Optical parameter detection system and method

Abstract

This application provides an optical parameter detection system for detecting the optical parameters of an objective lens under test, comprising: a wavefront sensor that transmits and receives test light; a light guiding assembly including a turntable and a deflector mirror disposed on the turntable; the turntable rotation drives the deflector mirror to rotate to reflect the test light to the objective lens under test at different angles, and to reflect the test light at the objective lens under test to the wavefront sensor at different angles; and a spherical mirror, the detection position of the objective lens under test being located between the light guiding assembly and the spherical mirror, the spherical mirror being located on the image side of the objective lens under test and movable along the optical axis of the objective lens under test, used to reflect the test light emitted from the objective lens under test back to the objective lens under test; the wavefront sensor detects the wavefront aberration of the objective lens under test in different fields of view based on the rotation angle of the turntable and obtains the optical parameters of the objective lens under test based on the wavefront aberration and the displacement of the spherical mirror. This application also provides an optical parameter detection method.

Description

Technical Field

[0001] This application relates to the field of optical parameter detection, and in particular to an optical parameter detection system and an optical parameter detection method applied to the optical parameter detection system. Background Technology

[0002] In different optical systems, it is usually necessary to select objectives with different optical parameters based on the structure and function of the optical system. The optical parameters of the objectives include, but are not limited to, wavefront aberration, field of view, vignetting, and chromatic aberration.

[0003] The optical parameters of the aforementioned objectives can typically be measured using different testing systems or methods. For example, wavefront aberration and field of view can be measured using the two-way transmission method; focal length can be measured using a focal length meter; distortion information can be measured using a distortion test chart (with a regular dot matrix pattern); numerical aperture can be measured using a numerical aperture meter; and field curvature information can be detected using a workpiece stage, etc.

[0004] On the one hand, different optical parameters require different instruments or methods for measurement, which is not conducive to improving the convenience of detection. On the other hand, the detection accuracy of the aforementioned detection systems is also relatively low. For example, when using a distortion test card to detect distortion information, the measurement error of distortion information cannot be further improved due to the symmetry of the dot matrix pattern and the dot matrix interval error of about 3μm; when using a workpiece stage to measure field curvature information, the test accuracy is limited to the micrometer level by the workpiece stage positioning error. Summary of the Invention

[0005] This application provides an optical parameter detection system for detecting the optical parameters of an objective lens under test, including:

[0006] A wavefront sensor, which transmits and receives test light;

[0007] A light guiding assembly, comprising a turntable and a deflecting mirror disposed on the turntable; the turntable rotates to rotate the deflecting mirror to reflect the test light at different angles to the objective lens under test, and to reflect the test light at the objective lens under test at different angles to the wavefront sensor; and

[0008] A spherical mirror is used to reflect the test light emitted from the objective lens. The detection position of the objective lens under test is located between the light guiding component and the spherical mirror. The spherical mirror is located on the image side of the objective lens under test and can move along the optical axis of the objective lens under test. The wavefront sensor detects the wavefront aberration of the objective lens under test in different fields of view based on the rotation angle of the turntable and obtains the optical parameters of the objective lens under test based on the wavefront aberration and the displacement of the spherical mirror.

[0009] This application also provides an optical parameter detection method, applied to the optical parameter detection system described above. The optical parameter detection method includes a field-of-view detection step, which comprises:

[0010] The reflector is moved to the confocal position of the objective lens under test, and the wavefront sensor of wave aberration emits test light;

[0011] The angle at which the test light is incident on the objective lens under test is changed multiple times by the light guiding component; and...

[0012] The wavefront sensor detects the wavefront aberration of the central field of view and the off-axis field of view of the objective lens under test, and determines the field of view of the objective lens under test based on the detection results of the wavefront aberration.

[0013] The aforementioned optical parameter detection system includes a wavefront sensor, a light guiding assembly, and a spherical mirror. The light guiding assembly includes a turntable and a deflector mirror mounted on the turntable. The spherical mirror is located on the image side of the objective lens under test and can move along the optical axis of the objective lens. The wavefront sensor can detect the wavefront aberration of the objective lens under test in different fields of view based on the rotation angle of the turntable, and obtain the optical parameters such as the field of view of the objective lens under test based on the wavefront aberration and the displacement of the spherical mirror. Therefore, the aforementioned optical parameter detection system can measure more than one optical parameter without changing the detection instrument when detecting different optical parameters, which improves the convenience of detection. Furthermore, the aforementioned optical parameter detection device has high accuracy. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the optical parameter detection system according to Embodiment 1 of this application.

