JP2022161124A - Wavefront measuring device, wavefront measuring method, and manufacturing method for optical system and optical element - Google Patents

Abstract

To provide a compact wavefront measuring device capable of calibrating a system error in a short time and with high accuracy.SOLUTION: A wavefront measuring device (1) includes: a first light source unit (100) for emitting first light toward a test object; an optical system (50) for guiding the first light through the test object; a light receiving unit (80) for receiving the first light from the optical system; a calculation unit (90) for calculating a wavefront of the test object based on a signal corresponding to the first light output from the light receiving unit and reference data; a second light source unit (200) for emitting second light; a first reflecting unit (60) arranged between the optical system and the light receiving unit in an optical path of the first light and reflecting the second light toward the optical system; and a second reflecting unit (40) arranged between the first light source unit and the optical system in the optical path of the first light and reflecting the second light from the optical system toward the light receiving unit, where the calculation unit calculates the reference data based on a signal corresponding to the second light output from the light receiving unit.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wavefront measuring device for measuring a transmitted wavefront of an optical system.

Conventionally, single-pass transmission wavefront measurement using a wavefront sensor has been used to evaluate the performance of test objects such as optical systems and optical elements. In order to measure the transmitted wavefront of the object with high accuracy, it is necessary to calibrate the system error of the wavefront measuring device.

In Patent Document 1, a transmitted wavefront at a plurality of object height coordinates of an optical system to be measured is measured, a predetermined aberration component is extracted from the wavefront data, and a system error is corrected using the predetermined aberration component and decentration aberration sensitivity. An eccentricity measuring device for separately measuring the eccentricity of an optical system to be measured is disclosed. In Patent Document 2, the relative positional relationship between the optical system to be measured and the measuring device is changed to measure the transmitted wavefront of the optical system to be measured, and the wavefront data and the relative positional relationship are used to calibrate the system error. A wavefront measuring device for measuring the wavefront of an analysis optical system is disclosed.

Japanese Patent No. 6072317 Japanese Patent Application Laid-Open No. 2006-30016

However, the eccentricity measuring device disclosed in Patent Document 1 requires a plurality of off-axis wavefront measurements, so it takes time to calibrate the system error. In addition, when the test object is a lens with a large diameter, the eccentricity measuring device becomes large.

The wavefront measurement device disclosed in Patent Document 2 is based on the premise that the state of the optical elements inside the optical system to be measured and the measuring device does not change when the relative positional relationship between the optical system to be measured and the measuring device is changed. Calibrate the system error as However, when the optical axis of the optical system to be measured or the measuring device is oriented horizontally, the change in the relative positional relationship (rotation about the optical axis) causes self-weight deformation, which changes the state of the internal optical elements. Therefore, the system error calibration accuracy is degraded.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a compact wavefront measuring apparatus, a wavefront measuring method, an optical system manufacturing method, and an optical element manufacturing method that are capable of calibrating system errors in a short time and with high accuracy. do.

A wavefront measuring device as one aspect of the present invention includes a first light source unit that emits first light toward a test object, and an optical system that guides the first light through the test object. a light receiving section for receiving the first light from the optical system, a signal corresponding to the first light output from the light receiving section, and reference data to determine the wavefront of the test object a calculating unit for calculating; a second light source unit for emitting second light; and a first reflecting portion that is arranged between the first light source portion and the optical system in the optical path of the first light, and receives the second light from the optical system. and a second reflecting portion that reflects toward the light receiving portion, and the calculating portion calculates the reference data based on a signal corresponding to the second light output from the light receiving portion.

Other objects and features of the invention are illustrated in the following examples.

According to the present invention, it is possible to provide a compact wavefront measuring device, a wavefront measuring method, an optical system manufacturing method, and an optical element manufacturing method that are capable of calibrating system errors in a short time and with high accuracy. .

