Wavefront measuring device, wavefront measuring method, and method for manufacturing optical system and optical element

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

[Technical field]

[0001] The present invention relates to a wavefront measuring device that measures a transmitted wavefront of an optical system. [Background technology]

[0002] Conventionally, single-pass transmitted wavefront measurement using a wavefront sensor is used to evaluate the performance of test objects such as optical systems and optical elements. To measure the transmitted wavefront of a test object with high accuracy, it is necessary to calibrate the system error of the wavefront measurement device.

[0003] Patent Document 1 discloses an eccentricity measurement device that measures the transmitted wavefront of a test optical system at multiple object height coordinates, extracts a predetermined aberration component from the wavefront data, and measures the eccentricity of the test optical system by separating a system error using the predetermined aberration component and eccentricity aberration sensitivity. Patent Document 2 discloses a wavefront measurement device that measures the transmitted wavefront of the test optical system by changing the relative positional relationship between the test optical system and a measurement device, calibrates the system error using the wavefront data and the relative positional relationship, and measures the wavefront of the test optical system. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6072317 [Patent Document 2] JP 2006-30016 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the decentering amount measurement device disclosed in Patent Document 1 requires multiple off-axis wavefront measurements, and therefore requires a lot of time to calibrate the system error. Also, when the test object is a large-diameter lens, the decentering amount measurement device becomes large.

[0006] The wavefront measuring device disclosed in Patent Document 2 calibrates system errors on the premise that the state of the optical elements inside the test optical system and the measuring device does not change when the relative positional relationship between the test optical system and the measuring device is changed. However, when the optical axis of the test optical system or the measuring device is oriented horizontally, a change in the relative positional relationship (rotation about the optical axis) causes deformation due to its own weight, which changes the state of the internal optical elements, thereby reducing the accuracy of system error calibration.

[0007] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a small wavefront measuring device, a wavefront measuring method, a manufacturing method for an optical system, and a manufacturing method for an optical element, which are capable of calibrating system errors in a short time and with high accuracy. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a wavefront measuring device. , covered For the inspection The first light a first light source unit that emits light; and Passed an optical system that guides the first light; The object to be inspected and the optical system a light receiving unit that receives the first light; , No. a second light source unit that emits a second light, and a light path of the first light Leave a light receiving unit that receives the second light from the optical system and a light receiving unit; fart reflection to make A first reflecting portion and an optical path of the first light Leave A light source unit is disposed between the first light source unit and the optical system. ,before The second light is received by the light receiving unit. fart reflection to make A second reflector and a calculation unit that calculates reference data based on a second signal output by the light receiving unit based on the second light, and calculates a wavefront of the test object based on a first signal output by the light receiving unit based on the first light and the reference data. .

[0009] Other objects and features of the present invention are illustrated in the following examples. Effect of the Invention

[0010] According to the present invention, it is possible to provide a small wavefront measuring device, a wavefront measuring method, a manufacturing method for an optical system, and a manufacturing method for an optical element, which are capable of calibrating system errors in a short time and with high accuracy. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram of a wavefront measuring device in a first embodiment. [Diagram 2] 4 is a flowchart of a wavefront measuring method in the first embodiment. [Diagram 3] FIG. 4 is a diagram showing a measurement arrangement for measuring a system error occurring in a half mirror and a wavefront sensor in the first embodiment. [Figure 4] FIG. 11 is a schematic configuration diagram of a wavefront measuring device in a second embodiment. [Diagram 5] FIG. 11 is a schematic configuration diagram of a wavefront measuring device in a third embodiment. [Figure 6] 1A to 1C are manufacturing process diagrams of a manufacturing method for an optical system. [Figure 7] 1A to 1C are manufacturing process diagrams of a manufacturing method for an optical element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. EXAMPLES

[0013] First, a wavefront measuring device in a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic configuration diagram of a wavefront measuring device 1 in this embodiment.

