JP5460502B2 - Method for designing optical component for laser beam shaping, and method for manufacturing optical component for laser beam shaping - Google Patents

Description

  The present invention relates to a laser beam shaping optical component for shaping laser beam intensity distribution into an arbitrary intensity distribution, and a design method and manufacturing of an aspheric lens type laser beam shaping optical component including a pair of aspheric lenses. It is about the method.

  In general, laser light often has an intensity distribution that is strongest near the center and gradually weakens toward the periphery, such as a Gaussian distribution. However, in laser processing or the like, a laser beam having a spatially uniform intensity distribution is desired. In this regard, Non-Patent Document 1 discloses a kaleidoscope type homogenizer as an optical component for laser light shaping that shapes the intensity distribution of laser light into a spatially uniform intensity distribution. No. 3 discloses an aspherical lens type homogenizer as a laser light shaping optical component that shapes the intensity distribution of laser light into a spatially uniform intensity distribution.

  The aspherical lens type homogenizer disclosed in Patent Document 1 includes a pair of aspherical lenses whose shapes are derived by a geometrical optical method, and the top hat-shaped intensity distribution of incident laser light having a Gaussian intensity profile. This is converted into an intensity distribution. On the other hand, the aspherical lens type homogenizer disclosed in Patent Document 2 includes a pair of aspherical lenses whose shapes are derived by a wave optical method, and the intensity distribution of incident laser light having an intensity profile of Gaussian distribution is a top hat. It is converted into a shape intensity distribution. In addition, the aspheric lens type homogenizer disclosed in Patent Document 3 includes a pair of aspheric lenses, and converts the intensity distribution of incident laser light having an intensity profile of Gaussian distribution into an intensity distribution of super Gaussian. is there.

U.S. Pat. No. 3,476,463 JP-A-10-153750 JP 2003-344762 A

Hiroshi Ito et al., “Development and application of beam homogenizer for surface treatment”, Laser Research, Laser Society of Japan, November 1994, Vol. 22, No. 11, p. 935-942

  In these Patent Documents 1 to 3, when designing the shape of a pair of aspherical lenses, a Gaussian distribution calculated using a Gaussian function, that is, a theoretical value, is used as the intensity distribution of incident laser light. However, actually, the intensity distribution of the laser light incident on the homogenizer is deviated from the theoretical value. Therefore, in the homogenizer design methods disclosed in Patent Documents 1 to 3, the laser beam shaping accuracy is low, and the desired intensity distribution of the shaped laser beam is distorted.

  Therefore, the present invention is an optical component for laser beam shaping that includes a pair of aspheric lenses, and is an optical component for laser beam shaping that can shape the intensity distribution of the laser beam into an arbitrary intensity distribution with higher accuracy. An object of the present invention is to provide a design method and a manufacturing method.

  The method of designing an optical component for laser beam shaping according to the present invention is a design of an optical component for laser beam shaping that includes a pair of aspherical lenses and generates emitted laser light in which the intensity distribution of incident laser light is shaped into a desired intensity distribution. In the method, an incident light measurement step of measuring an intensity distribution of incident laser light and an incident-side aspheric lens of a pair of aspheric lenses divide the measured intensity distribution of the incident laser light into a plurality of distribution directions. A plurality of outgoing light splitting regions obtained by splitting the intensity distribution of the outgoing laser light in the distribution direction in the incident light splitting step for obtaining the incoming light splitting region and the outgoing side aspherical lens of the pair of aspherical lenses, Adjusting the height of each of the plurality of incident light dividing regions according to the intensity distribution of the light and adjusting the width and position in the distribution direction to obtain the plurality of outgoing light dividing regions. And an optical path specifying step for specifying an optical path from the position in the distribution direction of the plurality of incident light split regions in the incident side aspheric lens and the position in the distribution direction of the corresponding plurality of output light split regions in the output side aspheric lens; And a shape determining step for determining the shape of the pair of aspheric lenses from the optical path.

  The method for manufacturing an optical component for laser beam shaping according to the present invention includes a pair of aspherical lenses and generates an emitted laser beam in which the intensity distribution of the incident laser beam is shaped into a desired intensity distribution. In the manufacturing method, the incident light measurement step of measuring the intensity distribution of the incident laser beam and the incident-side aspherical lens of the pair of aspherical lenses divide the measured intensity distribution of the incident laser beam in the distribution direction. In the incident light splitting step for obtaining a plurality of incident light splitting regions, and in the exit side aspherical lens of the pair of aspherical lenses, a plurality of outgoing light splitting regions obtained by dividing the intensity distribution of the outgoing laser light in the distribution direction, The output light for obtaining the plurality of output light division regions by adjusting the height of each of the plurality of incident light division regions according to the desired intensity distribution and adjusting the width and position in the distribution direction Splitting step, and an optical path specifying step for specifying the optical path from the position in the distribution direction of the plurality of incident light split regions in the incident side aspheric lens and the position in the distribution direction of the corresponding plurality of output light split regions in the output side aspheric lens And a shape determining step for determining the shape of the pair of aspheric lenses from the optical path, and a molding step for forming the pair of aspheric lenses based on the determined shape.