[0015] Figure 2 This is a schematic flowchart illustrating the steps involved in detecting wavelet aberrations and field of view of an objective lens using the optical parameter detection system described in Embodiment 1 of this application.

[0016] Figure 3 This is a schematic diagram of the field of view of the second test light.

[0017] Figure 4 This is a flowchart illustrating the steps involved in detecting the numerical aperture and telecentricity of an objective lens using the optical parameter detection system described in Embodiment 1 of this application.

[0018] Figure 5 This is a flowchart illustrating the steps involved in detecting the distortion information and focal length of an objective lens using the optical parameter detection system described in Embodiment 1 of this application.

[0019] Figure 6 This is a flowchart illustrating the steps involved in detecting the field curvature of an objective lens using the optical parameter detection system described in Embodiment 1 of this application.

[0020] Figure 7 This is a schematic diagram of the optical parameter detection system according to Embodiment 2 of this application.

[0021] Figure 8 This is a schematic flowchart illustrating the steps involved in detecting the vertical and axial chromatic aberrations of an objective lens using the optical parameter detection system described in Embodiment 2 of this application.

[0022] Explanation of main component symbols

[0023] Optical parameter detection system 100, 200

[0024] Wavefront sensors 110, 210

[0025] Light exit end faces 111, 211

[0026] Plane standard mirrors 112 and 212

[0027] Light guiding components 120, 220

[0028] Turntables 121 and 221

[0029] Conversion mirrors 122 and 222

[0030] 130° and 230° spherical mirrors

[0031] Parallel flat plates 140, 240

[0032] Laser interferometer 150, 250

[0033] Spectrometers 16 and 26

[0034] Three-sided reflecting mirrors 161, 261

[0035] Beam-splitting mirror groups 162 and 262

[0036] First Light Source 270

[0037] Second light source 280

[0038] 300 objective lens to be tested

[0039] Optical axis 310

[0040] First end 320

[0041] Second end 330

[0042] Steps S11, S12, S13, S14, S15

[0043] S21, S22, S23, S31, S32,

[0044] S33, S34, S35, S41, S42,

[0045] S43, S44, S45, S51, S52,

[0046] S53, S61, S62, S63

[0047] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0048] Example 1

[0049] Please see Figure 1 In this embodiment, the optical parameter detection system 100 is used to detect the optical parameters of the objective lens 300 under test. In this embodiment, the objective lens 300 under test is an infinite conjugate objective lens. Furthermore, the objective lens 300 under test can be a non-immersion objective lens or an immersion objective lens.

[0050] The optical parameter detection system 100 includes a wavefront sensor 110, a light guiding component 120, and a spherical reflector 130.

[0051] The wavefront sensor 110 is a Fizeau interferometer based on two-beam interference. The wavefront sensor 110 includes a light source and a photodetector (not shown). A portion of the light emitted by the light source serves as a first test light, and the other portion serves as a second test light. The wavefront sensor 110 has a light-emitting end face 111 and also includes a plane standard mirror 112, which is disposed on the light-emitting end face 111. The wavefront sensor 110 emits the first test light, which exits from the light-emitting end face 111 and is transmitted through the plane standard mirror 112. The wavefront sensor 110 also emits the second test light, which is reflected by the plane standard mirror 112. The photodetector receives the second test light reflected by the plane standard mirror 112. In this embodiment, the light emitted by the light source is a laser with a wavelength of 632.8 nm. Of the light emitted by the light source, 96% is emitted as the first test light, and 4% is reflected by the plane standard mirror 112 as the second test light and then received by the photoelectric sensor.

[0052] When the objective lens 300 under test is placed in the optical parameter detection system 100, the light guiding component 120 is located between the wavefront sensor 110 and the objective lens 300 under test, and is used to receive the first test light emitted from the wavefront sensor 110 and to guide the first test light to the objective lens 300 under test.

