JP2016218313A - Image formation optical system and optical adjustment method of image formation optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation optical system and optical axis adjustment method in which even in image formation optical systems having optical components with an allowance such as a refractive index, deviations of an optical axis and position and so forth combined, in an entire system, an optical adjustment of a specific portion can be easily made as discriminating the image formation optical system from other lenses.SOLUTION: A surface evaluation device is configured to irradiate an image formation optical system composed of a first lens, a second lens, an N-th lens, and a compensator with light of a wavelength other than a use wavelength from a light source, and a detector is configured to detect the light that is reflected by a coating after passing through the first lens, second lens and compensator, and again passes through the compensator, second lens, and first lens by means of a double path. The compensator having the coating 2a coated is moved back and forth, and thus, an optical path length varies, and a wavefront varies. Therefor, the compensator is adjusted so that a result of a change in wavefront is a wavefront as optically designed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical system having high imaging performance, such as a photographic lens, and an optical adjustment method for the imaging optical system.

  In general, the imaging optical system is designed to geometrically adjust the position of the optical component by fitting the optical component such as a lens or a mirror into a lens barrel having a manufacturing accuracy of the order of 10 μm. The optical axis shift due to the shift is suppressed and desired optical performance is realized. In addition, when the position accuracy of the optical component is stricter than the manufacturing accuracy of the optical component and the lens barrel, and it is difficult only by geometric adjustment, the position that can be adjusted to the optical component (hereinafter referred to as a compensator). ): Compensation mechanism for minimizing degradation of optical performance due to tolerances)), and optically adjust the position of the optical component by measuring and evaluating the optical performance (hereinafter referred to as optical adjustment) Yes.

  When the desired optical performance is very high, MTF and wavefront aberration also have high error sensitivity with respect to the design value, and the positional accuracy of the optical component is required to be on the order of μm or less. Further, the optical system becomes complicated by increasing the number of lens components or by providing a plurality of compensators. In addition, the lens group composed of a plurality of lenses or compensators has a synergistic effect of the tolerance of each lens even when the tolerances of the shape, refractive index, optical axis deviation and positional deviation of each optical component are small, Since the optical performance is affected, it is necessary to optimize the optical adjustment in the entire system (for example, see Patent Document 1).

  Patent Document 1 discloses a light source for irradiating a light beam to an optical system having a plurality of lenses, and a light-shielding unit provided between the light source and the optical system for changing the irradiation area of the light beam to the optical system. An optical system assembly provided with a detection means for detecting the back focus of the optical system by detecting the center of gravity position of the intensity distribution of the light passing through the optical system, provided at the design nominal position of the back focus of the optical system In the adjustment device, an assembly adjustment device and an assembly adjustment method are disclosed in which optical performance is measured and evaluated for an optical system having a plurality of lenses, and an interval between the lenses is adjusted so as to obtain a design nominal value. .

JP-A-11-109199

  However, in the method of Patent Document 1, when the number of lenses or compensators constituting the optical system increases, the optical performance of each lens or each compensator is affected by the tolerance of each of the front or rear stage lenses or the compensator. Therefore, it becomes difficult to perform optical adjustment in the entire system to obtain a desired optical performance.

  The imaging optical system according to the present invention includes a lens group including at least one lens having a coating on at least one surface that transmits a desired use wavelength and reflects outside the use wavelength. An image optical system, a light source that generates light outside the use wavelength, and a detector that detects light outside the use wavelength, and the light from the light source detected by the detector is detected by the imaging optical system. And a wavefront measuring device that evaluates the wavefront of the imaging optical system based on the reflected light.

  The imaging optical system according to the present invention includes a lens group including at least one lens having a coating that transmits a desired use wavelength and reflects a light other than the use wavelength on at least one surface. The coating needs to be applied to the lens that needs to be optically adjusted. When coating a plurality of lenses, coatings that reflect different wavelength bands from bands other than the used wavelength are used.

  The optical adjustment of the imaging optical system includes a light source that generates light other than the used wavelength and a detector that can detect light other than the used wavelength, and can evaluate the wavefront of the imaging optical system. Optical adjustment is performed by a wavefront evaluation apparatus.

  In the optical adjustment, light having a wavelength other than the used wavelength is irradiated to the coated lens, and the wavefront obtained by double-passing the lens group is evaluated. The coated lens is adjusted so that the result is a wavefront according to the optical design. When there are a plurality of coated lenses, the wavelength band of light used for optical adjustment uses a different wavelength band reflected by each coating.