  According to these laser light shaping optical component design method and manufacturing method, the intensity distribution of incident laser light is measured, and the shape of a pair of aspheric lenses is designed based on the actually measured intensity distribution. In addition, a plurality of incident light split areas obtained by dividing the actually measured intensity distribution of the incident laser light are obtained, and the height and width of each of the plurality of incident light split areas are adjusted according to the desired intensity distribution of the emitted laser light. And determine the optical path from the position of the multiple incident light split areas on the incident side aspherical lens and the corresponding multiple positions of the outgoing light split areas on the output aspherical lens. Then, the shape of the pair of aspheric lenses is designed based on these optical paths. Therefore, it is possible to obtain an optical component for laser beam shaping that can shape the intensity distribution of the laser beam into an arbitrary intensity distribution with higher accuracy.

  In the outgoing light splitting step described above, the width and position of the plurality of incident light splitting regions in the distribution direction are set such that the energy of the plurality of incident light splitting regions and the corresponding energy of the plurality of outgoing light splitting regions are equal to each other. It is preferable to adjust and obtain a plurality of outgoing light division regions.

  In the above-described shape determination step, the shape of the incident-side aspheric lens is obtained from the optical path, the shape of the exit-side aspheric lens is obtained from the optical path, and the phase of the emitted laser light is aligned so that the emitted laser light becomes parallel light. It is preferable to obtain it.

  According to this, the incident-side aspherical lens capable of shaping the intensity distribution of incident laser light that is parallel light into a desired intensity distribution, and the phase of the laser light shaped by the incident-side aspherical lens are aligned, An exit-side aspherical lens that can be changed to parallel light can be obtained.

  Further, in the above-described shape determining step, in each of the plurality of incident light splitting regions, the angle of the optical path with respect to the principal axis perpendicular to the plane on the incident side of the incident side aspheric lens is determined on the exit side of the incident side aspheric lens. It is preferable to obtain the incident angle of the incident laser light with respect to the aspheric surface, and obtain the height difference of the aspheric surface of the incident side aspheric lens from the incident angle of the incident laser light with respect to the aspheric surface of the incident side aspheric lens.

  Further, in the shape determining step described above, in each of the plurality of outgoing light splitting regions, from the angle formed by the optical path with respect to the principal axis perpendicular to the outgoing side plane of the outgoing side aspherical lens, the incident side of the outgoing side aspherical lens is determined. It is preferable to obtain the exit angle of the exit laser light with respect to the aspheric surface, and obtain the height difference of the aspheric surface of the exit side aspheric lens from the exit angle of the exit laser light with respect to the aspheric surface of the exit side aspheric lens.

  In the incident light measurement step, the spread angle of the incident laser beam is further measured. In the shape determination step, the shape of the incident-side aspheric lens is obtained from the optical path and the spread angle of the measured incident laser beam. It is preferable.

  According to this, even if the incident laser light is non-parallel light having a divergence angle, it is possible to shape the intensity distribution of the incident laser light that is the non-parallel light into a desired intensity distribution with higher accuracy. A side aspherical lens can be obtained.

  Further, in the above-described shape determination step, it is preferable to obtain the shape of the emission side aspherical lens from the optical path and the desired spread angle of the emission laser light.

  According to this, even when it is desired to obtain non-parallel emission laser light having an arbitrary divergence angle, the phases of the laser light shaped by the incident-side aspheric lens are aligned, and the non-parallel light having a desired divergence angle is obtained. An exit-side aspherical lens that can be changed to parallel light with higher accuracy can be obtained.

  Further, in the above-described shape determination step, the angle formed by the optical path with respect to the principal axis perpendicular to the plane on the incident side of the incident-side aspherical lens and the measured spread angle of the incident laser light in each of the plurality of incident light dividing regions Thus, the incident laser beam is refracted incident laser light refracted on the plane of the incident-side aspheric lens, and the incident angle of the refractive incident laser beam with respect to the exit-side aspheric surface of the incident-side aspheric lens is obtained. It is preferable to obtain the height difference of the aspherical surface of the incident-side aspherical lens from the incident angle of the refractive incident laser light with respect to the aspherical surface of the spherical lens.

  In the shape determining step, the angle formed by the optical path with respect to the principal axis perpendicular to the emission side plane of the emission side aspherical lens and the desired spread angle of the emission laser beam in each of the plurality of emission light dividing regions. From the above, the refraction angle of the optical path with respect to the aspheric surface on the incident side of the exit side aspheric lens is obtained, and the height difference of the aspheric surface of the exit side aspheric lens is obtained from the refraction angle of the optical path with respect to the aspheric surface of the exit side aspheric lens. Is preferred.

  According to the present invention, a laser light shaping optical component including a pair of aspheric lenses, which can shape the intensity distribution of laser light into an arbitrary intensity distribution with higher accuracy. Can be obtained.