[0053] In this embodiment, the light guiding assembly 120 includes a turntable 121 and a deflector 122 disposed on the turntable 121. The turntable 121 can rotate itself to drive the deflector 122 to rotate synchronously, that is, there is no relative displacement between the turntable 121 and the deflector 122. The deflector 122 is used to reflect the received light. In this embodiment, the deflector 122 is used to reflect the first test light emitted from the wavefront sensor 110 to the objective lens 300 under test. By controlling the turntable 121 to rotate at different angles, the deflector 122 can be controlled to rotate synchronously at different angles, thereby controlling the deflector 122 to incident the first test light onto the objective lens 300 under test at different angles, thereby detecting the field of view of the objective lens 300 under test.

[0054] The objective lens 300 under test has an optical axis 310. The angle between the first test light incident on the objective lens 300 and the optical axis 310 of the objective lens 300 is defined as the incident angle of the first test light.

[0055] The objective lens 300 under test has a first end 320 and a second end 330. The objective lens 300 under test is located between the light guiding assembly 120 and the spherical mirror 130, with the first end 320 close to the light guiding assembly 120 and the second end close to the spherical mirror 130.

[0056] In this embodiment, the spherical mirror 130 has a concave spherical surface for reflecting light. The spherical mirror 130 receives the first test light emitted from the second end 330 of the objective lens 300 under test, and after self-collimation, reflects the first test light as the first detection light back to the objective lens 300 under test. The first detection light emitted from the objective lens 300 under test is incident from the first end 320 to the light guiding assembly 120 and reflected by the light guiding assembly 120 to the photoelectric sensor in the wavefront sensor 110. The photoelectric sensor in the wavefront sensor 110 can detect the wavefront aberration of the objective lens 300 under test based on the received first detection light and second test light.

[0057] The spherical mirror 130 can be translated along the optical axis of the objective lens 300 under test. By translating the spherical mirror 130 along the optical axis of the objective lens 300 under test, the numerical aperture and telecentricity of the objective lens under test can be detected.

[0058] In this embodiment, the optical parameter detection system 100 further includes a parallel plate 140. The parallel plate 140 is located between the light guiding component 120 and the spherical mirror 130. When the objective lens 300 under test is located in the optical path of the optical parameter detection system 100, the parallel plate 14 is located between the light guiding component 120 and the objective lens 300 under test.

[0059] In this embodiment, the optical parameter detection system 100 also includes a laser interferometer rangefinder 150 and a beam splitter 16.

[0060] In this embodiment, the laser interferometric rangefinder 150 is used to emit a third test beam. The beam-splitting assembly 16 includes a three-sided mirror 161 and a beam-splitting mirror group 162. The three-sided mirror 161 includes a first reflecting surface, a second reflecting surface, and a third reflecting surface. The normal of the first reflecting surface is parallel to the optical axis of the objective lens 300 under test, and the normal of the second reflecting surface is parallel to the parallel plate 140. After the third test beam is emitted from the laser interferometric rangefinder 150, it is guided by the beam-splitting mirror group 162 to the first, second, and third reflecting surfaces of the three-sided mirror 161, respectively. It is then returned to the laser interferometric rangefinder from different directions by the first, second, and third reflecting surfaces. The three-sided mirror is fixed to the spherical mirror, so the laser interferometric rangefinder can obtain the displacement of the spherical mirror by measuring the displacement of the three-sided mirror. The optical path corresponding to the first reflecting surface is the field curvature test optical path of the objective lens 300 under test, the optical path corresponding to the second reflecting surface is the distortion and focal length test optical path of the objective lens 300 under test, and the optical path corresponding to the third reflecting surface is used to eliminate detection errors.

[0061] The third test light reflected by the first, second, and third reflecting surfaces is received by the laser interferometer 150 and used to detect the displacement information of the three-sided mirror 161 based on the reflected third test light. In this embodiment, the three-sided mirror and the spherical mirror 130 are fixedly connected by a mechanical structure, and the two can be synchronously displaced, that is, the displacement amount and displacement direction of the two remain the same. Therefore, the displacement information of the three-sided mirror obtained by the laser interferometer 150 is the displacement information of the spherical mirror 130 (including displacement direction and displacement distance). In other embodiments, the three-sided mirror and the spherical mirror 130 can be synchronously displaced in ways other than a fixed mechanical connection, for example, by driving the three-sided mirror and the spherical mirror 130 with the same driving signal by a driver to make the two synchronously displace.

[0062] The following describes the method and steps for the optical parameter detection system 100 to detect the optical parameters (wavelength aberration, field of view, numerical aperture, telecentrism, distortion, focal length, and field curvature) of the objective lens 300 under test.

