JP2006091725A - Optical apparatus including laser light source, and method for adjusting the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical apparatus capable of simply adjusting the position of an optical element with respect to an optical axis. <P>SOLUTION: The optical apparatus includes a laser light source unit (2), a laser light source unit housings (3 and 4) and a first optical element housing (5). The laser light source unit includes a laser light source (1) and has a cylindrical shape having an axis of symmetry of revolution which coincides with an optical axis. The laser light source unit housing has a cylindrical hollow part which is engaged with the laser light source and is provided with a first member (3) having a plane tilted by a predetermined angle with respect to the optical axis when the laser light source unit is engaged. The first optical element housing includes the optical element and is provided with a plane tilted by a predetermined angle with respect to the optical axis. The position of the laser light source unit is adjustable in the cylindrical hollow part in the turning direction around the axis of symmetry of revolution which coincides with the optical axis direction and the optical axis. The position of the first optical element housing is adjustable by sliding the plane tilted by a predetermined angle with respect to the optical axis. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical device including a laser light source and an adjustment method thereof. In particular, the present invention relates to an optical device including a semiconductor laser as a laser light source and a lens as an optical element, and an adjustment method thereof.

  Semiconductor lasers as laser light sources are widely used in various fields in combination with various optical elements.

  4 and 5 show optical path diagrams of horizontal and vertical cross sections of an optical system of a light source part of a laser beam printer using a semiconductor laser. In general, the emission angle of laser light from a semiconductor laser is wide in the vertical direction and narrow in the horizontal direction with respect to the active layer. 4 and 5, the first lens arranged at a position close to the light source has a beam shaping function that aligns the horizontal and vertical diameters in the cross section of the light beam perpendicular to the optical axis. The second lens disposed on the opposite side of the first lens from the light source is a collimator lens.

  FIG. 6 shows an optical system of a laser beam printer including a semiconductor laser, a first lens, and a second lens as an incident optical system. The optical system of the laser beam printer includes a polygon mirror and a scanning optical system in addition to the incident optical system. As described above, the incident optical system shapes the diffused light from the semiconductor laser into a parallel light. The polygon mirror changes the direction of the beam. The scanning optical system forms an image of the beam at a desired position on the image plane.

  The incident optical system including the above-described semiconductor laser is widely used in an optical pickup system of an optical storage device in addition to a laser beam printer.

  FIG. 7 shows optical path diagrams of a vertical cross section and a horizontal cross section of an optical coupling element for coupling a laser beam from a semiconductor laser as a laser light source to an optical fiber. The condensing position is the position of the end face of the optical fiber. The optical coupling element has a beam shaping function and a light condensing function for aligning the horizontal and vertical diameters in a light beam cross section perpendicular to the optical axis.

  In the optical system including the semiconductor laser and the optical element described above, the following adjustment is required for the optical element.

Optical axis adjustment of optical element (position adjustment in a plane perpendicular to the optical axis)
Position adjustment of the optical element in the optical axis direction Position adjustment of the optical element in the rotational direction around the optical axis Adjustment of the tilt of the optical element with respect to the optical axis Here, it should be noted that the optical element is perpendicular to the optical axis. Since it has a beam shaping function that aligns the horizontal and vertical diameters of the light beam cross section, it has a rotationally asymmetric shape when the optical axis is the rotational axis. For this reason, the positional adjustment of the semiconductor laser and the optical element in the rotational direction around the optical axis is particularly important.

  Furthermore, as the optical resolution of laser printers and the density of optical storage devices increase, the accuracy required for optical systems is also increasing. For this reason, the above-mentioned position adjustment between the semiconductor laser and the optical element is required to have higher accuracy than before.

  For example, Patent Document 1 (FIGS. 1 and 8 to 11th paragraph, etc.), Patent Document 2 (FIGS. 1 and 9 to 10th paragraph, etc.), Patent Document 3 and the like are disclosed in Patent Document 1 (FIGS. 1 and 8 to 11th paragraph). (Paragraphs 2 to 3 and 23 to 31), Patent Document 4 (paragraphs 6 and 54 to 59), and Patent Document 5 (paragraphs 5 to 6 and 50 to 58). However, these conventional devices or methods do not allow all of the above adjustments.