It is a block diagram which shows one Embodiment of an optical apparatus provided with the homogenizer of this embodiment. It is a flowchart which shows the design method and manufacturing method of the homogenizer which concern on the 1st Embodiment of this invention. It is a figure which shows an example of intensity distribution of incident laser light. It is a figure which shows an example of desired intensity distribution of an emitted laser beam. It is the schematic of intensity distribution division | segmentation of the incident laser beam in an incident light division | segmentation process. It is the schematic of desired intensity distribution division | segmentation of the emitted laser beam in an emitted light division | segmentation process. It is the schematic of adjustment of the width | variety and position from an incident light division area to an outgoing light division area in an outgoing light division process. It is the schematic of optical path identification in an optical path identification process. It is the schematic of shape determination in a shape determination process. It is an enlarged view of the incident side aspherical lens in FIG. It is a figure which shows an example of the shape of the incident side aspherical lens calculated | required in a shape determination process. FIG. 10 is an enlarged view of the emission side aspherical lens in FIG. 9. It is a figure which shows an example of the shape of the output side aspherical lens calculated | required in a shape determination process. It is a flowchart which shows the design method and manufacturing method of the homogenizer which concern on the 2nd Embodiment of this invention. It is the schematic of the shape determination in the shape determination process of 2nd Embodiment. It is the schematic of the intensity distribution division | segmentation of the incident laser beam and the desired intensity distribution division | segmentation of an emitted laser beam in the homogenizer design method and manufacturing method which concern on the modification of this invention. It is the schematic of the shape correction | amendment in the shape determination process in the design method and manufacturing method of the homogenizer which concerns on the modification of this invention. It is a figure which shows the measurement system for measuring the intensity distribution of the emitted laser beam of the aspherical lens in the homogenizer of a present Example. It is a figure which shows the measurement result of the intensity distribution of the incident laser beam of an aspherical lens in the homogenizer of a present Example, and an emitted laser beam. It is a figure which shows the design value and measurement result of intensity distribution of the emitted laser beam of an aspherical lens in the homogenizer of a present Example. It is a figure which shows the measuring system for measuring the intensity distribution of the emitted laser beam of the homogenizer of a present Example. It is a figure which shows the measurement result of intensity distribution of the emitted laser beam of the homogenizer of a present Example.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a designing method and a manufacturing method of a laser beam shaping optical component according to the invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  First, an optical apparatus that is used in a laser processing apparatus or the like and that includes a homogenizer (laser light shaping optical component) will be described. FIG. 1 is a configuration diagram showing an embodiment of the optical apparatus of the present embodiment. The optical device 1 includes a laser light source 2, a spatial filter 3, a collimating lens 4, and a homogenizer 10.

  The laser light source 2 is, for example, an Nd: YAG laser. The spatial filter 3 includes, for example, an objective lens having a magnification of 10 times and a pinhole having a diameter Φ = 50 μm. The collimating lens 4 is, for example, a plano-convex lens. As described above, the laser light emitted from the laser light source 2 passes through the spatial filter 3 and the collimating lens 4 so that the intensity distribution is shaped into a concentric Gaussian distribution.

The homogenizer 10 is for shaping the intensity distribution of laser light into an arbitrary shape. The homogenizer 10 includes a pair of aspheric lenses 11 and 12. In the homogenizer 10, the incident-side aspherical lens 11 functions to shape the intensity distribution of the laser light into an arbitrary shape, and the emission-side aspherical lens 12 aligns the phase of the shaped laser light so that parallel light or It functions to change to light having an arbitrary divergence angle. In the homogenizer 10, it is possible to generate the outgoing laser light Oo in which the intensity distribution of the incident laser light Oi is shaped into a desired intensity distribution by the aspheric shape design of the pair of aspheric lenses 11 and 12.
[First Embodiment]

  In the following, referring to FIG. 2, a homogenizer design method and manufacturing method according to the first embodiment of the present invention, which changes a parallel incident laser beam Oi into a parallel emitted laser beam Oo. The design method and manufacturing method will be described. FIG. 2 is a flowchart showing a homogenizer design method and manufacturing method according to an embodiment of the present invention.

  First, the intensity distribution of the incident laser beam Oi is measured (incident light measurement step) (S01). The intensity distribution can be measured using, for example, a beam profiler.

  Next, a desired intensity distribution of the emitted laser beam Oo is set (S02). In the present embodiment, the desired intensity distribution is set to a spatially uniform intensity distribution desired in the laser processing apparatus, that is, a super Gaussian distribution. Here, the desired intensity distribution needs to be set so that the energy (area of the desired intensity distribution) of the emitted laser beam Oo is equal to the energy (area of the intensity distribution) of the incident laser beam Oi. For example, the super Gaussian distribution of this embodiment may be set as follows.

In the following, in order to facilitate understanding of the principle of setting the desired intensity distribution of the emitted laser beam Oo, the intensity distribution of the incident laser beam Oi has a concentric Gaussian distribution (beam waist = 5) as shown in FIG. .6 mmat 1 / e ² , ω = 2.0 mm). Since the Gaussian distribution is expressed by the following equation (1), the energy within the radius of 6 mm of the incident laser light Oi is expressed by the following equation (2).


In this case, since the Gaussian distribution is rotationally symmetric about a radius of 0 mm, an aspheric shape is designed by one-dimensional analysis. Actually, the measured value in step S01 may be used as the energy of the incident laser beam Oi.

On the other hand, the desired intensity distribution of the emitted laser light Oo is set to a super Gaussian distribution (order N = 8, ω = 2.65 mm) as shown in FIG. Since the super Gaussian distribution is expressed by the following equation (3), in order for the energy within the radius of 6 mm of the emitted laser beam Oo to be equal to the energy of the incident laser beam Oi as expressed by the following equation (4), The value of the uniform intensity portion of the laser light Oo is set to E ₀ = 0.687.


Note that, based on this method, the desired intensity distribution of the shaped outgoing laser light can be not only a specified function but also an arbitrary intensity distribution.