  In this way, each lens with a coating that reflects a different wavelength band from a band other than the used wavelength is subjected to wavefront evaluation in a different wavelength band, so that optical adjustment of a specific part is performed in distinction from other lenses. Can do. As a result, it is possible to distinguish the contribution of each lens to the optical performance, so that even when there are many components, optical adjustment in the entire system can be easily performed.

It is a figure which shows roughly the imaging optical system by Embodiment 1 of this invention, and its optical adjustment method. It is a figure which shows roughly the imaging optical system by Embodiment 2 of this invention, and its optical adjustment method. It is a figure which shows schematically the imaging optical system by Embodiment 3 of this invention, and its optical adjustment method. It is a figure which shows roughly the imaging optical system by Embodiment 4 of this invention, and its optical adjustment method.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or equivalent components are denoted by the same reference numerals and description thereof is omitted.

Embodiment 1 FIG.
FIG. 1 is a diagram schematically showing an imaging optical system and an optical adjustment method thereof according to Embodiment 1 of the present invention.

The imaging optical system 10 is an optical system that forms an image of a desired use wavelength from a target, for example, near-infrared light in a 1 μm band on an arbitrary light receiving surface, and includes a first lens 31, a second lens 32, and an Nth lens. The lens 30 and the compensator 40 are included.
The first lens 31, the second lens 32, and the Nth lens 30 are synthetic quartz that transmits light in the 200-2000 nm band or a BK7 lens that transmits light in the 350-2000 nm band. The compensator 40 is configured such that a plurality of synthetic quartz or BK7 lenses are fixed by a lens barrel and the positions thereof can be adjusted together. Further, a coating 2a is applied to one surface of one lens of the compensator 40. The coating 2a is a dielectric multilayer film that transmits near-infrared light in the 1 μm band and reflects visible light other than the used wavelength, for example, 632.8 nm.

  The wavefront measuring device 50 is composed of a light source 51 and a detector 52, and irradiates the object to be measured with 632.8 nm visible light, and measures the state of the wavefront obtained by reflecting the irradiated light from the object to be measured. And an interferometer such as a Fizeau interferometer or a Shack-Hartmann sensor or a wavefront sensor. For example, the light source 51 is a He—Ne laser oscillator that generates 632.8 nm light, and the detector 52 is a CCD image sensor capable of detecting 632.8 nm light. The light source 51 and the detector 52 may be separated.

Next, an optical adjustment method for the imaging optical system will be described.
The imaging optical system 10 is irradiated with light having a wavelength band of 632.8 nm, which is a wavelength other than the used wavelength, from the light source 51 by the wavefront evaluation apparatus 50, and after passing through the first lens 31, the second lens 32, and the compensator 40, The detector 52 detects the light reflected by the coating 2a and transmitted again through the second lens 32 and the first lens 31 in the compensator 40 through the double path. The wavefront evaluation apparatus 50 can evaluate the disturbance of the wavefront by a change in fringes due to interference with the reference wavefront. By moving the compensator 40 to which the coating 2a has been applied back and forth, the optical path length changes and the wavefront changes, so that the result is adjusted so as to be a wavefront according to the optical design. In the optical design, the wavefront is calculated for 632.8nm light. Since the wavefront is adjusted to the optical design, it is possible to form an image close to the desired optical performance. Note that the compensator may adjust the wavefront in a plane or by changing the mounting angle. Moreover, the design method of the optical design performed when evaluating a wavefront is not ask | required. Further, after the optical adjustment, the entire imaging optical system 10 is fixed by a lens barrel or the like.

As a result, the contribution to the optical performance by the compensator 40 can be distinguished from other lenses, so that even when there are many components, optical adjustment of a specific location can be easily performed in the entire system.
Here, when the optical adjustment is completed as a single compensator, the surface to be coated may be only one surface of the lens constituting the compensator, and the coating can be reduced. Furthermore, since the number of lenses for adjusting the optical axis is reduced, the operation becomes easy. Also, the coating needs to be applied to lenses that need to be optically adjusted. The surface to be coated is preferably a back surface in which the light irradiation side is the front surface and the opposite is the back surface, and the double-pass path includes the optical path in the target lens.

Embodiment 2. FIG.
FIG. 2 is a diagram schematically showing an imaging optical system and an optical adjustment method thereof according to Embodiment 2 of the present invention.