[0014] The wavefront measuring device 1 is configured to include light sources 10, 11, fibers 20, 21, half mirrors 40, 60, a relay optical system (optical system) 50, a collimator lens 70, a wavefront sensor (light receiving unit such as a Shack-Hartmann sensor) 80, and a computer (calculation unit) 90. In this configuration, the wavefront measuring device 1 measures the transmitted wavefront of a test object 30. In this embodiment, the test object 30 is an optical system (for example, a large-aperture super telephoto lens) configured by combining multiple lenses.

[0015] 1(A) shows the optical path of test light passing through a test object 30. A light source 10 is, for example, a semiconductor laser or an LED, and emits a first light (diverging light) 1000 via a fiber (single mode fiber) 20. In this embodiment, the light source 10 and the fiber 20 configure a first light source system (first light source unit) 100.

[0016] The first light 1000 incident on and transmitted through the test object 30 becomes a large beam of approximately parallel light, and is incident on the half mirror (second reflecting section) 40. One surface of the half mirror 40 is an optical flat on which an anti-reflection film is formed, and the other surface is an optical flat (reflective surface) that transmits a portion of the light and reflects the rest. The reflective surface has a high degree of flatness (e.g., λ / 20).

[0017] The first light 1000 transmitted through the half mirror 40 is reduced to a light beam of an appropriate size in the relay optical system 50, 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 a computer (calculation unit) 90.

[0018] 1B shows the optical path of the reference light that does not transmit (pass) through the test object 30. The light source 11 emits a second light (divergent light) 2000 having substantially the same wavelength as that of the light source 10 via a fiber 21. The second light 2000 passes through a collimator lens (e.g., an objective lens) 70 and becomes substantially parallel light with substantially no aberration. The beam size of the substantially parallel second light 2000 is the same as or larger than the beam 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 unit) 200.

[0019] The second light 2000 emitted from the second light source system 200 is reflected by the half mirror (first reflecting section) 60, and becomes the second light 2000A traveling in the opposite direction to the traveling direction of the first light 1000. The second light 2000A is magnified 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 the second light 2000B traveling in the same direction as the traveling direction of the first light 1000.

[0020] The second light 2000B is reduced in size by the relay optical system 50, passes through the half mirror 60, and is received by the wavefront sensor 80. The beam size of the second light 2000B incident on the wavefront sensor 80 is the same as or larger than the beam size of the first light 1000 incident on the wavefront sensor 80. The signal of the second light 2000B received by the wavefront sensor 80 is sent to the 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.

[0021] In this embodiment, the wavefront is calculated using the Shack-Hartmann principle. That is, the wavefront sensor 80 is a Shack-Hartmann sensor equipped with a microlens array. When parallel light without wavefront aberration is incident on the Shack-Hartmann sensor, a spot array image with the same period as the period of the microlens array is captured. On the other hand, when light with wavefront aberration is incident on the Shack-Hartmann sensor, the position of each spot in the spot array image shifts in proportion to the inclination of the wavefront of the light incident on each microlens. The wavefront is calculated based on the shift amount of the spot position.

[0022] Next, a procedure for measuring a transmitted wavefront of the test object 30 (a wavefront measuring method) in this embodiment will be described with reference to Fig. 2. Fig. 2 is a flowchart of the wavefront measuring method.

[0023] First, in step S10, the first light 1000 emitted from the first light source system 100 toward the test object 30 and transmitted once (single pass) through the test object 30 and the relay optical system 50 is received by the wavefront sensor 80 (first light receiving step). At this time, the power supply of the second light source system 200 is turned off or the second light 2000 is blocked so that the light emitted from the second light source system 200 is not mixed in. A signal W of the first light 1000 received by the wavefront sensor 80 is meas is the transmitted wavefront W of the test object 30 sample In addition, the system error W of the wavefront measuring device 1 REF System Error W REF is the transmitted wavefront W of the relay optical system 50. relay and the transmitted wavefront W of the half mirror 60 HMt and the detection error W generated by the wavefront sensor 80 SHS The light emitted from the first light source system 100 is substantially free of aberration due to the spatial filter effect of the fiber 20. meas is expressed by the following Equation 1.