Returning to the flowchart of FIG. 2, next, in the incident-side aspherical lens 11, the intensity distribution of the measured incident laser light Oi is divided at an arbitrary interval (width) in the distribution direction to obtain a plurality of incident light division regions ( (Incident light splitting step) (S03). For example, as shown in FIG. 5, is divided into substantially equal intervals in seven incident light splitting areas A1~A7 the intensity distribution of the incident laser light Oi measured at intervals [Delta] r _1.

  Next, in the exit-side aspherical lens 12, an exit light split region obtained by splitting the intensity distribution of the exit laser light Oo at an arbitrary interval (width) in the distribution direction, and a plurality of incident lights according to a desired intensity distribution. By adjusting the intensity (height) of each of the divided areas A1 to A7 and adjusting the width and position in the distribution direction, the plurality of outgoing light divided areas B1 to B7 are obtained (outgoing light dividing step) (S04). Specifically, the plurality of outgoing light division regions B1 to B7 may be obtained as follows.

  For example, first, as shown in FIG. 6, the desired intensity distribution of the outgoing laser light Oo is divided into seven outgoing light divided regions B1 to B7. In the present embodiment, adjustment from the Gaussian distribution to the super Gaussian distribution is assumed in advance, and the interval between the outgoing light division regions B4 located at the center is the largest, and the interval between the outgoing light division regions is desired to be smaller toward the outer side. Split the intensity distribution.

  Next, for example, as shown in FIG. 7, the incident light splitting regions A1 to A7 and the outgoing light splitting regions B1 to B7 are made to correspond to each other one by one, and the energy corresponding to the energy of the incident light splitting regions A1 to A7 is output. The width and position of each of the outgoing light splitting regions B1 to B7 are adjusted according to the increase or decrease in intensity (height) so that the energy of the splitting light splitting regions B1 to B7 becomes equal.

Returning to the flowchart of FIG. 2, the positions of the distribution directions of the incident light split areas A1 to A7 in the incident side aspheric lens 11 and the distribution directions of the corresponding output light split areas B1 to B7 in the output side aspheric lens 12. The optical path is specified from the position (optical path specifying step) (S05). For example, as shown in FIG. 8, the radius r ₁ coordinate direction of the incident light splitting areas A1~A7 the entrance-side aspherical lens 11, the radius of the corresponding emitted light divided regions B1~B7 at the exit side aspherical lens 12 by connecting the r ₂ direction of coordinates, determine the optical path P1~P8 of aspherical 11a on the entrance side aspherical lens 11 to the aspheric surface 12a of the exit-side aspheric lens 12.

  Next, the aspherical shapes of the pair of aspherical lenses 11 and 12 are obtained from the obtained optical paths P1 to P8 (shape determining step) (S06). Specifically, the aspheric shapes of the pair of aspheric lenses 11 and 12 may be obtained as follows.

In FIG. 9, for easy understanding, the incident laser light Oi is incident perpendicular to the plane 11 b of the incident-side aspherical lens 11, and the outgoing laser light Oo is incident on the plane 12 b of the outgoing-side aspherical lens 12. And emit vertically. Further, the m-th coordinate on the aspherical surface 11a of the incident-side aspherical lens 11 is r _1m , the m-th coordinate on the aspherical surface 12a of the corresponding exit-side aspherical lens 12 is r _2m , and these coordinates r Let P _m be the optical path connecting _{1 m} and the coordinates r _{2 m} . Further, the incident angle of the incident laser light Oi for aspheric 11a of coordinates r _{1 m} of the entrance-side aspherical lens 11 and theta _1, its angle of refraction, i.e., the outgoing angle of the light path P _m for the aspheric 11a theta _{1 '} To do. Similarly, the incidence angle of the light path P _m and theta _{2 'to} non-spherical 12a of the coordinate r _2m of the exit-side aspheric lens 12, the refraction angle, i.e., the emission angle of the emitted laser light Oo for aspheric 12a theta ₂ And The angle formed by the optical path P _m with respect to the main axes X ₁ and X ₂ is θ (the main axis X ₁ is a straight line perpendicular to the incident side plane 11b of the incident side aspherical lens 11, and the main axis X ₂ is is a straight line perpendicular to the exit side plane 12b of the exit-side aspheric lens 12. Further, it is parallel to the main axis X ₁ and the main shaft X _2.). Further, the refractive index of the incident-side aspherical lens 11 and the exit-side aspherical lens 12 is n, and the distance between the point 11c where the aspherical surface 11a intersects the optical axis X and the point 12c where the aspherical surface 12a intersects the optical axis X, That is, let L be the distance between the center position of the aspheric surface 11a (position of coordinates r ₁ = 0) and the center position of the aspheric surface 12a (position of coordinates r ₂ = 0).

For example, first, an angle θ formed by the optical path P _m with respect to the principal axes X ₁ and X ₂ is expressed as the following equation (5).

Further, the following equation (6) is established from Snell's law, and from this, the incident angle θ ₁ of the incident laser beam with respect to the aspheric surface 11a of the incident-side aspheric lens 11 is obtained as the following equation (7).

Here, the vicinity of the coordinate r _{1 m} of the incident-side aspherical lens 11 in FIG. 9 is enlarged and shown in FIG. In FIG. 10, the m−1th coordinate adjacent to the mth coordinate r _1m on the aspherical surface 11 a of the incident-side aspherical lens 11 is assumed to be r _1m−1 . Then, as shown in FIG. 10, the height difference ΔZ ₁ of the aspherical surface 11a between the coordinate r _1m and the adjacent coordinate r _1m−1 in the incident-side aspherical lens 11 is expressed by the following equation (8). Is done.