1 is a schematic configuration diagram of a wavefront measuring device in Example 1. FIG. 4 is a flow chart of a wavefront measurement method in Example 1. FIG. FIG. 2 is a layout diagram for measurement of system errors occurring in the half mirror and the wavefront sensor in Example 1; FIG. 10 is a schematic configuration diagram of a wavefront measuring device in Example 2; FIG. 11 is a schematic configuration diagram of a wavefront measuring device in Example 3; It is a manufacturing-process figure of the manufacturing method of an optical system. It is a manufacturing-process figure of the manufacturing method of an optical element.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, referring to FIG. 1, a wavefront measuring apparatus according to a first embodiment of the present invention will be described. FIG. 1 is a schematic configuration diagram of a wavefront measuring device 1 in this embodiment.

The wavefront measuring device 1 includes light sources 10 and 11, fibers 20 and 21, half mirrors 40 and 60, a relay optical system (optical system) 50, a collimator lens 70, a wavefront sensor (a light receiving unit such as a Shack-Hartmann sensor) 80, a computer ( calculation unit) 90. With such a configuration, the wavefront measuring device 1 measures the transmitted wavefront of the test object 30 . In this embodiment, the test object 30 is an optical system configured by combining a plurality of lenses (for example, a large-aperture super-telephoto lens).

FIG. 1A shows the optical path of test light passing through the test object 30 . The light source 10 is, for example, a semiconductor laser or an LED, and emits first light (divergent light) 1000 through a fiber (single mode fiber) 20 . In this embodiment, the light source 10 and the fiber 20 constitute a first light source system (first light source section) 100 .

The first light 1000 incident on and transmitted through the test object 30 becomes a large flux of substantially parallel light, and enters the half mirror (second reflecting section) 40 . One surface of the half mirror 40 is an optical flat on which an antireflection film is formed, and the other surface is an optical flat (reflection surface) that transmits part of the light and reflects the rest. The reflective surface has a high degree of flatness (eg λ/20).

The first light 1000 transmitted through the half mirror 40 is reduced in the relay optical system 50 into a luminous flux of an appropriate size, transmitted through the half mirror 60 and received by the wavefront sensor 80 . A signal of the first light 1000 received by the wavefront sensor 80 is sent to the computer (calculation unit) 90 .

FIG. 1B shows the optical path of the reference light that does not pass through (pass through) the test object 30 . The light source 11 emits second light (divergence light) 2000 having substantially the same wavelength as the light source 10 through the fiber 21 . The second light 2000 passes through a collimator lens (for example, an objective lens) 70 and becomes substantially parallel light with substantially no aberration. The luminous flux size of the second light 2000 that has become substantially parallel light is the same as or larger than the luminous flux size of the first light 1000 incident on the wavefront sensor 80 . In this embodiment, the light source 11 , the fiber 21 and the collimator lens 70 constitute a second light source system (second light source section) 200 .

The second light 2000 emitted from the second light source system 200 is reflected by the half mirror (first reflecting section) 60, and travels in the direction opposite to the travel direction of the first light 1000, forming a second light 2000A. becomes. The second light 2000A is expanded by the relay optical system 50 and enters the half mirror (second reflecting section) 40 . The second light 2000A is reflected by the half mirror 40 and becomes second light 2000B that travels in the same direction as the first light 1000 travels.

The second light 2000 B is reduced by the relay optical system 50 , transmitted through the half mirror 60 and received by the wavefront sensor 80 . The luminous flux size of the second light 2000B incident on the wavefront sensor 80 is the same as or larger than the luminous flux size of the first light 1000 incident on the wavefront sensor 80 . A signal of second light 2000 B received by wavefront sensor 80 is sent to computer 90 . The computer 90 calculates reference data from the signal of the second light 2000B, and calculates the transmitted wavefront of the test object 30 based on the signal of the first light 1000 and the reference data.

In this embodiment, the wavefront is calculated using the Shack-Hartmann principle. That is, the wavefront sensor 80 is a Shack-Hartmann sensor with a microlens array. When parallel light with no wavefront aberration is incident on the Shack-Hartmann sensor, a spot array image having the same period as the microlens array is picked up. On the other hand, when light with wavefront aberration is incident on the Shack-Hartmann sensor, each spot position of the spot array image shifts in proportion to the inclination of the wavefront of the light incident on each microlens. A wavefront is calculated based on the shift amount of the spot position.