  The imaging optical system 10 is an optical system that forms an image of a desired use wavelength from a target, for example, mid-infrared light in a 3-5 μm band on an arbitrary light receiving surface, and includes a first lens 31, a second lens 32, The lens includes a third lens 33, a fourth lens 34, and an Nth lens 30. The first lens 31, the second lens 32, the third lens 33, the fourth lens 34, and the Nth lens 30 are made of Si that transmits light in the 1.2-6 μm band, ZnSe that transmits light in the 0.7-10 μm band, or 2- This is a Ge lens that passes light in the 20 μm band. One surface of the first lens 31 and the third lens 33 is coated with a coating 2a, and one surface of the second lens 32 and the fourth lens 34 is coated with a coating 2b. The coating 2a is a dielectric multilayer film that transmits mid-infrared light in the 3-5 μm band and reflects visible light other than the wavelength used, for example, 532 nm. The coating 2b is a dielectric multilayer film that transmits mid-infrared light in the 3-5 μm band and reflects near-infrared light of, for example, 1064 nm other than the wavelength used.

  The wavefront measuring apparatus 50 includes a light source 51 and a detector 52, and irradiates the object to be measured with 632.8 nm or 1064 nm light, and measures the state of the wavefront obtained by reflecting the irradiated light from the object to be measured. And an interferometer such as a Fizeau interferometer or a Shack-Hartmann sensor or a wavefront sensor. The light source 51 is a Nd: YAG laser oscillator that generates near-infrared light of 1064 nm and a wavelength-converted laser light source that generates visible light of 532 nm, which is a double wave thereof, and the detector 52 emits light of 532 nm and 1064 nm. This is a detectable CCD image sensor. The wavefront measuring device 53 includes a light source 54 and a detector 55, and has the same configuration as the wavefront measuring device 50.

Next, an optical adjustment method for the imaging optical system will be described.
The imaging optical system 10 is irradiated with light having a wavelength band of 532 nm from the irradiation surface (table) 61 by the wavefront evaluation apparatus 50, passes through the first lens 31, is reflected by the coating 2 a, and is again the first lens. The light passing through 31 through the double path is detected by the detector 52. The wavefront evaluation apparatus 50 can evaluate the disturbance of the wavefront by a change in fringes due to interference with the reference wavefront. By moving the first lens 31 coated with the coating 2a back and forth, the optical path length changes and the wavefront changes, so that the result is adjusted so as to be a wavefront according to the optical design. In the optical design, the wavefront is calculated according to the light of 532 nm. Since the wavefront is adjusted to the optical design, it is possible to form an image close to the desired optical performance. The lens may be adjusted in the wavefront by changing the mounting angle within a plane. Moreover, the design method of the optical design performed when evaluating a wavefront is not ask | required.

  Subsequently, the wavefront evaluation apparatus 50 irradiates light having a wavelength band of 1064 nm from the irradiation surface (table) 61, passes through the first lens 31, the coating 2a, and the second lens 32, and then is reflected by the coating 2b. The second lens 32 is adjusted by performing the same evaluation by detecting the light transmitted through the double lens 32, the coating 2a, and the first lens 31 by the double path by the detector 52.

  According to the same procedure, the wavefront evaluation device 53 is used to irradiate light of a wavelength band of 532 nm from the irradiation surface (back) of the third lens 33 and of the fourth lens 34 of light of a wavelength band of 1064 nm. Perform wavefront evaluation and adjustment. The order of lens adjustment is not limited. The wavefront evaluation apparatus may be changed when adjusting each wavelength band. Further, after the optical adjustment, the entire imaging optical system 10 is fixed by a lens barrel or the like.

  As a result, each contribution to the optical performance by the first lens 31 to the fourth lens 34 can be distinguished from other lenses, so even if there are many components, optical adjustment of a specific location in the entire system Can be done easily. Further, by evaluating the same lens from both sides of the irradiation surface (front) 61 and the irradiation surface (back) 62, it is possible to perform adjustment so as to obtain an optimum value. In addition, since the type of coating used is about half of the number of lenses for optical axis adjustment, the type of coating and the type of light source of the wavefront measuring apparatus can be reduced.