[0024]

number

[0025] Next, in step S20, the second light 2000B emitted from the second light source system 200, passes through the half mirror 60 and the half mirror 40, and is transmitted twice (double pass) through the relay optical system 50, and is received by the wavefront sensor 80 (second light receiving step). At this time, the power supply of the first light source system 100 is turned off or the first light 1000 is blocked so that the light emitted from the first light source system 100 is not mixed in. A signal W corresponding to the second light received by the wavefront sensor 80 is ref1 are three elements constituting the system error of the wavefront measuring device 1 (the transmitted wavefront W relay , the transmitted wavefront W of the half mirror 60 HMt , the detection error W SHSThe light emitted from the second light source system 200 is emitted from the fiber 21 and collimated by the aberration-corrected collimator lens 70, and is therefore substantially aberration-free. The reflected wavefront at the half mirror 40 is also negligibly small. The signal W ref1 is the reflected wavefront W of the half mirror 60 HMr That is, the signal W of the second light 2000B includes ref1 is expressed by the following equation (2).

[0026]

number

[0027] Next, in step S30, the computer 90 calculates the signal W of the second light 2000B. ref1 Based on the reference data W corresponding to the system error REF (first calculation step). Usually, the transmitted wavefront W HMt , reflected wavefront W HMr , and the detection error W SHS is negligibly small, and W HMt ~W HMr ~W SHS ~0. That is, the reference data (system error) W REF is substantially the transmitted wavefront W of the relay optical system 50. relay Therefore, it is expressed by the following equation (3).

[0028]

number

[0029] If the system error due to the half mirror 60 and the wavefront sensor 80 is not negligible, it can be measured by the following method. FIG.

[0030] As shown in FIG. 3A, in the wavefront measuring device 1, a mirror (third reflecting portion) 43 having a high degree of 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 to become the second light 2000C traveling in the same direction as the traveling direction of the first light 1000. The second light 2000C passes through the half mirror 60 and is received by the wavefront sensor 80. A signal W of the second light 2000C received by the wavefront sensor 80 is ref2 is expressed by the following formula (4): Note that the reflected wavefront at the mirror 43 can be ignored.

[0031]

number

[0032] Generally, the reflecting surface of a half mirror has a high degree of flatness, so the reflected wavefront is small enough to be ignored. On the other hand, the transmitted wavefront of the half mirror (especially when the half mirror is a cube-type 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).

[0033]

number

[0034] Suppose the reflected wavefront W HMr 3B is constructed. That is, third light 3000 having approximately the same wavelength as the wavelength of the first light 1000 is emitted from between the relay optical system 50 and the half mirror 60 in the same direction as the traveling direction of the first light 1000 toward the wavefront sensor 80. Then, the signal of the third light 3000 transmitted through the half mirror 60 and received by the wavefront sensor 80 is acquired.

[0035] In FIG. 3B, a mirror (fourth reflecting section) 75 having a high flatness is disposed between the relay optical system 50 and the half mirror 60, and the third light 3000 from the third light source system (third light source section) 300 is guided laterally. The 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 acquired 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 disposed on the optical path of the first light 1000 instead of the relay optical system. The second light source system 200 may be disposed 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. The signal W of the third light 3000 received by the wavefront sensor 80 may be obtained before the wavefront measuring device 1 is assembled. ref3 is expressed by the following equation (6).

[0036]

number

[0037] Reference data (system error) W REF is expressed as the following equation (7) from equations (1), (2), (4), and (6).

[0038]

number

[0039] Finally, in step S40, the computer 90 calculates the signal W of the first light 1000. meas and reference data W REF Based on this, the transmitted wavefront W sample (second calculation step). sample can be expressed as the following equation (8) using equations (1) and (3), or equations (1) and (5), or equations (1) and (7).

[0040]

number

[0041] Each signal W received by the wavefront sensor 80 meas , W ref1 , W ref2 , W ref3 The data format when substituting into the above formula may be a two-dimensional array of the wavefront, or may be coefficients obtained by fitting the wavefront with a specific function (e.g., Zernike function). Alternatively, it may be each spot position (information on the positions of multiple point images) of the wavefront sensor (Shack-Hartmann sensor). Normally, the Shack-Hartmann sensor analyzes the wavefront of the test light based on the spot position when aberration-free light is incident. In this embodiment, instead, reference data (system error) W REF Based on the spot position of the first light 1000, the spot position W meas By calculating the shift amount, the transmitted wavefront of the test object 30 after the system error calibration can be obtained. With the above configuration, in this embodiment, the system error of the wavefront measuring device 1 can be calibrated and the transmitted wavefront of the test object 30 can be measured.