[0063] (a) The optical parameter detection system 100 detects the wavelet aberration and field of view of the objective lens 300 under test:

[0064] Please see Figure 2 Methods for detecting wavefront aberration and field of view of objective lens 300 include:

[0065] Step S11: Move the spherical mirror to the confocal position of the objective lens under test, and the wavefront sensor of wave aberration emits test light;

[0066] Step S12, the angle at which the test light is incident on the objective lens under test is changed multiple times using the light guiding component; and,

[0067] Step S13: The wavefront sensor detects the wavefront aberration of the central field of view and the off-axis field of view of the objective lens under test, and determines the field of view of the objective lens under test based on the detection result of the wavefront aberration.

[0068] In step S11, the spherical mirror 130 is moved to the confocal position of the objective lens 300 under test; the relative position of the parallel plate 140 and the objective lens 300 under test in the optical parameter detection system 100 is adjusted so that the parallel plate 140 is parallel to the first end 320 of the objective lens 300 under test, that is, perpendicular to the optical axis 310 of the objective lens 300 under test; the wavefront sensor 110 is turned on so that the wavefront sensor 110 emits the first test light and the second test light.

[0069] The second test light is reflected back to the photodetector of the wavefront sensor 110 by the plane standard mirror 112. The first test light is guided by the light guiding assembly 120 to the objective lens 300 under test and enters the spherical mirror 130 from the second end 330 of the objective lens 300. After being collimated by the spherical mirror 130, it returns to the objective lens 300 under test and exits from the objective lens 300 to the light guiding assembly 120, where it is guided to the wavefront sensor 110. The second test light and the first test light, after passing through the objective lens 300 twice, undergo two-beam interference on the photodetector of the wavefront sensor 110, producing an interference fringe image.

[0070] Initially, the placement angle of the folding mirror 122 ensures that the first test light is incident on the objective lens 300 parallel to its optical axis 310. The angle of the folding mirror 122 at this moment is defined as the initial angle. The wavefront aberration measured at this moment is the central field-of-view wavefront aberration of the objective lens 300.

[0071] In step S12, after measuring the wavefront aberration of the central field of view, the turntable 121 is controlled to rotate the conversion mirror 122 by a preset angle. This preset angle changes the incident angle of the first test light onto the objective lens 300 under test, allowing the wavefront aberration of the objective lens 300 in the off-axis field of view to be detected at this angle. In step S13, the field of view of the objective lens 300 under test is determined based on the detection result of the wavefront aberration.

[0072] Please see Figure 3The field of view of the objective lens 300 under test includes a central field of view 340, an off-axis field of view 350, and an edge field of view 360 arranged sequentially from the center to the edge. In this embodiment, the wavefront aberration of the objective lens 300 under test in the central field of view 340 and the off-axis field of view 350 is detected. In this embodiment, by repeatedly increasing the angle α of the conversion mirror 122 outward from the central field of view 340, the values ​​of multiple wavefront aberrations can be detected in the off-axis field of view 350. In step S16, after each increase of the angle α, it is determined whether the edge field of view 360 has been reached. If it is determined in step S16 that the edge field of view 360 has not been reached, the angle α is increased further; if it is determined that the edge field of view 360 has been reached, the detection ends.

[0073] Since the second test light passes through the objective lens 300 twice, the detection result obtained by the wavefront sensor 110 corresponds to twice the actual wavefront aberration of the objective lens 300. The surface shape errors of the plane standard mirror 112, the convoluted mirror 122, and the spherical mirror 130 of the wavefront sensor 110 are much smaller than the actual wavefront aberration values ​​detected by the wavefront sensor 110; therefore, these errors can be ignored in the test results.

[0074] By repeatedly changing the angle of the conversion mirror 122, the field of view of the second test light is changed. The range of field of view that meets the wavelet aberration technical specifications is the field of view of the objective lens 300 under test.

[0075] (II) The optical parameter detection system 100 detects the vignetting information of the objective lens 300 under test:

[0076] Based on the aforementioned wavefront aberration detection results, an XY coordinate system can be established, defining the number of pixels along the X-axis of the central field of view as Px0 and the number of pixels along the Y-axis as Py0. The number of pixels along the X-axis of the off-axis field of view is defined as Px, and the number of pixels along the Y-axis as Py. Then, the corresponding vignetting coefficient in the X-direction of the off-axis field of view is... The vignetting coefficient in the Y direction is The vignetting coefficients mentioned above represent the vignetting information for the objective lens 300 under test.