Accordingly, the height difference Z _1m of the aspherical surface 11a between the coordinate r _1m and the center position (coordinate r ₁ = 0) in the incident-side aspherical lens 11 is obtained as in the following equation (9).

  By performing these operations for all coordinates, that is, all incident light splitting regions A1 to A7 and optical paths P1 to P8, an incident-side aspherical lens for shaping the intensity distribution of the incident laser light into a desired intensity distribution. The shape of 11 aspherical surfaces 11a is obtained as shown in FIG.

Returning to FIG. 9, similarly, the emission angle θ ₂ of the emitted laser beam with respect to the aspheric surface 12 a of the emission side aspherical lens 12 is obtained by the following equation (10) from Snell's law.

Here, the vicinity of the coordinate r _2m of the emission side aspherical lens 12 in FIG. 9 is enlarged and shown in FIG. In FIG. 12, the m−1th coordinate adjacent to the mth coordinate r _2m on the aspheric surface 12 a of the emission side aspherical lens 12 is r _2m−1 . Then, as shown in FIG. 12, the height difference ΔZ ₂ of the aspheric surface 12a between the coordinate r _2m and the adjacent coordinate r _2m−1 in the exit-side aspheric lens 12 is expressed by the following equation (11). Is done.

Accordingly, the height difference Z _2m of the aspheric surface 12a between the coordinate r _2m and the center position (coordinate r ₂ = 0) in the emission side aspheric lens 12 is obtained as in the following equation (12).

  By performing these operations on all coordinates, that is, all the outgoing light splitting regions B1 to B7 and the optical paths P1 to P8, the phase of the laser light shaped into a desired intensity distribution by the incident-side aspherical lens 11 is aligned. The shape of the aspherical surface 12a of the outgoing side aspherical lens 12 for generating outgoing laser light changed to parallel light is obtained as shown in FIG.

  Returning to the flowchart of FIG. 2, next, the aspherical surface 11a of the incident-side aspherical lens 11 is molded based on the shape shown in FIG.11, and the aspherical surface 12a of the outgoing-side aspherical lens 12 based on the shape shown in FIG.13. Is molded (molding step) (S07).

Thus, according to the design method and the manufacturing method of the laser light shaping optical component of the first embodiment, the intensity distribution of the incident laser light Oi is actually measured, and the pair of aspherical lenses 11 are based on the actually measured intensity distribution. , 12 are designed. Further, a plurality of incident light split regions A1 to A7 obtained by dividing the actually measured intensity distribution of the incident laser light Oi are obtained, and the plurality of incident light split regions A1 to A7 are respectively determined according to a desired intensity distribution of the emitted laser light Oo. A plurality of outgoing light splitting regions B1 to B7 in which the intensity (height) is adjusted and the width and position in the distribution direction are adjusted, and the positions of the incident light splitting regions A1 to A7 in the incident-side aspherical lens 11 are determined. The optical paths P1 to P8 are specified from the positions of the corresponding plurality of outgoing light splitting regions B1 to B7 in the outgoing aspherical lens 12, and the shapes of the pair of aspherical lenses 11 and 12 are determined based on these optical paths P1 to P8. design. Therefore, it is possible to obtain an optical component for laser beam shaping that can shape the intensity distribution of the laser beam into an arbitrary intensity distribution with higher accuracy.
[Second Embodiment]

  In the first embodiment, the homogenizer design method and manufacturing method for changing parallel light into parallel light have been exemplified. However, the design method and manufacturing method of the present invention uses non-parallel light (incident laser light having a spread angle). The present invention can also be applied to a homogenizer design method and manufacturing method that change to non-parallel light (emitted laser light having a spread angle). Thus, when designing a homogenizer for incident laser light having a divergence angle, in addition to the intensity distribution of the incident laser light, the divergence angle of the incident laser light is measured and based on the actually measured intensity distribution and divergence angle. Thus, the shape of the aspheric lens may be obtained. Further, when designing a homogenizer for outgoing laser light having a divergence angle, in addition to the desired intensity distribution of the outgoing laser light, a desired divergence angle of the outgoing laser light is set, and the desired intensity distribution and What is necessary is just to obtain | require the shape of an aspherical lens based on a desired divergence angle. In the following, a homogenizer design method and manufacturing method according to the second embodiment of the present invention, in which a non-parallel light incident laser beam Oi is changed to a non-parallel light output laser beam Oo, is described. A method will be described.

  FIG. 14 is a flowchart showing a homogenizer design method and manufacturing method according to the second embodiment of the present invention. In the homogenizer design method and manufacturing method of the second embodiment, step S01 (incident light measurement process), step S02, and step S06 in the homogenizer design method and manufacturing method of the first embodiment shown in FIG. Instead of the process of (shape determination process), the process is different from the first embodiment in that the processes of step S11 (incident light measurement process), step S12, and step S16 (shape determination process) are performed.