  Here, the coating needs to be applied to the lens that needs to be optically adjusted. The surface to be coated is preferably a back surface in which the light irradiation side is the front surface and the opposite is the back surface, and the double-pass path includes the optical path in the target lens. For the same reason, in the first lens 31 and the third lens 33 having the same coating, for example, the first lens 31 and the third lens 33 having the coating 2a, the first lens 31 is connected to the third lens from the irradiation surface (table) 61 In the case of performing the evaluation and adjustment by irradiating light from the irradiation surface (back) 62, it is desirable that the lens 33 to be evaluated be disposed on each evaluation surface side. For example, the irradiation surface (front) 61, the first lens 31, and the third lens 33 irradiation surface (back) 62 are arranged in this order from the left side in the drawing. A lens with a coating that reflects different wavelength bands may be inserted between them.

Embodiment 3
FIG. 3 is a diagram schematically showing an imaging optical system and an optical adjustment method thereof according to Embodiment 3 of the present invention.

  The imaging optical system 10 is an optical system that forms an image of a desired use wavelength from a target, for example, mid-infrared light in a 3-5 μm band on an arbitrary light receiving surface, and includes a first lens 31, a second lens 32, The lens includes a third lens 33, a fourth lens 34, and an Nth lens 30. The first lens 31, the second lens 32, the third lens 33, the fourth lens 34, and the Nth lens 30 are made of Si that transmits light in the 1.2-6 μm band, ZnSe that transmits light in the 0.7-10 μm band, or 2- This is a Ge lens that passes light in the 20 μm band. In addition, each lens surface is coated, and each coating transmits a 3-5μm band mid-infrared light and reflects a different wavelength band within the 1260-1608nm band. It is.

  The wavefront measuring apparatus 50 includes a light source 51 and a detector 52, and irradiates the object to be measured with light in a band of 1260-1608 nm, and measures the state of the wavefront obtained by reflecting the irradiated light from the object to be measured. And an interferometer or wavefront sensor such as a Fizeau interferometer or Shack-Hartmann sensor. The light source 51 is a wavelength tunable laser light source capable of changing the wavelength band at intervals within the 1260-1608 nm band, and the detector 52 is a CCD image sensor capable of detecting light in the 1260-1608 nm band. is there. The wavefront measuring device 53 includes a light source 54 and a detector 55, and has the same configuration as the wavefront measuring device 50.

  Next, an optical adjustment method for the imaging optical system will be described. The imaging optical system 10 is irradiated by the wavefront evaluation device 50 from the irradiation surface (table) 61 with a portion of the light reflected by the coating 2b from the band of 1260-1608 nm. , The light reflected by the coating 2b and transmitted again through the first lens 31 and the coating 2a in a double pass is detected by the detector 52. The wavefront evaluation apparatus 50 can evaluate the disturbance of the wavefront by a change in fringes due to interference with the reference wavefront. By moving the first lens 31 provided with the coating 2b back and forth, the optical path length changes and the wavefront changes, so that the result is adjusted to be a wavefront as designed in the optical design. In the optical design, the wavefront is calculated according to the light of a partial band included in the irradiated 1260-1608 nm band. Since the wavefront is adjusted to the optical design, it is possible to form an image close to the desired optical performance. The lens may be adjusted in the plane or by changing the mounting angle. . The optical design means may be any design method as long as it can be comparatively evaluated with the wavefront.

  Subsequently, a part of the light reflected by the coating 2d is irradiated from the irradiation surface (table) 61 from the band of 1260-1608 nm to pass through the coating 2a, the first lens 31, the coating 2b, the coating 2c, and the second lens 32. After passing, the same evaluation is performed by detecting the light reflected by the coating 2d and transmitted again through the second lens 32, the coating 2c, the coating 2b, the first lens 31, and the coating 2a by the double path. 2 The lens 32 is adjusted.

  According to the same procedure, the third lens 33, the fourth lens 34, and the Nth lens are irradiated by sequentially irradiating the light reflected by the coating f, the coating h, and the coating j from the irradiation surface (table) 61 to the band of 1260-1608 nm. Wavefront evaluation and adjustment of the lens 30 are performed. Similarly, all the lenses can be adjusted by sequentially irradiating light reflected from coating a, coating c, coating e, coating g and coating i from the irradiation surface (back) 62 to 1260-1608 nm. it can. The order of lens adjustment is not limited. The wavefront evaluation apparatus may be changed when adjusting each wavelength band. Further, after the optical adjustment, the entire imaging optical system 10 is fixed by a lens barrel or the like.