Next, referring to FIG. 2, a measurement procedure (wavefront measurement method) of the transmitted wavefront of the test object 30 in this embodiment will be described. FIG. 2 is a flow chart of the wavefront measurement method.

First, in step S10, the wavefront sensor 80 detects the first light 1000 emitted from the first light source system 100 toward the test object 30 and transmitted through the test object 30 and the relay optical system 50 once (single pass). Light is received (first light receiving step). At this time, the second light source system 200 is powered off or the second light 2000 is blocked so that the light emitted from the second light source system 200 is not mixed. A signal W _meas of the first light 1000 received by the wavefront sensor 80 includes not only the transmitted wavefront W _sample of the test object 30 but also the system error W _REF of the wavefront measuring device 1 . The system error W _REF is the _{sum of the transmitted wavefront W relay of the relay optical system 50 , the transmitted wavefront W HMt of} the half mirror 60 , and the detection error W _SHS generated by the wavefront sensor 80 . Note that the light itself emitted from the first light source system 100 has substantially no aberration due to the spatial filter effect of the fiber 20 . A signal W _meas of the first light 1000 is represented by Equation 1 below.

Subsequently, in step S20, the wavefront sensor 80 receives the second light 2000B that is emitted from the second light source system 200, passes through the relay optical system 50 twice (double-passes) via the half mirror 60 and the half mirror 40. (second light receiving step). At this time, the first light source system 100 is powered off or the first light 1000 is blocked so that the light emitted from the first light source system 100 is not mixed. A signal W _ref1 corresponding to the second light received by the wavefront sensor 80 includes three elements (the transmitted wavefront W relay of the relay optical system 50 and the transmitted wavefront W _HMt of the half mirror 60 ₎ that constitute the system error of the wavefront measuring device 1 , contains information on the detection error W _SHS of the wavefront sensor 80 . Note that the light itself emitted from the second light source system 200 is emitted from the fiber 21 and collimated by the collimator lens 70 whose aberration is corrected, so that the light itself has substantially no aberration. The reflected wavefront at the half mirror 40 is also so small that it can be ignored. The signal W _ref1 contains information on the reflected wavefront W _HMr of the half mirror 60 . That is, the signal W _ref1 of the second light 2000B is represented by the following equation (2).

Subsequently, in step S30, the computer 90 calculates reference data W _REF corresponding to the system error based on the signal W _ref1 of the second light 2000B (first calculation step). Normally, the transmitted wavefront W _HMt of the half mirror 60, the reflected wavefront W _HMr , and the detection error W _SHS generated by the wavefront sensor 80 are so small as to be W _HMt ~W _HMr ~W _SHS ~0. That is, the reference data (system error) W _REF substantially corresponds to the transmitted wavefront W _relay of the relay optical system 50, and is represented by the following equation (3).

If the amount of system error derived from the half mirror 60 and the wavefront sensor 80 cannot be ignored, it can be measured by the following method. FIG. 3 is a measurement arrangement diagram of system errors occurring in the half mirror 60 and the wavefront sensor 80. As shown in FIG.

As shown in FIG. 3A , in the wavefront measuring device 1 , a mirror (third reflecting section) 43 having high flatness is inserted between the relay optical system 50 and the half mirror 60 . The second light 2000A emitted from the second light source system 200 and reflected by the half mirror 60 is reflected by the mirror 43 and becomes the second light 2000C traveling in the same direction as the traveling direction of the first light 1000. . The second light 2000</b>C passes through the half mirror 60 and is received by the wavefront sensor 80 . A signal W _ref2 of the second light 2000C received by the wavefront sensor 80 is represented by the following equation (4). Note that the reflected wavefront at the mirror 43 can be ignored.

In general, since the reflecting surface of the half mirror has high flatness, the reflected wavefront is so small that it can be ignored. On the other hand, the transmitted wavefront of the half mirror (especially when the half mirror is a cube beam splitter) may not be negligible. That is, W _HMt >>W _{HMr ˜0} . Therefore, the reference data (system error) W _REF is expressed as the following equation (5) from equations (1), (2), and (4).