[0077] (III) The optical parameter detection system 100 detects the numerical aperture and telecentricity of the objective lens 300 under test:

[0078] Please see Figure 4 Methods for detecting the numerical aperture and telecentricity of the objective lens 300 under test include:

[0079] Step S21: Under the same field of view as in the field of view detection step, move the spherical mirror from the confocal position to the defocal position along the optical axis, with a moving distance of Δr1.

[0080] Step S22: Record the current wavefront aberration, and obtain the peak-to-peak value ε of the wavefront aberration based on the current wavefront aberration and the wavefront aberration in the field detection step under the same field of view.OPD ;

[0081] Step S23, based on the peak-to-peak value ε of the wave aberration OPD Calculate the numerical aperture of the objective lens under test, and calculate the telecentricity based on the displacement of the spherical mirror and the number of interference fringes.

[0082] In this embodiment, the spherical mirror 130 has an initial position, at which point the spherical mirror 130 and the objective lens 300 under test are confocal. In step S21, the spherical mirror 130 is controlled to move multiple times along the optical axis 310 of the objective lens 300 from this initial position, ensuring that the spherical mirror 130 does not shift in the direction perpendicular to the optical axis 310 during this process. In step S22, the detected wavefront aberration and the peak-to-peak wavefront aberration ε are recorded. OPD .

[0083] Define the object-space refractive index of the objective lens 300 under test as n, and the maximum incident light angle as θ. In step S23, the numerical aperture NA of the objective lens 300 under test is calculated based on the following formula:

[0084]

[0085] The displacement of the spherical mirror 130 from its initial position after each movement is defined as Δr1; the f-number of the objective lens under test is defined as f#, which is the ratio of the objective lens focal length f to the entrance pupil diameter D (f / D); the test wavelength of the wavefront sensor is defined as λ; and the number N of the tilted fringes of the concentric interference fringes generated by the spherical mirror 130 at position Δr1 is defined as N. Tilt Calculate the eccentricity of the center of the concave spherical reflecting surface of the objective lens 300 under test, i.e., the telecentrism τ of the principal ray in this field of view:

[0086]

[0087] (iv) The optical parameter detection system 100 detects the distortion information and focal length of the objective lens 300 under test:

[0088] Please see Figure 5 Methods for detecting the distortion information and focal length of the objective lens 300 under test include:

[0089] Step S31: Adjust the three-sided mirror so that the normal direction of the first reflecting surface is parallel to the optical axis of the objective lens under test, and the normal of the second reflecting surface is parallel to the parallel plate.

[0090] Step S32: Move the spherical mirror to the off-axis field of view, detect the displacement of the spherical mirror based on the optical path corresponding to the second reflecting surface, rotate the turning mirror to zero-fringe interference and record the rotation angle of the turntable;

[0091] Step S33: Obtain the focal length of the objective lens under test by linear fitting based on the displacement and the rotation angle, and obtain the distortion information of the objective lens under test based on the fitting residual of the field of view under different rotation angles.

[0092] In step S32, the angle of the conversion mirror 122 is changed using the high-precision turntable 121, thereby changing the field of view of the first test light. The test light, guided to the spherical mirror 130 by the second reflecting surface, is used to detect the position of the spherical mirror 130 in the field of view, that is, to detect the displacement relative to the initial position of the spherical mirror 130. In this embodiment, the initial position is defined as the position where the spherical mirror 130 and the objective lens 300 under test are cofocal. In step S32, the rotation angle α of the conversion mirror 122 is the angle of rotation relative to the initial angle. In this embodiment, the initial angle of the conversion mirror 122 is the angle at which the first test light is parallel to the optical axis 310 of the objective lens 300 under test.

[0093] In step S332, after each movement of the spherical mirror 130 and the rotating deflector 122, it is determined whether the current spherical mirror 130 has reached the edge of the field of view. If the determination is no, the spherical mirror 130 and the rotating deflector 122 continue to be moved, that is, steps S32 and S33 are repeated until the edge of the field of view is reached.

[0094] Ideally, the relationship between the image-side test light angle β and the object-side field of view h and focal length f is f tanβ = h. In step S33, this formula is used to fit the measured object-side field of view heights and corresponding image-side collimating light angles. The f obtained by linear fitting is the actual focal length of the objective lens, and the fitting residual for each field of view is the distortion of the corresponding field of view.