Japanese Patent Laid-Open No. 5-47010 JP-A-6-270074 JP 11-258535 A JP 2000-292724 A JP 2000-314844 A

  Optical axis adjustment of laser light source and optical element (position adjustment in a plane perpendicular to the optical axis), position adjustment of laser light source and optical element in optical axis direction, laser light source and optical element around optical axis There is a need for an optical apparatus including a laser light source and an optical element that can easily perform all of the positional adjustment in the rotation direction and the inclination adjustment of the laser light source and the optical element with respect to the optical axis.

  An optical device including a laser light source according to the present invention includes a laser light source unit, a laser light source unit housing, and a first optical element housing. The laser light source unit includes a laser light source and has a cylindrical shape having an axis of rotational symmetry that coincides with the optical axis. The laser light source unit housing has a cylindrical hollow portion that fits with the laser light source, and includes a first member that has a surface having a certain angle with respect to the optical axis when the laser light source unit is fitted. The first optical element housing includes an optical element and includes a surface having the predetermined angle with respect to the optical axis. The laser light source unit is configured to be position-adjustable in the direction of the optical axis and the rotational direction around the rotationally symmetric axis that coincides with the optical axis in the cylindrical hollow portion of the first member. The first optical element housing is configured so that the position of the first optical element housing can be adjusted with respect to the laser light source unit housing by sliding the surface having the predetermined angle with respect to the optical axis.

  A method for adjusting an optical device according to the present invention adjusts an optical device including a laser light source unit, a laser light source unit housing, and a first optical element housing. The laser light source unit includes a laser light source and has a cylindrical shape having an axis of rotational symmetry that coincides with the optical axis. The laser light source unit housing has a cylindrical hollow portion that fits with the laser light source, and includes a first member that has a surface having a certain angle with respect to the optical axis when the laser light source unit is fitted. The first optical element housing includes an optical element and includes a surface having the predetermined angle with respect to the optical axis. A method of adjusting an optical device according to the present invention includes a step of fitting a laser light source unit into a cylindrical hollow portion of a first member, and observing a point image of a wavefront with an optical axis as a Z axis. Adjusting the positions of the entire optical device in the X-axis direction and the Y-axis direction so that the center is aligned with the center of the image. Further, wavefront aberration is measured, and the position of the first optical element housing in the X-axis direction and the Y-axis direction, the position of the laser light source unit in the Z-axis direction, and the rotational position of the laser light source unit around the Z-axis based on the measurement result A step of adjusting.

  According to the present invention, through the first laser light source unit housing, the position of the optical element in the plane perpendicular to the optical axis, the position adjustment in the optical axis direction, the position adjustment in the rotational direction around the optical axis, and Tilt adjustment with respect to the optical axis can be easily performed.

  According to an embodiment of the present invention, the constant angle of the first laser light source unit housing is 90 degrees.

  Therefore, it is possible to easily adjust the position of the laser light source and the optical element in the plane perpendicular to the optical axis.

  According to another embodiment of the present invention, the first optical element housing includes a base, and the surface having the constant angle is a surface of the base.

  According to another embodiment of the present invention, the first optical element housing includes a tilt adjusting mechanism with respect to the surface having the constant angle.

  According to another embodiment of the present invention, the first optical element housing includes a base and a tilt adjusting mechanism with respect to the surface having the constant angle, and the surface having the constant angle is a surface of the base, and the tilt adjusting mechanism. The inclination of the portion other than the base is adjusted with respect to the base.

  Therefore, it is possible to easily adjust the inclination of the optical element with respect to the optical axis.

  According to another embodiment of the present invention, the laser light source unit housing further includes a second member having a surface having a constant angle with respect to the optical axis when the laser light source unit is fitted to the first member. Prepare. The apparatus includes an optical element, and further includes a second optical element housing including the surface of the second member at the constant angle with respect to the optical axis. The second optical element housing is configured so that the position of the second optical element housing can be adjusted with respect to the laser light source unit housing by sliding the surface of the second member at a certain angle with respect to the optical axis.

  Therefore, the position of the two optical elements can be adjusted via the laser light source unit housing.

  According to another embodiment of the present invention, the constant angle of the second member is 90 degrees.