If it is desired to calibrate the reflected wavefront _WHMr of the half mirror 60 as well, a system as shown in FIG. 3B is constructed. That is, from between the relay optical system 50 and the half mirror 60, the third light 3000 having substantially the same wavelength as the first light is directed to the wavefront sensor 80 in the same direction as the traveling direction of the first light 1000. shoot towards. Then, the signal of the third light 3000 transmitted through the half mirror 60 and received by the wavefront sensor 80 is acquired.

In FIG. 3B, a mirror (fourth reflecting section) 75 having high flatness is arranged between the relay optical system 50 and the half mirror 60, and a third light source system (third light source section) 300 The third light 3000 from is guided from the side. A third light source system 300 is composed of a light source 12 , a fiber 22 and a collimator 71 . The signal of the third light 3000 may be obtained before assembling the wavefront measuring device 1 . Instead of using the mirror 75, the relay optical system 50 may be removed and the third light source system 300 may be placed on the optical path of the first light 1000 instead of the relay optical system. A second light source system 200 may be arranged instead of the third light source system 300 and the light emitted from the second light source system 200 may be used as the third light 3000 . A signal W _ref3 of the third light 3000 received by the wavefront sensor 80 is represented by the following equation (6).

The reference data (system error) W _REF is expressed as the following equation (7) from equations (1), (2), (4), and (6).

Finally, in step S40, the computer 90 calculates the transmitted wavefront W _sample of the test object 30 based on the signal W _meas of the first light 1000 and the reference data W _REF (second calculation step). The transmitted wavefront W _sample of the test object 30 is expressed by the following equation ( 8).

When substituting the respective signals W _meas , W _ref1 , W _ref2 , and W _ref3 received by the wavefront sensor 80 into the above equation, the data format may be a two-dimensional array of wavefronts, or may be a wavefront-specific function (for example, Zernike function) may be used. Alternatively, each spot position (information on positions of a plurality of point images) of a wavefront sensor (Shack-Hartmann sensor) may be used. Normally, the Shack-Hartmann sensor analyzes the wavefront of the test light with reference to the spot position when the non-aberration light is incident. In this embodiment, instead of that, the shift amount of the spot position W _meas of the first light 1000 is calculated based on the spot position of the reference data (system error) W _REF , so that the system error calibrated test object Thirty transmitted wavefronts are obtained. With the above configuration, in this embodiment, the system error of the wavefront measuring apparatus 1 can be calibrated and the transmitted wavefront of the test object 30 can be measured.

As described above, in this embodiment, the wavefront measuring device 1 includes the first light source unit (first light source system 100), the optical system (relay optical system 50), the light receiving unit (wavefront sensor 80), and the calculating unit (computer 90). The wavefront measuring device also has a second light source section (second light source system 200), a first reflecting section (half mirror 60), and a second reflecting section (half mirror 40). The first light source section emits first light 1000 toward the test object 30 . The optical system guides the first light through the test object (adjusts the optical path and beam diameter). The light receiving section receives the first light from the optical system. The calculator calculates the wavefront of the object based on the signal corresponding to the first light output from the light receiver and the reference data. The second light source unit emits second light 2000 . The first reflecting section is arranged between the optical system and the light receiving section in the optical path of the first light, and reflects the second light toward the optical system. The second reflecting section is arranged between the first light source section and the optical system in the optical path of the first light, and reflects the second light from the optical system toward the light receiving section. The calculator calculates reference data based on the signal corresponding to the second light output from the light receiver. Preferably, the reference data is information regarding the positions of the plurality of point images on the light receiving section.

Preferably, the wavefront measuring device is arranged between the optical system and the first reflecting section in the optical path of the first light, and reflects the second light from the first reflecting section toward the light receiving section. It has 3 reflectors (mirrors 43). The calculator calculates reference data based on a signal corresponding to the second light that has passed through the third reflector and is output from the light receiver. Further preferably, the light receiving section receives the second light transmitted through the first reflecting section.