[0042] As described above, in this embodiment, the wavefront measuring device 1 has a first light source unit (first light source system 100), an optical system (relay optical system 50), a light receiving unit (wavefront sensor 80), and a calculation unit (computer 90). The wavefront measuring device also has a second light source unit (second light source system 200), a first reflecting unit (half mirror 60), and a second reflecting unit (half mirror 40). The first light source unit emits a first light 1000 toward the test object 30. The optical system guides the first light through the test object (adjusts the optical path and the light beam diameter). The light receiving unit receives the first light from the optical system. The calculation unit calculates the wavefront of the test object based on a signal corresponding to the first light output from the light receiving unit and the reference data. The second light source unit emits a second light 2000. The first reflecting unit is disposed between the optical system and the light receiving unit in the optical path of the first light, and reflects the second light toward the optical system. The second reflecting unit is disposed between the first light source unit 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 unit. The calculating unit calculates the reference data based on a signal corresponding to the second light output from the light receiving unit. Preferably, the reference data is information regarding the positions of a plurality of point images in the light receiving unit.

[0043] Preferably, the wavefront measuring device has a third reflecting section (mirror 43) 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. The calculating section calculates the reference data based on a signal corresponding to the second light passing through the third reflecting section and output from the light receiving section. Also preferably, the light receiving section receives the second light transmitted through the first reflecting section.

[0044] Preferably, the wavefront measuring device has a third light source unit (third light source system 300) that emits third light 3000, and a fourth reflecting unit (mirror 75) that is disposed between the optical system and the first reflecting unit in the optical path of the first light and reflects the third light toward the light receiving unit. The calculating unit calculates the reference data based on a signal corresponding to the third light output from the light receiving unit.

[0045] In a typical single-path wavefront measuring device, a system error of the wavefront measuring device is calibrated using a substantially aberration-free light (reference light) that passes through the same optical path as the test light and has a light flux that is the same as or larger than the light flux size of the test light. However, in the case of a test object with a large diameter, it is difficult to prepare a substantially aberration-free light with a light flux that is equal to or larger than the diameter of the test light. Instead, in this embodiment, a substantially aberration-free light with a light flux that is the same as or larger than the light flux size of the test light is emitted in the opposite direction to the test light from the vicinity of the wavefront sensor where the light flux of the test light becomes small. Then, the reference light is generated by being reflected by a half mirror arranged just before the test object and passing through the same optical path as the test light. In addition, the mismatch between the single path (test light) and the double path (reference light) is corrected by calculation. This embodiment utilizes the fact that it is easy to prepare a substantially aberration-free light if the light flux is small, and that it can be easily prepared even with a large diameter if the reflecting surface has a high degree of flatness.

[0046] Furthermore, in this embodiment, it is not necessary to rotate the test object to measure multiple wavefronts. Since the second light source system can be constructed using only small optical elements, the size of the wavefront measuring device can be reduced. As described above, by using this embodiment, it is possible to calibrate the system error of the wavefront measuring device in a short measurement time while reducing the size of the wavefront measuring device.

[0047] In the measurement flow of this embodiment, the signal of the first light 1000 containing information on the transmitted wavefront of the test object is acquired, and then the signal of the second light 2000B containing information on the system error is acquired, but the order may be reversed. If the change over time of the system error is small, steps S20 and S30 may be performed in advance to acquire reference data, and steps S20 and S30 may be omitted in the measurement flow.