  Therefore, it is possible to easily adjust the position of the laser light source and the optical element in the plane perpendicular to the optical axis.

  According to another embodiment of the invention, the second optical element housing includes a base.

  According to another embodiment of the present invention, the second optical element housing includes a tilt adjusting mechanism with respect to the surface of the constant angle of the second member.

  According to another embodiment of the present invention, the second optical element housing includes a tilt adjustment mechanism with respect to the surface of the constant angle of the base and the second member.

  Therefore, it is possible to easily adjust the inclination of the optical element with respect to the optical axis.

  With reference to FIG. 1, the structure of the optical apparatus including the laser light source of the present invention will be described. The optical device including the laser light source 1 of the present invention includes a laser light source unit 2, laser light source unit housings 3 and 4, and a first optical element housing 5.

  The laser light source unit 2 includes the laser light source 1 and has a cylindrical shape having an axis of rotational symmetry that coincides with the optical axis.

  The laser light source unit housing includes a first member 3 having a hollow portion that fits into the laser light source unit 2, and the first member 3 is fixed with respect to the optical axis when the laser light source unit 2 is fitted. A surface having an angle is provided. The first optical element housing 5 includes an optical element, and includes a surface having a constant angle with respect to the optical axis corresponding to a surface having a constant angle with respect to the optical axis of the first member 3. In the present embodiment, the first optical element housing 5 includes a base 6, and the base 6 includes a surface having the constant angle that abuts on the surface having the constant angle of the first member 3. The base 6 has a disk shape, for example. In the present embodiment, the constant angle is 90 degrees.

  The laser light source unit housing includes a second member 4. The second member 4 includes a surface having a certain angle with respect to the optical axis when the laser light source unit 2 is fitted to the first member 3. In the present embodiment, the constant angle is 90 degrees. The first member 3 and the second member 4 are integrally formed.

  The first optical element housing 5 and the base 6 are fixed by screws 9 and 10, for example. By providing, for example, an adjusting screw 11 around the second member 4 at the height of the first optical element housing 5, the first optical element housing 5 can be arranged in a plane perpendicular to the optical axis. The position can be adjusted. When the first optical element housing 5 is moved in a plane perpendicular to the optical axis by the adjusting screw 11, the first optical element housing 5 and the base 6 are 90 degrees to the optical axis of the first member 3. Slide on the surface.

  Here, the laser light source unit 2 is configured so that the position of the hollow portion of the first member 3 can be adjusted in the optical axis direction and the rotational direction around the rotational symmetry axis that coincides with the optical axis. Adjustment in the optical axis direction is performed by the helicoid stage 24. Position adjustment in the rotational direction around the rotational symmetry axis that coincides with the optical axis is performed by the rotary stage 23. The laser light source unit 2 is supported by a support base 26 on the helicoid stage 24.

  In the present embodiment, the optical device further includes a second optical element housing 7 and a base 8. The base 8 includes a bottom portion and a flange portion. A second optical element housing 7 is disposed at the bottom of the base 8. The lower surface of the flange portion of the base 8 is configured to contact the upward surface of the second member 4. The upward surface of the second member 4 is configured to form an angle of 90 degrees with the optical axis.

  The adjustment screw 13 fixes the base 8 to the second member 4. The adjusting screw 13 is also used for adjusting the height and inclination of the second optical element housing 7 and the base 8. By providing, for example, an adjustment screw 11 around the second optical element housing 7, the position of the second optical element housing 7 in a plane perpendicular to the optical axis can be adjusted. When the second optical element housing 7 is moved in the plane perpendicular to the optical axis by the adjusting screw 11, the second optical element housing 7 slides on the bottom surface of the base 8.

  The laser light source 1 is a semiconductor laser and is preferably single mode. The wavelength is 350 to 1300 nm, mainly around 400 or 900 nm. Laser power can be up to 2W class. In this embodiment, it is a single mode semiconductor laser having an output of 200 mW and a wavelength of 940 nm.

  Next, a method for adjusting the optical device of the present invention will be described below.