Preferably, the wavefront measuring device includes a third light source unit (third light source system 300) that emits the third light 3000, and a It has a fourth reflecting portion (mirror 75) arranged to reflect the third light toward the light receiving portion. The calculator calculates reference data based on the signal corresponding to the third light output from the light receiver.

In a general single-pass wavefront measurement device, an almost aberration-free light (reference light ) is used to calibrate the system error of the wavefront measurement device. However, in the case of an object with a large aperture, it is difficult to prepare a substantially aberration-free light beam with a diameter larger than that aperture. Therefore, in this embodiment, instead of that, from the vicinity of the wavefront sensor where the luminous flux of the test light becomes small, the luminous flux size of the test light is the same as the test light or the luminous flux size of the test light is directed in the opposite direction to the test light. It emits substantially stigmatic light of a luminous flux larger than . Then, it is reflected by a half-mirror placed in front of the test object to generate reference light that passes through the same optical path as the test light. Also, the mismatch between the single pass (test light) and the double pass (reference light) is corrected by calculation. This embodiment makes use of the fact that it is easy to prepare substantially aplanatic light for a small luminous flux, and that it is easy to prepare a reflecting surface with a high degree of flatness even with a large diameter. .

Moreover, in this embodiment, it is not necessary to rotate the test object and measure a plurality of wavefronts. Since the second light source system can be configured with only small optical elements, the size of the wavefront measuring apparatus can be suppressed. As described above, by using this embodiment, it is possible to calibrate the system error of the wavefront measuring apparatus in a short measurement time while suppressing the size of the wavefront measuring apparatus.

In the measurement flow of this embodiment, the signal of the first light 1000 including information on the transmitted wavefront of the object is acquired, and then the signal of the second light 2000B including information on the system error is acquired. can be reversed. If the system error changes little over time, step S20 and step S30 may be omitted in the measurement flow if reference data is obtained by executing step S20 and step S30 in advance.

In this embodiment, a half mirror 40 is permanently provided as a second reflecting section. Alternatively, however, a detachable mirror may be prepared as the second reflecting section and attached only at step S20. In this embodiment, the half mirror 60 and the second light source system 200 are permanently installed, but instead, the detachable half mirror 60 and the second light source system 200 are prepared and attached only at step S20. You may In this embodiment, an objective lens is used as the collimator lens 70 corrected for aberrations. Alternatively, a large-aperture lens (for example, a super-telephoto lens) may be prepared, and only a small light flux in the paraxial area may be extracted as the second light 2000 . The wavefront in the paraxial region can be regarded as substantially stigmatic. In this embodiment, the light source 10 of the first light source system 100 and the light source 11 of the second light source system 200 are prepared separately. Alternatively, light source 11 may be omitted by splitting light from one light source (eg, light source 10) into fibers 20, 21, respectively.

In this embodiment, a Shack-Hartmann sensor with a microlens array is used as the wavefront sensor 80, but it is not limited to this. Alternatively, wavefront sensor 80 may use a shearing interferometer (Talbot interferometer) with a Hartmann mask. The Hartmann mask may be either a two-dimensional phase grating or a two-dimensional absorption grating. In the shearing interferometer, the wavefront can be calculated by the Fourier transform method from the distortion of the self-image behind the Hartmann mask. Or as a Hartmann mask, using a pinhole array (an array in which the pinholes are so far apart that the interference between the light transmitted through one pinhole and the light transmitted through the adjacent pinhole is negligible), the Shack-Hartmann sensor and A wavefront may be recovered by a similar principle.

Alternatively, in this embodiment, a method of calculating the wavefront using the intensity information of the test light may be adopted. This method is as follows. That is, the wavefront sensor 80 is arranged by fixing an image sensor (not including a microlens array or a Hartmann mask) on a rectilinear stage. Then, a plurality of images are picked up while driving the rectilinear stage. The computer 90 calculates the transmitted wavefront of the test object 30 based on the captured image. The calculation method for calculating the wavefront from the image may be a method using an intensity transport equation or a method of performing optimization calculation based on a specific initial value of the wavefront. Alternatively, the wavefront may be calculated using artificial intelligence (AI) that has undergone machine learning of the relationship between the wavefront and the image.