  In step S11, the intensity distribution of the incident laser beam is measured as in step S01 described above. In step S11, the spread angle of the incident laser beam is measured. In step S12, as in step S02 described above, a desired intensity distribution of the emitted laser light is set. In step S12, a desired spread angle of the emitted laser light is set. In step S16, in addition to the obtained optical path, the aspheric shapes of the pair of aspheric lenses 11 and 12 are obtained based on the actually measured spread angle of the incident laser light and the desired spread angle of the set emission laser light. . Specifically, the aspheric shapes of the pair of aspheric lenses 11 and 12 may be obtained as follows.

15, in FIG. 9, incident laser light having a divergence angle is incident non-perpendicular to the plane 11 b of the incident-side aspherical lens 11, and outgoing laser light having a divergence angle is the plane of the emission-side aspherical lens 12. The difference is that the light is emitted non-perpendicular to 12b. Here, the incident laser light corresponding to the m-th optical path P _m , the incident angle of the incident laser light with respect to the plane 11b of the incident-side aspherical lens 11 is θ ₀ , and the refraction angle is θ ₀ ′. . Similarly, the laser light refracted by the aspheric surface 12a of the emission side aspherical lens 12 corresponding to the _mth optical path Pm, and the incident angle of the laser beam with respect to the flat surface 12b of the emission side aspherical lens 12 is θ _3. and 'a refractive angle, i.e., the emission angle of the emitted laser beam with respect to the plane 12b and theta _3. The other parameters in FIG. 15 are the same as the parameters in FIG. 9 described above. In FIG. 15, the vicinity of the coordinate r _{2m of} the emission side aspherical lens 12 is shown enlarged.

For example, first, the angle θ formed by the optical path P _m with respect to the main axes X ₁ and X ₂ is expressed as the above equation (5). Further, the following formulas (13) and (14) are established from Snell's law. From this, the incident laser beam is refracted incident laser light refracted by the plane 11b of the incident side aspheric lens 11, and is incident side aspheric. The incident angle θ ₁ of the refracted incident laser beam with respect to the aspherical surface 11 a of the lens 11 is obtained as in the following equation (15).

Here, the incident angle θ ₀ of the incident laser beam with respect to the flat surface 11 b of the incident-side aspherical lens 11 corresponds to the measured spread angle of the incident laser beam. Therefore, according to the above (15), the incident angle theta ₁ refracting incident laser light with respect to the aspherical surface 11a on the entrance side aspherical lens 11, and the angle theta formed by the optical path P _m to the main axis X _1, measured It is obtained from the spread angle θ ₀ of the incident laser light.

  In step S16, the equation (15) may be used instead of the equation (7) in step S06. Thereby, similarly to the above-described embodiment, the incident-side aspherical surface for shaping the intensity distribution of the incident laser light having the divergence angle into a desired intensity distribution based on the expressions (8) and (9). The shape of the aspherical surface 11a of the lens 11 can be obtained.

Similarly, from Snell's law, the refraction angle θ ₂ of the optical path P _m with respect to the aspheric surface 12a of the exit side aspheric lens 12 is obtained as in the following equation (16).

Here, the outgoing angle θ ₃ of the outgoing laser light with respect to the flat surface 12 b of the outgoing side aspherical lens 12 corresponds to a desired spread angle of the outgoing laser light. Therefore, according to the above equation (16), the refraction angle θ ₂ of the optical path P _m with respect to the aspheric surface 12 a of the exit-side aspheric lens 12 is equal to the angle θ formed by the optical path P _m with respect to the principal axis X ₂ , and the output laser light. and thus it obtained from the desired spread angle θ ₃ of.

  In step S16, the equation (16) may be used instead of the equation (10) in step S06. Thus, similarly to the above-described embodiment, the phase of the laser light shaped into a desired intensity distribution by the incident-side aspherical lens 11 is aligned based on the above formulas (11) and (12), and desired The shape of the aspherical surface 12a of the emitting side aspherical lens 12 for generating outgoing laser light having a divergence angle can be obtained.

If the incident laser light is parallel light, that is, if θ ₀ = θ ₀ ′ = 0 in the above equation (15), the above equation (7) is obtained, and if the emitted laser light is parallel light, that is, ( If θ ₃ = θ ₃ '= 0 in the equation (16), the above equation (10) is obtained.

  Thus, according to the laser beam shaping optical component design method and manufacturing method of the second embodiment, even if the incident laser beam is non-parallel light having a divergence angle, it also has an arbitrary divergence angle. Even when it is desired to obtain non-parallel emitted laser light, a laser light shaping optical component capable of shaping the intensity distribution of the laser light into an arbitrary intensity distribution with higher accuracy can be obtained.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in this embodiment, the intensity distribution of the incident laser light and the desired intensity distribution of the emitted laser light are concentric. Therefore, the aspherical shape can be calculated at high speed by performing the aspherical shape of the aspherical lens in one of the radial directions starting from the peak. On the other hand, when the intensity distribution of the incident laser light or the desired intensity distribution of the emitted laser light does not have symmetry, a two-dimensional operation is required.

  In this case, as shown in FIG. 16, the intensity distribution of the incident laser light Oi is divided into N × M pieces, and the intensity distribution of the emitted laser light Oo is divided into N × M pieces. Thereafter, in the same manner as in the outgoing light splitting process of the present embodiment described above, the incident light splitting area and the outgoing light splitting area are made to correspond one-to-one, and the energy of the incident light splitting area and the energy of the corresponding outgoing light splitting area are matched. And the width and position of each of the outgoing light split regions are adjusted according to the increase / decrease in intensity (height). In this case, it is preferable to perform the above adjustment starting from an arbitrary position where the intensity is 0, or the position of the center of gravity.