  FIG. 2 shows a configuration of an adjustment system including the optical device of the present invention and a measurement optical system for measuring the wavefront of the laser beam. As will be described in detail below, the position of the laser light source and the optical element is adjusted by the optical device of the present invention while measuring the wavefront of the laser beam by the measurement optical system. The case where the laser beam emitted by the laser light source 1 is made parallel by the optical element will be described as an example. The diameter of the parallel laser beam is changed by allowing the parallel laser beam to pass through the lens 101 having the focal length F1 and the lens 103 having the focal length F2 which are arranged with an interval of the sum of the focal points. Specifically, the diameter of the parallel laser beam is F2 / F1 times. The diameter of the parallel laser beam is adjusted so as to match the area of the microlaser array 105 disposed behind.

  Next, wavefront measurement will be described. For the wavefront measurement, the Shack-Hartmann measurement method is used. In measurement, for example, reference light from a helium-neon light source 111 is incident on the microlens array 105. The microlens focal length of the microlens array 105 is 10,000 micrometers, and the arrangement pitch is 0.3 millimeters. Each microlens collects the incident reference light. A focus image is formed on a detector array (CCD) 109 using the imaging lens 107, and the position of each focus is recorded. Next, measurement light is incident on the microlens array 10 and a focus image is recorded in the same manner. A deviation amount between the focus position of the reference light and the focus position of the measurement light is obtained. Since the amount of deviation from the reference light represents the inclination of the wavefront, the wavefront of the beam light can be obtained by integrating the entire beam diameter.

  The aberration can be individually evaluated by expanding the measured wavefront displacement, that is, the wavefront aberration, with the Chernike coefficient. Specifically, the first term of the Chernike coefficient is the tilt of the X axis, the second term of the Chernike coefficient is the tilt of the Y axis, the third term of the Chernike coefficient is the defercus of the optical element, the fourth and fifth terms of the Chernike coefficient are astigmatism, and the Chernike coefficient. Coefficients 6 and 7 indicate coma aberration (positions of the front and back surfaces of the optical element, axial deviation between the semiconductor laser light source and the optical element, etc.), and the Cernike coefficient 8 indicates spherical aberration. The above-described processing for expanding the wavefront aberration to the Chernike coefficient is performed by a processor (not shown) connected to the detector array 109. The processor may be a personal computer, for example.

  Based on the result of the wavefront measurement described above, the positions of the laser light source unit 2, the first optical element housing 5 and the second optical element housing 7 through the laser light source unit housings 3 and 4 by the optical device of the present invention. Adjust the relationship.

  If the aberration is still not equal to or less than the target value, for example, λ / 4, even after adjusting the positional relationship among the laser light source unit 2, the first optical element housing 5, and the second optical element housing 7, the processing laser The aberration is further reduced by processing the shape of the wavefront correction plate 12 by the laser ablation processing method using the light source 113 and the processing condensing lens 115. Specifically, the wavefront of the semiconductor laser light that has passed through the first and second optical elements and the wavefront correction plate 12 is measured, and a contour map indicating the degree of phase advance is created. The portion of the wavefront correction plate corresponding to the place where the phase of this map is delayed is removed by laser ablation to adjust the phase. By using a resin wavefront correction plate, correction can be made even if the optical element is made of glass. Details of the laser ablation processing method are described in Japanese Patent No. 3085875 (method for forming an optical surface).

  The above adjustment procedure will be described with reference to the flowchart of FIG. In step S010, the laser light source unit 2 and the laser light source unit housings 3 and 4 are attached to the housing base 25 in FIG.

  In step S020, while observing the point image of the wavefront, the rotation stage 23 and the entire optical device are moved in the X-axis direction by the XY stage 21 of FIG. 1 so that the position of the wavefront point image is symmetrical left and right and up and down. The center of the laser light source is aligned with the measurement optical system by moving in the Y-axis direction. Further, the optical axis shift of the laser beam due to the mounting error of the semiconductor laser chip is adjusted by the tilt stage 22 of FIG.

  In step S030, the first optical element housing 5 and the base 6 are placed on a plane of 90 degrees with respect to the optical axis of the first member 3. The wavefront aberration is measured by the detector array 109. The rotation of the laser light source unit 2 is adjusted by the rotary stage 23 of FIG. 1 so that the Chernike coefficients 1 to 7 are minimized, and the adjustment screw 11 adjusts the X-axis direction and the Y-axis of the first optical element housing 5. Adjust the position of the direction.