Next, a wavefront measuring device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a schematic configuration diagram of the wavefront measuring device 2 in this embodiment.

FIG. 4A is a diagram showing an arrangement for measuring the wavefront of the first light 1000 that has passed through the test object 30. FIG. The wavefront measuring device 2 has a first light source system 100, a diffraction element 110, lenses 150a, 150b, 151b, 152b, mirrors 120, 122, wavefront sensors 80, 81, 82, and a computer 90. The wavefront measuring device 2 also has a detachable second light source system 200 , a mirror 41 and a half mirror (pellicle beam splitter) 61 . The test object 30 is an optical system configured by combining a plurality of lenses. A first light source system 100 includes light sources 10 , 11 , 12 and a pinhole array 25 , and emits test light from a plurality of image heights of a test object 30 . The wavefront measuring device 2 measures the wavefronts of a plurality of test light beams emitted from the plurality of image heights and transmitted through the test object 30 .

The lights emitted from the light sources 10, 11, and 12 respectively pass through a plurality of pinholes of the pinhole array 25, become a plurality of first lights 1000, 1001, and 1002 as diverging waves, and enter the test object 30. . A plurality of first lights 1000, 1001, and 1002 that have passed through the test object 30 are emitted from the diffraction element 110 as −1st-order diffracted light 1000, 0th-order diffracted light 1001, and +1st-order diffracted light 1002, respectively.

The first lights 1000, 1001, 1002 are separated from each other near the focal point after passing through the lens 150a. The first light 1001 travels straight and is received by the wavefront sensor 81 through the lens 151b. On the other hand, the first lights 1000 and 1002 are respectively reflected by mirrors 120 and 122 arranged near the focal points, pass through lenses 150b and 152b, and are received by wavefront sensors 80 and 82, respectively. For the first light 1000, the lens 150a, the mirror 120, and the lens 150b correspond to a relay optical system. Similarly, the lens 150a and the lens 151b correspond to the relay optical system for the first light 1001, and the lens 150a, the mirror 122, and the lens 152b correspond to the relay optical system for the first light 1002.

Signals corresponding to the first lights 1000 , 1001 and 1002 are output to the computer 90 from the wavefront sensors 80 , 81 and 82 that have received the first lights 1000 , 1001 and 1002 respectively. The computer 90 uses the signals corresponding to the plurality of first lights 1000, 1001, 1002 and the plurality of reference data to convert the first lights 1000, 1001, 1002 at the plurality of image heights transmitted through the test object 30. Calculate the wavefront. A plurality of reference data are measured in advance as follows.

In this embodiment, reference data corresponding to each of a plurality of image heights of the object 30 are measured one image height at a time. FIG. 4B is a layout diagram for measuring reference data corresponding to the first light 1000. FIG. A mirror (second reflecting portion) 41 is inserted between the test object 30 and the diffraction element 110, and a half mirror (first reflecting portion) 61 is inserted between the lens 50b and the wavefront sensor 80. FIG. A second light source system 200 is installed near the half mirror 61 . The mirror 41 adjusts the angle so that the direction of the normal to the reflecting surface matches the traveling direction of the first light 1000 .

The second light source system 200 includes a light source 13 that emits light of substantially the same wavelength as the light source 10, a pinhole 26, and an aberration-corrected collimator lens 70. of light 2000 is emitted. The luminous flux size of the second light 2000 emitted from the second light source system 200 is the same as or larger than the luminous flux size of the first light 1000 incident on the wavefront sensor 80 . The second light 2000 emitted from the second light source system 200 is reflected by the half mirror 61 and becomes second light 2000A traveling in the direction opposite to the traveling direction of the first light 1000 . The second light 2000A is magnified by the relay optical system (lens 150b, mirror 120, lens 150a) and enters the mirror 41. FIG.

The second light 2000A is reflected by the mirror 41 and becomes the second light 2000B that travels in the same direction as the first light 1000 travels. The positions of the second light source system 200 and the half mirror 61 are adjusted so that the traveling direction of the second light 2000B and the traveling direction of the first light 1000 are aligned. The second light 2000 B is reduced by the relay optical system, transmitted through the half mirror 61 and received by the wavefront sensor 80 . A signal of second light 2000 B received by wavefront sensor 80 is sent to computer 90 . Computer 90 calculates reference data from the signal of second light 2000B.