[0048] In this embodiment, the half mirror 40 is permanently installed as the second reflecting part. However, instead of that, a removable mirror may be prepared as the second reflecting part and installed only at step S20. In this embodiment, the half mirror 60 and the second light source system 200 are permanently installed, but instead of that, a removable half mirror 60 and the second light source system 200 may be prepared and installed only at step S20. In this embodiment, an objective lens is used as the aberration-corrected collimator lens 70. Instead, a large-diameter lens (e.g., a super telephoto lens) may be prepared, and only a small light beam in the paraxial region may be extracted to become the second light 2000. The wavefront in the paraxial region can be considered to be substantially aberration-free. 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 separately prepared. Instead, the light source 11 may be omitted by branching light from one light source (e.g., the light source 10) to each of the fibers 20 and 21.

[0049] In this embodiment, a Shack-Hartmann sensor equipped with a microlens array is used as the wavefront sensor 80, but the present invention is not limited thereto. Alternatively, the wavefront sensor 80 may be a shearing interferometer (Talbot interferometer) equipped with a Hartmann mask. The Hartmann mask may be either a two-dimensional phase type diffraction grating or a two-dimensional absorption type diffraction grating. In the shearing interferometer, the wavefront can be calculated by the Fourier transform method from the distortion of the self-image formed behind the Hartmann mask. Alternatively, a pinhole array (an array in which the pinholes are separated enough that the interference between the light transmitted through one pinhole and the light transmitted through the adjacent pinholes can be ignored) may be used as the Hartmann mask to recover the wavefront using the same principle as the Shack-Hartmann sensor.

[0050] Alternatively, in this embodiment, a method of calculating a wavefront using intensity information of the test light may be adopted. This method is as follows. That is, an image sensor (not including a microlens array or a Hartmann mask) fixed on a linear stage is arranged as a wavefront sensor 80. Then, a plurality of images are captured while driving the linear stage. A computer 90 calculates a transmitted wavefront of the test object 30 based on the captured images. The calculation method of calculating the wavefront from the image may be a method using a transport of intensity equation or a method of performing optimization calculation based on an initial value of a specific wavefront. Alternatively, the wavefront may be calculated using artificial intelligence (AI) that has been machine-learned to learn the relationship between the wavefront and the image. EXAMPLES

[0051] Second Embodiment Next, a wavefront measuring device according to a second embodiment of the present invention will be described with reference to Fig. 4. Fig. 4 is a schematic configuration diagram of the wavefront measuring device 2 according to the present embodiment.

[0052] FIG. 4(A) is a diagram showing an arrangement for measuring the wavefront of the first light 1000 transmitted through the test object 30. 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 formed by combining a plurality of lenses. The first light source system 100 is composed of light sources 10, 11, 12 and a pinhole array 25, and emits test light from a plurality of image heights of the test object 30. The wavefront measuring device 2 measures the wavefronts of a plurality of test light emitted from the plurality of image heights and transmitted through the test object 30.

[0053] The light beams emitted from the light sources 10, 11, and 12 are transmitted through the pinholes of the pinhole array 25 to become the first light beams 1000, 1001, and 1002 as diverging waves, and are incident on the test object 30. The first light beams 1000, 1001, and 1002 transmitted through the test object 30 are output from the diffraction element 110 as −1st order diffracted light 1000, 0th order diffracted light 1001, and +1st order diffracted light 1002, respectively.

[0054] The first light 1000, 1001, and 1002 are separated from each other near the focal point after passing through the lens 150a. The first light 1001 travels straight ahead and passes through the lens 151b before being received by the wavefront sensor 81. Meanwhile, the first light 1000 and 1002 are reflected by the mirrors 120 and 122 disposed near the focal point, respectively, and pass through the lenses 150b and 152b before being received by the wavefront sensors 80 and 82. For the first light 1000, the lens 150a, the mirror 120, and the lens 150b correspond to a relay optical system. Similarly, for the first light 1001, the lenses 150a and 151b correspond to a relay optical system, and for the first light 1002, the lens 150a, the mirror 122, and the lens 152b correspond to a relay optical system.

[0055] Signals corresponding to the first light beams 1000, 1001, 1002 are output from the wavefront sensors 80, 81, 82 that have received the first light beams 1000, 1001, 1002, respectively, to a computer 90. The computer 90 uses the signals corresponding to the first light beams 1000, 1001, 1002 and a plurality of reference data to calculate the wavefronts of the first light beams 1000, 1001, 1002 at a plurality of image heights that have passed through the test object 30. The plurality of reference data are measured in advance as follows.