  In step S040, the wavefront aberration is measured by the detector array 109. The height of the laser light source unit 2 with respect to the position of the first optical element housing 5 is adjusted by the helicoid stage 24 of FIG. 1 so as to minimize the third term of the Chernike coefficient.

  In step S050, it is determined whether astigmatism adjustment is necessary. If necessary, the process proceeds to step S060, and if not necessary, the process proceeds to step S070. In step S060, the optical element unit 5 is tilted with respect to the base 6 in the X-axis direction or the Y-axis direction by the tilt adjusting screw 10 so that the Chernike coefficients 4 and 5 are minimized.

  Thereafter, the process returns to step S030, and the position of the first optical element housing 5 and the height of the laser light source unit 2 are adjusted again.

  In step S070, the second optical element unit 7 and the base 8 are placed on a surface at 90 degrees with respect to the optical axis of the second member 4. The wavefront aberration is measured by the detector array 109. The position of the second optical element housing 7 in the X-axis direction and the Y-axis direction is adjusted by the adjusting screw 11 so that the Chernike coefficients 1 to 7 are minimized.

  In step S080, the wavefront aberration is measured by the detector array 109. The height of the base 8 relative to the second member 4 is adjusted by the adjusting screw 13 so as to minimize the third term of the Chernike coefficient.

  In step S090, it is determined whether astigmatism adjustment is necessary. If necessary, the process proceeds to step S100, and if not necessary, the process proceeds to step S110.

  In step S100, the second optical element housing and the base 8 are tilted with respect to the second member 4 in the X-axis direction or the Y-axis direction by the adjusting screw 13 so as to minimize the Chernike coefficients 4 and 5.

  Thereafter, the process returns to step S070, and the position and height of the second optical element housing 7 are adjusted again.

  In step S110, the laser light source unit 2 and the laser light source unit housings 3 and 4 are fixed with an adhesive such as a UV curable resin. Further, the first optical element unit 5 including the base 6, the second optical element unit 7 including the base 8, and the laser light source unit housings 3 and 4 are fixed with an adhesive such as a UV curable resin. Instead of using an adhesive such as a UV curable resin, it may be fixed by fusion by laser irradiation.

In step S120, the wavefront is measured, and it is determined whether correction by the wavefront correction plate is necessary. If necessary, the process proceeds to step S130. Exit if not needed. In Step S130, the aberration is further reduced by processing the shape of the wavefront correction plate 12 by the laser ablation processing method using the processing laser light source 113 and the processing condensing lens 115. Details of the laser ablation processing method are described in Japanese Patent No. 3085875 (method for forming an optical surface).

1 shows a configuration of an optical device including a laser light source according to an embodiment of the present invention. 1 shows a configuration of an optical system for adjusting an optical device including a laser light source according to an embodiment of the present invention. 5 is a flowchart illustrating an adjustment procedure of an optical device including a laser light source according to an embodiment of the present invention. The optical path figure of the horizontal direction cross section of the optical system of the light source part of the laser beam printer in which a semiconductor laser is used is shown. The optical path figure of the vertical direction cross section of the optical system of the light source part of the laser beam printer in which a semiconductor laser is used is shown. 1 shows an optical system of a laser beam printer. The optical path figure of the vertical direction cross section and the horizontal direction cross section of the optical coupling element for couple | bonding the laser beam from a semiconductor laser to an optical fiber is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 2 Laser light source unit 3 1st member of a laser light source unit housing 4 2nd member of a laser light source unit housing 5 1st optical element housing 7 2nd optical element housing

Claims (16)