For the first lights 1001 and 1002 as well, the mirror 41, the half mirror 61, and the second light source system 200 are appropriately arranged to obtain respective reference data.

Next, with reference to FIG. 5, a wavefront measuring device according to a third embodiment of the present invention will be described. FIG. 5 is a schematic configuration diagram of the wavefront measuring device 3 in this embodiment.

The wavefront measuring device 3 has a first light source system 100 , a second light source system 200 , a relay optical system 53 , a half mirror (cube beam splitter) 62 , a wavefront sensor 80 and a computer 90 . The wavefront measuring device 3 also has a detachable spherical mirror 42 as a second reflecting section. In this embodiment, the test object 31 is a molded lens (optical element). A first light source system 100 is composed of a light source 10 and a fiber 20 . The second light source system 200 is composed of the light source 10 and the fiber 21 and shares the light source 10 with the first light source system 100 .

FIG. 5A is a diagram showing an arrangement for measuring the wavefront of the first light 1000 transmitted through the test object 31. FIG. A first light (divergent light) 1000 emitted from the light source 10 through the fiber 20 passes through the test object 31 and converges, passes through the relay optical system 53, and becomes substantially parallel light. The first light 1000 passes through the half mirror 62 and is received by the wavefront sensor 80 . A signal corresponding to the first light is output to the computer 90 from the wavefront sensor 80 that has received the first light 1000 . The computer 90 calculates the wavefront of the first light 1000 transmitted through the test object 31 using the signal corresponding to the first light and the reference data. Reference data are measured as follows.

FIG. 5B is a diagram showing an arrangement for measuring reference data. A spherical mirror 42 is inserted between the first light source system 100 and the relay optical system 53 . The second light (diverging light) 2000 emitted from the light source 10 through the fiber 21 becomes substantially parallel light by the collimator lens 70, is reflected by the half mirror 62, and travels in the direction opposite to the traveling direction of the first light 1000. becomes the second light 2000A. The second light 2000 A passes through the relay optical system 53 and enters the spherical mirror 42 .

The second light 2000A is reflected by the spherical mirror 42 and becomes second light 2000B that travels in the same direction as the first light 1000 travels. The second light 2000 B passes through the relay optical system 53 and the half mirror 62 and is received by the wavefront sensor 80 . A signal of second light 2000 B received by wavefront sensor 80 is sent to computer 90 . Computer 90 calculates reference data from the signal of second light 2000B.

Next, with reference to FIG. 6, a method for manufacturing an optical system according to Example 4 of the present invention will be described. FIG. 6 is a flow chart showing the manufacturing method of the optical system in this embodiment. The result of the wavefront measured using the wavefront measuring device 1 of the first embodiment, the wavefront measuring device 2 of the second embodiment, or the wavefront measuring device 3 of the third embodiment is applied to the manufacturing method of the optical system (test object 30). Feedback is possible.

First, in step S101, an optical system is assembled using optical elements, and the position of each element is adjusted (optical system assembly adjustment). Subsequently, in step S102, the optical performance (optical precision) of the assembled and adjusted optical system is evaluated. Here, the evaluation of the optical performance of the optical system is performed using the result of the wavefront measured using the wavefront measuring apparatus 1 of the first embodiment or the wavefront measuring apparatus 2 of the second embodiment. If the optical performance is insufficient in step S102, the process returns to step S101, and the optical system is assembled and adjusted again. On the other hand, if the optical performance is satisfied in step S102, this flow relating to the optical system manufacturing method ends.