[0056] In this embodiment, reference data corresponding to each of a plurality of image heights of the test object 30 is measured one image height at a time. FIG. 4B is a layout diagram for measuring reference data corresponding to the first light 1000. 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. The second light source system 200 is installed near the half mirror 61. The angle of the mirror 41 is adjusted so that the direction of the normal to the reflecting surface coincides with the traveling direction of the first light 1000.

[0057] The second light source system 200 is composed of a light source 13 that emits light of approximately the same wavelength as the light source 10, a pinhole 26, and an aberration-corrected collimator lens 70, and emits approximately aberration-free and approximately parallel second light 2000. The beam size of the second light 2000 emitted from the second light source system 200 is the same as or larger than the beam size of the first light 1000 that enters 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 that travels in the opposite direction 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.

[0058] The second light 2000A is reflected by the mirror 41 to become the second light 2000B traveling in the same direction as the first light 1000. 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 coincides with the traveling direction of the first light 1000. The second light 2000B is reduced in size by the relay optical system, passes through the half mirror 61, and is received by the wavefront sensor 80. The signal of the second light 2000B received by the wavefront sensor 80 is sent to the computer 90. The computer 90 calculates reference data from the signal of the second light 2000B.

[0059] 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 positioned, and respective reference data is obtained. EXAMPLES

[0060] Next, a wavefront measuring device according to a third embodiment of the present invention will be described with reference to Fig. 5. Fig. 5 is a schematic configuration diagram of the wavefront measuring device 3 according to the present embodiment.

[0061] 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). The 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 a light source 10 and a fiber 21, and shares the light source 10 with the first light source system 100.

[0062] FIG. 5(A) is a diagram showing an arrangement for measuring the wavefront of the first light 1000 transmitted through the test object 31. The first light (divergent light) 1000 emitted from the light source 10 via the fiber 20 passes through the test object 31 and converges, and passes through the relay optical system 53 to become approximately 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 from the wavefront sensor 80 that has received the first light 1000 to the computer 90. The computer 90 uses the signal corresponding to the first light and the reference data to calculate the wavefront of the first light 1000 transmitted through the test object 31. The reference data is measured as follows.

[0063] 5(B) 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 (divergent light) 2000 emitted from the light source 10 through the fiber 21 is converted into substantially parallel light by the collimator lens 70, reflected by the half mirror 62, and becomes the second light 2000A traveling in the opposite direction to the traveling direction of the first light 1000. The second light 2000A passes through the relay optical system 53 and enters the spherical mirror 42.

[0064] The second light 2000A is reflected by the spherical mirror 42 to become the second light 2000B traveling in the same direction as the first light 1000. The second light 2000B passes through the relay optical system 53 and the half mirror 62, and is received by the wavefront sensor 80. The signal of the second light 2000B received by the wavefront sensor 80 is sent to the computer 90. The computer 90 calculates reference data from the signal of the second light 2000B. EXAMPLES

[0065] Next, a method for manufacturing an optical system according to a fourth embodiment of the present invention will be described with reference to Fig. 6. Fig. 6 is a flowchart showing the method for manufacturing an optical system according to this embodiment. The result of wavefront measurement using the wavefront measuring apparatus 1 of the first embodiment, the wavefront measuring apparatus 2 of the second embodiment, or the wavefront measuring apparatus 3 of the third embodiment can be fed back to a method for manufacturing an optical system (test object 30).

[0066] First, in step S101, an optical system is assembled using optical elements, and the position of each element is adjusted (optical system assembly adjustment). Next, in step S102, the optical performance (optical precision) of the assembled and adjusted optical system is evaluated. Here, the optical performance of the optical system is evaluated using the results of wavefront measurement using the wavefront measuring device 1 of Example 1 or the wavefront measuring device 2 of Example 2. 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 sufficient in step S102, this flow relating to the manufacturing method of the optical system is terminated.