[0095] (v) The optical parameter detection system 100 detects the field curvature information of the objective lens 300 under test:

[0096] Please see Figure 6 Methods for detecting the field curvature information of the objective lens 300 under test include:

[0097] Step S41: Adjust the spherical mirror and the light guiding assembly so that the normal direction of the spherical mirror is parallel to the optical axis direction of the objective lens under test.

[0098] Step S42: Move the spherical mirror to the off-axis field of view and rotate the deflector to zero fringes;

[0099] Step S43: Record the displacement Δr2 of the spherical mirror detected by the laser interferometer.

[0100] Step S44: Determine whether the spherical mirror has reached the edge field of view of the objective lens under test at this time;

[0101] If the determination is negative, repeat steps S42 and S43; if the determination is positive, execute step S45: calculate the field curvature information of the objective lens under test based on the displacement Δr2 recorded by the laser interferometer.

[0102] The test values ​​(displacement Δr2) obtained by the test light guided by the first reflective surface are recorded under different fields of view. The displacement Δr2 detected by the test light guided by the reflective surface under each field of view is linearly fitted, and the remaining nonlinear term is the field curve of the corresponding field of view.

[0103] The optical parameter detection system 100 in this embodiment includes a wavefront sensor 110, a light guiding assembly 120, and a spherical mirror 130. The light guiding assembly 120 includes a turntable 121 and a deflector 122 disposed on the turntable 121. The spherical mirror 130 is located on the image side of the objective lens 300 under test and can move along the optical axis 310 of the objective lens 300. The wavefront sensor 110 can detect the wavefront aberration of the objective lens 300 under different fields of view based on the rotation angle of the turntable 121, and obtain the optical parameters such as the field of view of the objective lens 300 under test based on the wavefront aberration and the displacement of the spherical mirror 130. Therefore, the optical parameter detection system 100 can measure more than one optical parameter without changing the detection instrument when detecting different optical parameters, which is beneficial to improving the convenience of detection. Moreover, the optical parameter detection device has high accuracy.

[0104] Example 2

[0105] Please see Figure 7 The optical parameter detection system 200 in this embodiment has a structure and function that are basically the same as the optical parameter detection system 100 in Embodiment 1. The optical parameter detection system 200 can also be used to detect optical parameters such as wavefront aberration, field of view, numerical aperture, telecentrism, distortion information, focal length, and field curvature information of the objective lens 300 under test described in Embodiment 1, and the detection methods of the above optical parameters are also basically the same as those in Embodiment 1.

[0106] The main difference between the optical parameter detection system 200 and the optical parameter detection system 100 is that the wavefront sensor 210 of the optical parameter detection system 200 is a Shaker-Hartmann sensor, and the optical parameter detection system 200 also includes a first light source 270 and a second light source 280 that emit light in a time-division manner. The optical parameter detection system 200 can be used to detect the chromatic aberration of the objective lens 300 under test. The following only describes the differences from the optical parameter detection system 100 in Embodiment 1.

[0107] In this embodiment, both the first light source 270 and the second light source 280 are laser light sources. The first light source 270 and the second light source 280 are used to emit lasers of different wavelengths as test lights in a time-division manner. The laser emitted by the first light source 270 is defined as the fourth test light, and the laser emitted by the second light source 280 is defined as the fifth test light.

[0108] The fourth and fifth test lights are incident on the wavefront sensor 210 and emitted from the light-emitting end face 211 to the light guiding assembly 220. The light guiding assembly 220 reflects the fourth and fifth test lights to the objective lens 300 under test. The spherical mirror 230 receives the fourth and fifth test lights emitted from the objective lens 300 under test and reflects the fourth test light as the second detection light and the fifth test light as the third detection light. The wavefront sensor 210 is also used to detect the chromatic aberration of the objective lens 300 under test based on the second detection light, the third detection light, and the second test light.

[0109] In this embodiment, the optical parameter detection system 200, compared to the optical parameter detection system 100, can also be used to detect the chromatic aberration of the objective lens 300 under test: transverse chromatic aberration and axial chromatic aberration. The following will describe the method and steps for the optical parameter detection system 200 to detect the chromatic aberration of the objective lens 300 under test.

[0110] The chromatic aberration of the objective lens 300 under test includes transverse chromatic aberration and axial chromatic aberration.