  As a result, each contribution to the optical performance by the first lens 31 to the Nth lens 30 can be distinguished from other lenses. Therefore, even when there are many components, the optical adjustment of a specific location in the entire system is possible. Can be done easily. Further, by evaluating the same lens from both sides of the irradiation surface (front) 61 and the irradiation surface (back) 62, it is possible to perform adjustment so as to obtain an optimum value. Further, when only one of the evaluation and adjustment can be performed, the optical adjustment can be performed from either side. When optical adjustment is performed only from one irradiation surface, the coating may be only on one side. The surface to be coated is preferably a back surface in which the light irradiation side is the front surface and the opposite is the back surface, and the optical path in the target lens is included in the double path.

Embodiment 4 FIG.
FIG. 4 is a diagram schematically showing an imaging optical system and an optical adjustment method thereof according to Embodiment 4 of the present invention.

  The imaging optical system 10 is an optical system that forms an image of visible light in a desired use wavelength from a target, for example, a 0.3-0.7 μm band on an arbitrary light receiving surface, and includes a first lens 31, a second lens 32, and a second lens. The lens includes a third lens 33, a fourth lens 34, and an Nth lens 30. The first lens 31, the second lens 32, the third lens 33, the fourth lens 34, and the Nth lens 30 are synthetic quartz lenses that transmit light in the 200-2000 nm band. Each lens surface is coated, and each coating is a dielectric multilayer film that transmits visible light in the 0.3-0.7μm band and reflects light in different wavelength bands within the 1260-1608nm band. is there.

  The wavefront measuring apparatus 50 includes a light source 51 and a detector 52, and irradiates the object to be measured with light in a band of 1260-1608 nm, and measures the state of the wavefront obtained by reflecting the irradiated light from the object to be measured. And an interferometer or wavefront sensor such as a Fizeau interferometer or Shack-Hartmann sensor. The light source 51 is a tunable laser light source or a semiconductor laser light source capable of changing the wavelength band at intervals within the 1260-1608 nm band, and the detector 52 can detect light in the 1260-1608 nm band. This is a CCD sensor. The wavefront measuring device 53 includes a light source 54 and a detector 55, and has the same configuration as the wavefront measuring device 50.

Next, an optical adjustment method for the imaging optical system will be described.
The imaging optical system 10 is irradiated by the wavefront evaluation device 50 from the irradiation surface (table) 61 with a portion of the light reflected by the coating 2b from the band of 1260-1608 nm. , The light reflected by the coating 2b and transmitted again through the first lens 31 and the coating 2a in a double pass is detected by the detector 52. The wavefront evaluation apparatus 50 can evaluate the disturbance of the wavefront by a change in fringes due to interference with the reference wavefront. By moving the first lens 31 provided with the coating 2b back and forth, the optical path length changes and the wavefront changes, so that the result is adjusted to be a wavefront as designed in the optical design. In the optical design, the wavefront is calculated according to the light of a partial band included in the irradiated 1260-1608 nm band. Since the wavefront is as designed in the optical design, it is possible to form an image close to the desired optical performance. The lens may be adjusted in the wavefront by changing the mounting angle within a plane. Any optical design means can be used as long as it can be compared with the wavefront.

  Subsequently, a part of the light reflected by the coating 2c from the 260-1608 nm band is irradiated from the irradiation surface (table) 61, and the inside of the coating 2a, the first lens 31, the coating 2b, the coating 2b, and the second lens 32 is irradiated. After passing, the second evaluation is performed by detecting the light reflected by the coating 2c and transmitted again through the second lens 32, the coating 2b, the first lens 31, and the coating 2a by the double path by the detector 52. The lens 32 is adjusted.

  According to the same procedure, the third lens 33, the fourth lens 34, the Nth lens are irradiated by sequentially irradiating the light reflected from the coating d, the coating e, and the coating f from the irradiation surface (table) 61 to the band of 1260-1608 nm. Wavefront evaluation and adjustment of the lens 30 are performed. Similarly, all the lenses can be adjusted by sequentially irradiating light of coating a, coating b, coating c, coating d, and coating e from the irradiation surface (back) 62 to a band of 1260-1608 nm. The order of lens adjustment is not limited. The wavefront evaluation apparatus may be changed when adjusting each wavelength band. Further, after the optical adjustment, the entire imaging optical system 10 is fixed by a lens barrel or the like.