[0067] FIG. 7 is a flow chart showing a method for manufacturing an optical element using molding. An optical element is manufactured through a design step of an optical element (step S201), a design step of a metal mold (step S202), and a molding step of an optical element using the designed metal mold (step S203). The molded optical element is evaluated for its shape accuracy (step S204). If the accuracy is insufficient, the metal mold is corrected (step S207), and molding is performed again. On the other hand, if the shape accuracy is good, the optical performance of the optical element is evaluated (step S205). If the optical performance is low, the optical surface is corrected (step S208), and the optical element is redesigned. On the other hand, if the optical performance is satisfactory in step S205, the process proceeds to mass production of optical elements (step S206). The wavefront measuring device 3 of the third embodiment can be used for the evaluation of the optical performance in step S205. The method for manufacturing an optical element in this embodiment can be applied to the manufacture of optical elements by grinding and polishing, not by using a mold.

[0068] According to each embodiment, it is possible to provide a small wavefront measuring device, a wavefront measuring method, a manufacturing method for an optical system, and a manufacturing method for an optical element, which are capable of calibrating system errors in a short time and with high accuracy.

[0069] Although the 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 of the present invention. [Explanation of symbols]

[0070] 1. Wavefront measurement device 40 Half mirror (second reflecting part) 50 Relay optical system (optical system) 60 Half mirror (first reflecting part) 80 Wavefront sensor (light receiving part) 90 Computer (calculation section) 100 First light source system (first light source unit) 200 Second light source system (second light source unit)

Claims

1. a first light source unit that emits a first light toward the test object; an optical system that guides the first light that has passed through the object to be measured; a light receiving unit that receives the first light that has passed through the object and the optical system; a second light source unit that emits a second light; a first reflecting unit that is disposed between the optical system and the light receiving unit in an optical path of the first light and reflects the second light to the optical system; a second reflecting unit that is disposed between the first light source unit and the optical system in an optical path of the first light and reflects the second light to the light receiving unit; a calculation unit that calculates reference data based on a second signal output by the light receiving unit based on the second light, and calculates a wavefront of the test object based on a first signal output by the light receiving unit based on the first light and the reference data.

2. a third reflecting section that is disposed 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 to the light receiving section; 2. The wavefront measuring device according to claim 1, wherein the calculation section calculates the reference data based on a signal corresponding to the second light that has passed through the third reflecting section and is output from the light receiving section.

3. 3. The wavefront measuring device according to claim 1, wherein the light receiving section receives the second light having been transmitted through the first reflecting section.

4. a third light source unit that emits a third light; a fourth reflecting unit that is disposed between the optical system and the first reflecting unit in the optical path of the first light and reflects the third light to the light receiving unit, 4. The wavefront measuring device according to claim 1, wherein the calculation section calculates the reference data based on a signal corresponding to the third light output from the light receiving section.

5. 5. The wavefront measuring device according to claim 1, wherein the light receiving section has a microlens array.

6. 6. The wavefront measuring device according to claim 1, wherein the light receiving section has a Hartmann mask.

7. 7. The wavefront measuring device according to claim 1, wherein the light receiving unit is an image sensor.

8. 7. The wavefront measuring device according to claim 1, wherein the reference data is information regarding positions of a plurality of point images on the light receiving unit.

9. 9. The wavefront measuring device according to claim 1, wherein the first reflecting portion is detachable.

10. 10. The wavefront measuring apparatus according to claim 1, wherein the second light source unit is detachable.

11. a first light receiving step of receiving the first light emitted from the first light source unit by the light receiving unit via the test object and the optical system; a second light receiving step of receiving a second light emitted from a second light source unit and reflected by a first reflecting unit disposed between the optical system and the light receiving unit in an optical path of the first light and a second reflecting unit disposed between the first light source unit and the optical system in an optical path of the first light; a first calculation step of calculating reference data based on a signal corresponding to the second light output from the light receiving unit; a second calculation step of calculating a wavefront of the object based on a signal corresponding to the first light and the reference data.

12. Assembling an optical system; and evaluating optical performance of the assembled optical system by measuring a wavefront of the optical system using the wavefront measurement method according to claim 11.

13. Processing an optical element; and evaluating 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.

Images