FIG. 7 is a flow chart showing a method of manufacturing an optical element using molding. The optical element is manufactured through an optical element designing process (step S201), a mold designing process (step S202), and an optical element molding process using the designed mold (step S203). The shape accuracy of the molded optical element is evaluated (step S204). If the precision is insufficient, the mold is corrected (step S207) and molding is performed again. On the other hand, when the shape accuracy is good, the optical performance of the optical element is evaluated (step S205). If the optical performance is poor, the optical surfaces are corrected (step S208) and the optical elements are redesigned. On the other hand, if the optical performance is satisfied in step S205, the process proceeds to the mass production of optical elements (step S206). The wavefront measuring device 3 of Example 3 can be used for the optical performance evaluation in step S205. It should be noted that the method of manufacturing an optical element in this embodiment can be applied to manufacture of an optical element by grinding or polishing instead of using a mold.

According to each embodiment, it is possible to provide a compact wavefront measuring apparatus, a wavefront measuring method, an optical system manufacturing method, and an optical element manufacturing method that can calibrate system errors in a short time and with high accuracy. can.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist.

1 Wavefront measurement device 40 Half mirror (second reflecting unit)
50 relay optical system (optical system)
60 half mirror (first reflecting part)
80 Wavefront sensor (light receiving part)
90 computer (calculation unit)
100 first light source system (first light source unit)
200 second light source system (second light source unit)

Claims (13)

a first light source unit that emits the first light toward the test object;
an optical system that guides the first light that has passed through the test object;
a light receiving unit that receives the first light from the optical system;
a calculation unit that calculates a wavefront of the test object based on a signal corresponding to the first light output from the light receiving unit and reference data;
a second light source unit that emits a second light;
a first reflecting section disposed between the optical system and the light receiving section in the optical path of the first light and reflecting the second light toward the optical system;
a second reflecting section disposed between the first light source section and the optical system in the optical path of the first light and reflecting the second light from the optical system toward the light receiving section; , has
The wavefront measuring device, wherein the calculator calculates the reference data based on a signal corresponding to the second light output from the light receiver. a third optical system disposed between the optical system and the first reflecting section in the optical path of the first light, and reflecting the second light from the first reflecting section toward the light receiving section; further having a reflective part;
2. The calculation unit according to claim 1, wherein the calculation unit calculates the reference data based on a signal corresponding to the second light that has passed through the third reflection unit and is output from the light receiving unit. wavefront measurement device. 3. The wavefront measuring apparatus according to claim 1, wherein the light receiving section receives the second light transmitted through the first reflecting section. a third light source unit that emits a third light;
a fourth reflector disposed between the optical system and the first reflector in the optical path of the first light and reflecting the third light toward the light receiver;
The wavefront according to any one of claims 1 to 3, wherein the calculator calculates the reference data based on a signal corresponding to the third light output from the light receiver. measuring device. The wavefront measuring device according to any one of claims 1 to 4, wherein the light receiving section has a microlens array. The wavefront measuring apparatus according to any one of claims 1 to 5, wherein the light receiving section has a Hartmann mask. The wavefront measuring device according to any one of claims 1 to 6, wherein the light receiving unit is an image sensor. The wavefront measuring apparatus according to any one of claims 1 to 6, wherein the reference data is information on positions of a plurality of point images on the light receiving section. The wavefront measuring device according to any one of claims 1 to 8, wherein the first reflector is detachable. The wavefront measuring device according to any one of claims 1 to 9, wherein the second light source unit is detachable. a first light receiving step of using the light receiving unit to receive the first light emitted from the first light source unit and passing through the test object and the optical system;
A second light from a second light source is reflected using a first reflector disposed between the optical system and the light receiving unit, and the first light source and the optical system are reflected. a second light-receiving step of reflecting the second light using a second reflecting section disposed therebetween and receiving the second light using the light-receiving section;
a first calculation step of calculating reference data based on a signal corresponding to the second light output from the light receiving unit, using a calculation unit;
A wavefront measuring method, comprising: a second calculating step of calculating a wavefront of the test object based on the signal corresponding to the first light and the reference data, using the calculating unit. assembling an optical system;
and evaluating the optical performance of the assembled optical system by measuring the wavefront of the assembled optical system using the wavefront measurement method according to claim 11. Method. machining the optical element;
and evaluating the optical performance of the processed optical element by measuring the wavefront of the processed optical element using the wavefront measurement method according to claim 11. Method.

Images