An optical device including a laser light source,
A cylindrical laser light source unit including a laser light source and having a rotational symmetry axis coinciding with the optical axis;
A laser light source unit housing including a first hollow member having a cylindrical hollow portion to be fitted to the laser light source unit and having a surface having a certain angle with respect to the optical axis when the laser light source unit is fitted;
A first optical element housing that includes an optical element and has a plane at the predetermined angle with respect to the optical axis. Is configured so that the position can be adjusted in the direction of rotation around the rotational symmetry axis that coincides with
An optical device configured such that a position of the first optical element housing can be adjusted with respect to the optical axis by sliding a surface having the predetermined angle with respect to the optical axis. The laser light source unit housing further includes a second member having a surface with a certain angle with respect to the optical axis when the laser light source unit is fitted to the first member,
The apparatus further comprises a second optical element housing comprising an optical element and comprising the surface of the second member at the constant angle with respect to the optical axis;
An optical device configured such that a position of the second optical element housing can be adjusted with respect to the optical axis by sliding a surface of the second member at a certain angle with respect to the optical axis.   The optical apparatus according to claim 1, wherein the certain angle of the first member is 90 degrees.   The optical apparatus according to claim 1, wherein the first optical element housing includes a base, and the surface having the constant angle is a surface of the base.   The optical apparatus according to claim 1, wherein the first optical element housing includes a tilt adjusting mechanism with respect to the surface having the constant angle.   The first optical element housing includes a base and a tilt adjusting mechanism with respect to the surface having the constant angle, the surface having the constant angle is a surface of the base, and the tilt of the portion other than the base is tilted with respect to the base by the tilt adjusting mechanism. The optical device according to claim 1, wherein the optical device is adjusted.   The optical apparatus according to claim 2, wherein the constant angle of the second member is 90 degrees.   The optical apparatus according to claim 2, wherein the second optical element housing includes a base.   The optical device according to claim 2, wherein the second optical element housing includes a tilt adjustment mechanism for the surface of the second member with respect to the constant angle surface.   The optical device according to claim 2, wherein the second optical element housing includes a tilt adjustment mechanism with respect to the surface of the constant angle of the base and the second member. A cylindrical laser light source unit that includes a laser light source and has a rotationally symmetric axis that coincides with the optical axis, and a cylindrical hollow portion that fits into the laser light source unit, and light is received when the laser light source unit is fitted. A laser light source unit housing including a first member having a surface having a constant angle with respect to an axis; and a first optical element housing including an optical element and having the surface having the constant angle with respect to the optical axis. A method for adjusting an optical device comprising:
Fitting the laser light source unit into the cylindrical hollow portion of the first member;
Adjusting the positions of the entire optical apparatus in the X-axis direction and the Y-axis direction so that the center of the laser beam is aligned with the center of the image while observing the point image of the wavefront with the optical axis as the Z-axis;
Measure wavefront aberration and adjust the X-axis and Y-axis positions of the first optical element housing, the Z-axis position of the laser light source unit, and the rotational position of the laser light source unit around the Z-axis based on the measurement results And a step comprising: A cylindrical laser light source unit that includes a laser light source and has a rotationally symmetric axis that coincides with the optical axis, and a cylindrical hollow portion that fits with the laser light source. When the laser light source unit is fitted, the optical axis A laser light source unit housing comprising a first member having a surface with a constant angle with respect to the second member and a second member having a surface with a constant angle with respect to the optical axis, and an optical element, A method of adjusting an optical device comprising: a first optical element housing comprising a surface of constant angle; and a second optical element housing comprising an optical element and comprising the surface of constant angle of a second member. There,
Fitting the laser light source unit into the cylindrical hollow portion of the first member;
Adjusting the positions of the entire optical apparatus in the X-axis direction and the Y-axis direction so that the center of the laser beam is aligned with the center of the image while observing the point image of the wavefront with the optical axis as the Z-axis;
Measure wavefront aberration and adjust the X-axis and Y-axis positions of the first optical element housing, the Z-axis position of the laser light source unit, and the rotational position of the laser light source unit around the Z-axis based on the measurement results And steps to
Measuring wavefront aberration, and adjusting a position in the X-axis direction and a Y-axis direction and a position in the Z-axis direction of the second optical element housing based on the measurement result.   The method of claim 11, wherein the constant angle of the first member is 90 degrees.   The method of claim 11, further comprising adjusting the tilt of the first optical element housing relative to a surface at a constant angle with the optical axis of the first member.   The method of claim 12, wherein the constant angle of the first member and the constant angle of the second member are 90 degrees. Adjusting the inclination of the first optical element housing with respect to a surface having a constant angle with the optical axis of the first member and the inclination of the second optical element housing with respect to the surface having a constant angle with the optical axis of the second member; The method of claim 12 further comprising the step of adjusting.

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