  As a result, each contribution to the optical performance by the first lens 31 to the Nth lens 30 can be distinguished from other lenses. Therefore, even when there are many components, the optical adjustment of a specific location in the entire system is possible. Can be done easily. Further, by evaluating the same lens from both sides of the irradiation surface (front) 61 and the irradiation surface (back) 62, it is possible to perform adjustment so as to obtain an optimum value. Further, when only one of the evaluation and adjustment can be performed, the optical adjustment can be performed from either side.

  In Example 3, the number of types of coating is twice as large as the number of lenses, whereas the number of types of coating used is two in addition to the number of lenses that perform optical axis adjustment. It is possible to reduce the types and types of light sources of the wavefront measuring apparatus. The surface to be coated is preferably a back surface in which the light irradiation side is the front surface and the opposite is the back surface, and the double-pass path includes the optical path in the target lens. Furthermore, in order to reduce the types of coatings, each coating that reflects the same wavelength band is used for each surface facing between the lenses. Further, it is desirable that the coating applied to the lens surface closest to the irradiation surface (front) 61 and the irradiation surface (back) 62 is a coating that reflects different wavelength bands.

10 Imaging optical system, 2a coating (reflection wavelength band: a), 2b coating (reflection wavelength band: b), 2c coating (reflection wavelength band: c), 2d coating (reflection wavelength band: d), 2e coating (reflection) Wavelength band: e), 2f Coating (reflection wavelength band: f), 30 Nth lens, 31 1st lens, 32 2nd lens, 33 3rd lens, 34 4th lens, 40 compensator, 50 wavefront measuring device, 51 Light source, 52 detector, 53 wavefront measuring device, 54 light source, 55 detector, 61 irradiation surface (front), 62 irradiation surface (back)

Claims (8)

An imaging optical system comprising a plurality of lenses that transmit light of a first wavelength that is a working wavelength,
The plurality of lenses include at least one lens having a coating that reflects light having a second wavelength different from the used wavelength on at least one surface;
The imaging optical system characterized in that the lens provided with the coating that reflects the light of the second wavelength is movable for optical adjustment.   The optical adjustment is an adjustment to make the wavefront of the reflected light of the second wavelength light reflected by the lens coated with the coating reflecting the light of the second wavelength coincide with a desired wavefront. The imaging optical system according to claim 1.   The imaging optical system according to claim 1, wherein the lens provided with the coating that reflects the light having the second wavelength is one of lenses constituting a compensator. The plurality of lenses include at least one lens having a coating that reflects light of a third wavelength, which is different from the first wavelength and the second wavelength, on at least one surface;
The lens provided with the coating that reflects the light of the third wavelength is movable for optical adjustment,
The optical adjustment is an adjustment to make the wavefront of the reflected light of the third wavelength light reflected by the lens coated with the third wavelength light coincide with a desired wavefront. The imaging optical system according to any one of claims 1 to 3. Each lens surface of the plurality of lenses is provided with a coating that reflects light of different wavelengths,
The imaging optical system according to claim 1, wherein each lens is movable for optical adjustment. A coating that reflects light of the same wavelength is applied to the facing surfaces of adjacent lenses among the plurality of lenses,
The imaging optical system according to claim 1, wherein the wavelength to be reflected is different for each facing surface of an adjacent lens. An optical adjustment method for an imaging optical system comprising a plurality of lenses that transmit light of a first wavelength that is a working wavelength,
Irradiating light having a second wavelength different from the used wavelength from the incident side or the emission side of the coupling optical system,
Of the plurality of lenses, the wavefront of the reflected light of the second wavelength reflected by the second wavelength reflecting lens that has been coated in advance to reflect the light of the second wavelength is a desired wavefront. An optical adjustment method for an imaging optical system, wherein the position of the second wavelength reflection lens is adjusted. An optical adjustment method for an imaging optical system comprising a plurality of lenses that transmit light of a first wavelength that is a working wavelength,
Irradiate light having a second wavelength different from the use wavelength from the incident side of the coupling optical system,
Of the plurality of lenses, the wavefront of the reflected light of the second wavelength reflected by the second wavelength reflecting lens that has been coated in advance to reflect the light of the second wavelength is a desired wavefront. Adjusting the position of the second wavelength reflection lens,
Irradiating light of a third wavelength different from the first wavelength and the second wavelength from the exit side of the coupling optical system,
Among the plurality of lenses, the wavefront of the reflected light of the third wavelength reflected by the third wavelength reflecting lens that has been coated in advance to reflect the light of the third wavelength is a desired wavefront. An optical adjustment method for an imaging optical system, wherein the position of the third wavelength reflection lens is adjusted.

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