliary ring 55, the vertical axis rotation and the optical path coaxial rotation of the lens holder 50 are possible.

The focal length measurement using the device according to the present invention is as follows.

1) Attach the lens to be inspected (L) to the lens holder (50). At this time, the image surface of the inspection lens (L) is to face the microscope (70).

2) The optical fiber bundle 65 of the collimator 60 is turned off, and the optical fiber bundle 75 of the microscope 70 is turned on to bring the microscope 70 closer to the lens. Measurement errors can occur due to the reflections on the surface other than the outermost surface, but you can make accurate measurements by drawing a pattern with a pen on the lens surface.

3) Close the microscope to the lens until the optical fiber bundle 75 of the microscope 70 is clearly seen, and then record the position A of the microscope 70 from the linear scale 15.

4) The optical fiber bundle 65 of the collimator 60 is turned on, the optical fiber bundle 75 of the microscope 70 is turned off, and the microscope 70 is moved away from the lens.

5) Move the optical fiber bundle 65 of the collimator 60 until it is clearly visible, and then record the position B of the microscope 70 from the linear scale 15.

6) | Microscope Position B-Microscope Position A | Calculate to find the rear focal length of the lens to be inspected (L).

Subsequently, the effective focal length measurement is performed in the following order.

1) The reference lens is mounted on the lens holder 50. Although not shown, the reference lens uses a plane chart.

2) Turn on the light source of the collimator 60, turn off the light source of the microscope 70, and bring the microscope 70 close to the lens until the optical fiber bundle 65 is clearly seen.

3) Rotating the lens holder 50 to the left and right with the rotor 54 to observe the direction in which the image of the optical fiber bundle 65 moves. If the reference lens is moved in the same direction, the position of the reference lens is biased toward the collimator 60, so that the lens holder 50 is moved in the opposite direction to the collimator 60 using the stage 52. The microscope 70 is moved in the same direction until the image of the optical fiber bundle 65 is clearly seen, and then the rotation direction of the lens holder 50 and the rotation direction of the image of the collimator 60 are observed. If the lens holder 50 moves in the opposite direction, the lens holder 50 moves in the collimator 60 direction and is observed. Even when the reference lens is positioned at the nodal point, the optical fiber bundle of the collimator 60 is rotated even when the lens holder 50 is rotated. The image of 65 is immovable. The microscope position A at this time is recorded.

4) Remove the reference lens and attach the inspected lens (L) to position the inspected lens (L) at the nodal point in the same manner as 2) to 3) and then image the optical fiber bundle 65 of the collimator 60. Record the microscope position (B) where you can see clearly.

5) | Microscope position B-microscope position A | Calculate the effective focal length of the lens to be inspected (L).

In the conventional case, the size of the chart image shown to the examiner can be adjusted by adjusting the magnification of the objective lens of the microscope 40 used when measuring the effective focal length and the rear focal length. Of course, the high magnification objective lens makes the image large, but it is hard to find the image, and the low magnification objective lens makes it easy to measure, but the measurement error increases. On the other hand, in the present invention, since it is displayed on the monitor 90, it is convenient to find an image or to continue the measurement work.

According to the construction and operation of the present invention described above, the lens holder and the optical fiber shape that can be rotated in the vertical axis and the optical path are made into an object, and the image is displayed on the monitor. There is a possible effect.

Claims (2)

In a device for measuring the lens under measurement L in a straight optical path on the rail 10 by a nodal slide method: A lens holder (50) installed on the bench (10) to be movable and rotatable and accommodating a lens (L) therein; A collimator 60 spaced apart and fixed to one side of the lens holder 50 and having an optical fiber bundle 65; A microscope 70 mounted to the other side of the lens holder 50 and having an optical fiber bundle 75; And Control means for acquiring the image of the microscope (70) by the CCD camera (80) and display on the monitor (90). The method of claim 1, A lens focal length and eccentricity measuring device, characterized in that the lens holder (50) through the bearing 56 and further comprises an auxiliary ring (55) surrounding the outer circumferential surface up and down to be rotated coaxially with the optical path.