[0111] Please see Figure 8 Methods for detecting the transverse and axial chromatic aberration of the objective lens 300 under test include:

[0112] Step S51: Control the first light source and the second light source to emit fourth and fifth test lights with different wavelengths in a time-division manner;

[0113] Step S52, the wavefront sensor performs background calibration and system error calibration;

[0114] Step S53: When the image-side field of view is the same, perform the distortion and focal length detection steps, and control the laser interferometer to record the deviation of the object height when outputting different test lights;

[0115] Step S54: The maximum value of the deviation of the object height of all image-side field angles is taken as the transverse chromatic aberration of the objective lens under test.

[0116] In step S55, when the image-side field of view is the same, the control ranging system records the detection values ​​corresponding to the above field curvature detection steps S41-S45 when different test lights are output. The maximum deviation value of the detection values ​​in the field curvature detection steps is taken as the axial chromatic aberration of the objective lens under test.

[0117] In step S51, the first light source 270 is controlled to emit the fourth test light during the first time period, and the second light source 280 is controlled to emit the fifth test light during the second time period. The fourth and fifth test lights are lasers with different wavelengths. In step S53, the image-side field of view is kept unchanged during the first and second time periods, and the laser interferometric rangefinder 150 is controlled to record the deviation of the object height measured in the first and second time periods, respectively.

[0118] In step S55, the image-side field of view remains unchanged in the first and second time periods. Based on this, the laser interferometer 150 is controlled to record the detection values ​​corresponding to the field curvature detection steps S41-S45 when different test lights (fourth test light and fifth test light) are output. The maximum deviation value of the detection value of the field curvature detection step is used as the axial chromatic difference in the direction of the optical axis 310 of the objective lens 300 under test.

[0119] The optical parameter detection system 200 in this embodiment can achieve all the beneficial effects of the optical parameter detection system 100 described in Embodiment 1. Furthermore, by improving the wavefront sensor 110 to a Shaker-Hartmann sensor and adding a first light source 270 and a second light source 280, it is also possible to detect the chromatic aberration (including transverse chromatic aberration and axial chromatic aberration) of the objective lens 300 under test.

[0120] Those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of protection claimed in this application.

Claims

1. An optical parameter detection system for detecting the optical parameters of an objective lens under test, characterized in that, include: A wavefront sensor, which transmits and receives test light; A light guiding assembly includes a turntable and a deflection mirror disposed on the turntable; the turntable rotates to drive the deflection mirror to rotate so as to reflect the test light to the objective lens under test at different angles, and to reflect the test light at the objective lens under test to the wavefront sensor at different angles. A spherical mirror is used to reflect the test light emitted from the objective lens. The detection position of the objective lens under test is located between the light guiding component and the spherical mirror. The spherical mirror is located on the image side of the objective lens under test and can move along the optical axis of the objective lens under test. The wavefront sensor detects the wavefront aberration of the objective lens under test under different fields of view based on the rotation angle of the turntable, and obtains the field of view, vignetting information and numerical aperture of the objective lens under test based on the wavefront aberration. The telecentrism of the objective lens under test is obtained based on the wavefront aberration and the displacement of the spherical mirror. A parallel plate is positioned on the side of the objective lens to be tested away from the spherical mirror and perpendicular to the optical axis; A laser interferometer is mounted on one side of the spherical mirror and located outside the optical axis of the objective lens under test. as well as A three-sided mirror is located between the laser interferometer and the spherical mirror, and the three-sided mirror and the spherical mirror can be moved synchronously. The laser interferometer is used to measure the position of the three-sided mirror. The three-sided mirror includes a first reflecting surface, a second reflecting surface, and a third reflecting surface that are perpendicular to each other. The normal of the first reflecting surface is parallel to the optical axis of the objective lens under test, and the normal of the second reflecting surface is parallel to the parallel plate. The detection light emitted by the laser interferometer is split and reflected, and then transmitted to the spherical mirror through different reflecting surfaces of the three-sided mirror. The optical path corresponding to the first reflecting surface is the field curvature test optical path of the objective lens under test, and the optical path corresponding to the second reflecting surface is the distortion and focal length test optical path of the objective lens under test.

2. The optical parameter detection system as described in claim 1, characterized in that, The wavefront sensor is a Fizeau interferometer based on two-beam interference; or, the wavefront sensor includes a Shaker-Hartmann sensor and a light source used in conjunction with the Shaker-Hartmann sensor.