  In this case, as shown in FIG. 17 (shown in cross-sectional shape for the sake of simplicity), the shape correction is performed so that the obtained first-order component of the aspheric shape of the incident-side aspheric lens becomes zero. Is preferred. This is because the aspherical primary component indicates a spatial shift in the direction perpendicular to the optical axis at the position of the exit-side aspheric lens and does not affect the spatial intensity distribution. In addition, the lens processing time can be shortened by reducing the height difference of the aspherical lens.

  Based on the homogenizer design method and manufacturing method of the first embodiment of the present invention, the homogenizer 10 of the present example was fabricated and its characteristics were evaluated.

In this embodiment, CaF ₂ (n = 1.42) is used as the material of the pair of aspheric lenses 11 and 12 constituting the homogenizer 10, and the aspheric surfaces 11a and 11a at the center positions of the pair of aspheric lenses 11 and 12 are used. The distance of 12a was designed as L = 165 mm.
(Evaluation 1)

  First, the characteristics of only the incident side aspheric lens 11 were evaluated. In this evaluation, as shown in FIG. 18, the output laser light from the collimating lens 4 was changed by 90 degrees using the reflecting mirror 21 and made incident on the incident-side aspherical lens 11. Then, the spatial mode (intensity distribution) of the laser beam emitted from the incident side aspherical lens 11 was measured by the beam profiler 32 via the imaging lens system 31. Further, the spatial mode (intensity distribution) of the incident laser light to the incident-side aspherical lens 11 was also measured by the imaging lens system 31 and the beam profiler 32. These measurement results are shown in FIG.

  In the present embodiment, as described above, the laser light emitted from the laser light source 2 is shaped into a concentric Gaussian distribution by the spatial filter 3 and the collimating lens 4. Thereby, in the present Example, as above-mentioned, the homogenizer 10 was designed by the one-dimensional analysis (central rotation symmetrical intensity distribution).

  FIG. 19A shows the measurement result of the spatial mode (intensity distribution) of the incident laser light to the incident-side aspherical lens 11, and FIGS. 19B to 19R are diagrams from the incident-side aspherical lens 11. It is a measurement result of the spatial mode (intensity distribution) after the emitted laser light has propagated by 10 mm to 170 mm, respectively. Thus, according to the incident-side aspherical lens 11 of this embodiment, the intensity distribution of the laser beam can be shaped into a spatially uniform intensity distribution, that is, a super Gaussian distribution after propagation of about 165 mm, which is a lens interval design value. confirmed.

FIG. 20 shows a comparison result between the actually measured value and the design value of the intensity distribution after the laser beam emitted from the incident-side aspherical lens 11 has propagated 165 mm. FIG. 20 also shows actual measurement values of the intensity distribution of the incident laser beam applied to the incident-side aspherical lens 11. From this, according to the incident-side aspherical lens 11 of the present example, it was confirmed that the intensity distribution of the laser beam can be shaped almost as designed after propagation of 165 mm which is the lens interval design value.
(Evaluation 2)

  Next, the characteristics evaluation of the incident-side aspherical lens 11 and the emission-side aspherical lens 12, that is, the characteristics evaluation of the homogenizer 10 was performed. In this evaluation, as shown in FIG. 21, the output laser light from the collimating lens 4 was changed by 90 degrees using the reflecting mirror 21 and made incident on the homogenizer 10. Then, the optical path of the laser beam emitted from the homogenizer 10 was changed by 90 degrees using the reflecting mirror 22, and the spatial mode (intensity distribution) was measured by the beam profiler 32 via the imaging lens system 31. The measurement results are shown in FIG.

  FIG. 22A shows the measurement result of the spatial mode (intensity distribution) of the emitted laser light immediately after emission from the homogenizer 10 of this embodiment, and FIGS. 22B to 22F show the homogenizer 10 of this embodiment. It is the measurement result of the spatial mode (intensity distribution) after the laser beam emitted from each propagates 10 mm to 50 mm. From this, according to the homogenizer 10 of the present embodiment, the laser light having the intensity distribution shaped by the incident-side aspherical lens 11 is aligned in phase by the emission-side aspherical lens 12, and emitted as parallel light. It was confirmed that the intensity distribution can be maintained even after propagating 10 to 50 mm.

  DESCRIPTION OF SYMBOLS 1 ... Optical apparatus, 2 ... Laser light source, 3 ... Spatial filter, 4 ... Collimating lens, 10 ... Homogenizer (laser light shaping optical component), 11 ... Incident side aspherical lens in a pair of aspherical lenses, 11a ... Aspherical surface , 11b... Plane, 12... Exit side aspheric lens in a pair of aspheric lenses, 12a... Aspheric surface, 12b. ... incident light splitting region, B1-B7 ... outgoing light splitting region, Oi ... incident laser light, Oo ... outgoing laser light, P1-P8 ... optical path, X ... optical axis.