3. The optical parameter detection system as described in claim 2, characterized in that, The light source is used to generate test light of different wavelengths. The Shaker-Hartmann sensor obtains the transverse chromatic aberration of the objective lens under test based on the test result deviation corresponding to the test light of different wavelengths. The laser interferometer obtains the axial chromatic aberration of the objective lens under test based on the position of the spherical mirror detected under different test lights.

4. A method for detecting optical parameters, characterized in that, Applied to the optical parameter detection system as described in any one of claims 1-3, the optical parameter detection method includes a field-of-view detection step, the field-of-view detection step including: Move the spherical mirror to the confocal position of the objective lens under test, and the wavefront sensor of wave aberration emits test light; The angle at which the test light is incident on the objective lens under test is changed multiple times by the light guiding component; and... The wavefront sensor detects the wavefront aberration of the central field of view and the off-axis field of view of the objective lens under test, and determines the field of view of the objective lens under test based on the detection results of the wavefront aberration. The optical parameter detection method further includes a vignetting information detection step, a numerical aperture detection step, and a telecentricity detection step; in the vignetting information detection step and the numerical aperture detection step, the vignetting information and numerical aperture of the objective lens under test are obtained based on the wavefront aberration; in the telecentricity detection step, the telecentricity of the objective lens under test is obtained based on the wavefront aberration and the displacement of the spherical mirror along the optical axis of the objective lens under test. The optical parameter detection method further includes distortion and focal length detection steps, which include: Adjust the three-sided reflecting mirror so that the normal direction of the first reflecting surface is parallel to the optical axis of the objective lens under test, and the normal of the second reflecting surface is parallel to the parallel plate. Move the spherical mirror to an off-axis field of view, detect the displacement of the spherical mirror based on the optical path corresponding to the second reflecting surface, rotate the turning mirror to zero-fringe interference and record the rotation angle of the turntable; The focal length of the objective lens under test is obtained by linear fitting of the displacement and the rotation angle, and the distortion information of the objective lens under test is obtained by fitting the field of view residuals under different rotation angles. The optical parameter detection method also includes a field curvature detection step: Record the detection value corresponding to the optical path of the first reflective surface, perform linear fitting on the detection value, and obtain the field curvature information of the objective lens under test based on the fitting residual.

5. The optical parameter detection method as described in claim 4, characterized in that, The vignetting information detection steps include: The vignetting coefficient of the off-axis field of view of the objective lens under test is obtained based on the wavefront aberration between the central field of view and the off-axis field of view. The vignetting coefficient of the off-axis field of view of the objective lens under test in the X direction is: The vignetting coefficient in the Y direction is Where Px0 is the number of pixels on the X-axis of the central field of view, Py0 is the number of pixels on the Y-axis of the central field of view, Px is the number of pixels on the X-axis of the off-axis field of view, and Py is the number of pixels on the Y-axis.

6. The optical parameter detection method as described in claim 4, characterized in that, The numerical aperture detection step includes: In the same field of view as in the field-of-view detection step, the spherical mirror is moved from the confocal position to the defocal position along the optical axis by a distance Δr1. The current wavefront aberration is recorded, and the peak-to-peak value of the wavefront aberration is obtained based on the current wavefront aberration and the wavefront aberration in the same field of view detection step. The numerical aperture NA of the objective lens under test is obtained according to the following formula: Wherein, n is the refractive index of the object space of the objective lens under test.

7. The optical parameter detection method as described in claim 6, characterized in that, The wavefront sensor includes a Shaker-Hartmann sensor and a light source used in conjunction with the Shaker-Hartmann sensor, the light source being used to generate the test light of different wavelengths; The optical parameter detection method further includes: Control the light source to emit test light of different wavelengths at different times. The Shaker-Hartmann sensor is subjected to background calibration and system error calibration; When the field of view is the same, perform the distortion and focal length detection steps and control the laser interferometer to record the deviation of the object height when outputting different test lights; The maximum deviation of the object height at all image-side field angles is taken as the transverse chromatic aberration of the objective lens under test. With the same image-side field of view, the control ranging system records the detection values ​​corresponding to the field curvature detection step when outputting different test lights. The maximum deviation of the detection values ​​in the field curvature detection step is taken as the axial chromatic aberration of the objective lens under test.

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