Claims (10)

In a design method of an optical component for laser light shaping, which includes a pair of aspheric lenses and generates outgoing laser light in which the intensity distribution of incident laser light is shaped into a desired intensity distribution,
An incident light measurement step of measuring the intensity distribution of the incident laser light;
In the incident side aspherical lens of the pair of aspherical lenses, an incident light dividing step of dividing a measured intensity distribution of the incident laser light in a distribution direction to obtain a plurality of incident light dividing regions;
In the emission side aspherical lens of the pair of aspherical lenses, there are a plurality of emission light division regions obtained by dividing the intensity distribution of the emission laser light in a distribution direction, and the plurality of emission light splitting regions according to the desired intensity distribution An outgoing light splitting step for obtaining the plurality of outgoing light splitting regions by adjusting the height of each of the incident light splitting regions and adjusting the width and position in the distribution direction;
An optical path specifying step of specifying an optical path from a position in the distribution direction of the plurality of incident light split regions in the incident side aspheric lens and a position in the distribution direction of the corresponding plurality of output light split regions in the output side aspheric lens When,
A shape determining step for determining the shape of the pair of aspheric lenses from the optical path;
A method for designing an optical component for laser beam shaping. In the outgoing light splitting step, the width and position of the plurality of incident light splitting regions in the distribution direction so that the energy of the plurality of incident light splitting regions is equal to the energy of the corresponding outgoing light splitting regions, respectively. To determine the plurality of outgoing light split regions,
The method for designing a laser beam shaping optical component according to claim 1. In the shape determination step,
The shape of the incident side aspheric lens is determined from the optical path,
Obtaining the shape of the exit-side aspherical lens from the optical path and obtaining the exit laser light to be parallel light by aligning the phase of the exit laser light,
The method for designing a laser beam shaping optical component according to claim 1. In the shape determination step, in each of the plurality of incident light division regions,
From the angle formed by the optical path with respect to the principal axis perpendicular to the incident-side plane of the incident-side aspheric lens, the incident angle of the incident laser light with respect to the aspheric surface on the exit side of the incident-side aspheric lens is determined,
From the incident angle of the incident laser light with respect to the aspheric surface of the incident side aspheric lens, the height difference of the aspheric surface of the incident side aspheric lens is obtained.
The method for designing a laser beam shaping optical component according to claim 1 or 3. In the shape determination step, in each of the plurality of outgoing light division regions,
From the angle formed by the optical path with respect to the principal axis perpendicular to the plane on the exit side of the exit side aspheric lens, the exit angle of the exit laser beam with respect to the aspheric surface on the entrance side of the exit side aspheric lens is determined.
From the exit angle of the exit laser light with respect to the aspheric surface of the exit side aspheric lens, the height difference of the aspheric surface of the exit side aspheric lens is obtained.
The method for designing a laser beam shaping optical component according to claim 1 or 3. In the incident light measurement step, further, the spread angle of the incident laser light is measured,
In the shape determination step, the shape of the incident-side aspheric lens is obtained from the optical path and the spread angle of the measured incident laser light.
The method for designing a laser beam shaping optical component according to claim 1. In the shape determination step, the shape of the exit-side aspheric lens is obtained from a desired spread angle of the optical path and the exit laser beam.
The method for designing a laser beam shaping optical component according to claim 1. In the shape determination step, in each of the plurality of incident light division regions,
From the angle formed by the optical path with respect to the principal axis perpendicular to the plane on the incident side of the incident side aspherical lens and the spread angle of the measured incident laser light, the incident laser beam is projected on the plane of the incident side aspherical lens. Is the refracted incident laser light refracted, and finds the incident angle of the refracted incident laser light with respect to the exit-side aspheric surface of the incident-side aspheric lens,
From the incident angle of the refractive incident laser light with respect to the aspherical surface of the incident-side aspherical lens, the height difference of the aspherical surface of the incident-side aspherical lens is obtained.
The design method of the optical component for laser beam shaping of Claim 6. In the shape determination step, in each of the plurality of outgoing light division regions,
From the angle formed by the optical path with respect to the principal axis perpendicular to the plane of the exit side of the exit side aspheric lens and the desired spread angle of the exit laser beam, the exit side aspheric lens is in contact with the entrance side aspheric surface. Find the refraction angle of the optical path,
From the refraction angle of the optical path with respect to the aspheric surface of the exit side aspheric lens, obtain the height difference of the aspheric surface of the exit side aspheric lens,
The design method of the optical component for laser beam shaping of Claim 7. In a method for manufacturing an optical component for laser beam shaping, which includes a pair of aspheric lenses and generates emitted laser beam in which the intensity distribution of incident laser beam is shaped into a desired intensity distribution,
An incident light measurement step of measuring the intensity distribution of the incident laser light;
In the incident side aspherical lens of the pair of aspherical lenses, an incident light dividing step of dividing a measured intensity distribution of the incident laser light in a distribution direction to obtain a plurality of incident light dividing regions;
In the emission side aspherical lens of the pair of aspherical lenses, there are a plurality of emission light division regions obtained by dividing the intensity distribution of the emission laser light in a distribution direction, and the plurality of emission light splitting regions according to the desired intensity distribution An outgoing light splitting step for obtaining the plurality of outgoing light splitting regions by adjusting the height of each of the incident light splitting regions and adjusting the width and position in the distribution direction;
An optical path specifying step of specifying an optical path from a position in the distribution direction of the plurality of incident light split regions in the incident side aspheric lens and a position in the distribution direction of the corresponding plurality of output light split regions in the output side aspheric lens When,
A shape determining step for determining the shape of the pair of aspheric lenses from the optical path;
A molding step of molding the pair of aspheric lenses based on the obtained shape;
A method for manufacturing an optical component for laser beam shaping, comprising: