Wave aberration detection device

Abstract

The invention relates to a wave aberration detection device, which comprises a light source, a hole array plate and a wavefront detection module, and is characterized in that the light source is used for outputting incoherent light; the hole array plate is arranged between the light source and the to-be-detected lens, and the hole array plate is provided with a plurality of light holes; the wavefront detection module is used for detecting wave aberration information of the lens to be detected; light output by the light source can be received by the wavefront detection module after passing through the light hole and the lens to be detected, and interference information is generated. The wave aberration detection device provided by the invention is suitable for detecting the wave aberration of the to-be-detected lens in an incoherent light source scene.

Description

Technical Field

[0001] This application relates to the technical field of optical inspection, specifically to a wavefront aberration detection device. Background Technology

[0002] In devices using high-precision lenses, such as high-precision lithography machines, the lens's wavefront aberration changes with environmental variations. Online feedback of wavefront aberration plays a crucial role in maintaining high-precision imaging in lithography machines. For lithography applications, because lithography itself requires incoherent illumination to mitigate standing wave effects, it is difficult to find an ideal, highly coherent light source for the operating wavelength of the lens under inspection, thus lacking the necessary coherent illumination. This renders traditional inspection techniques ineffective. Summary of the Invention

[0003] This application provides a wavelet aberration detection device, including: A light source used to output incoherent light; A hole array plate is disposed between the light source and the lens under test, and the hole array plate is provided with multiple light-transmitting holes; The wavefront detection module is used to detect the wavefront aberration information of the lens under test; The light emitted by the light source passes through the light-transmitting hole and the lens under test, and can be received by the wavefront detection module to generate interference information.

[0004] According to one embodiment of this application, the wavefront detection module is movable relative to the aperture array plate to receive light transmitted through different apertures and generate corresponding interference information. The plane on which the wavefront detection module moves is parallel to the plane on which the aperture array plate is located.

[0005] According to one embodiment of this application, the spacing between adjacent light-transmitting holes is adapted to the light-receiving range of the wavefront detection module. When the wavefront detection module receives the image formed by one of the light-transmitting holes, the images formed by the other light-transmitting holes are located outside the light-receiving range of the wavefront detection module.

[0006] According to one embodiment of this application, the wavefront detection module can move relative to the aperture array plate to detect the movement trajectory of the feature spot in the interference information corresponding to a single aperture, and obtain the wavefront aberration of the field of view corresponding to the aperture based on the movement trajectory.

[0007] According to one embodiment of this application, the wavefront detection module includes a phase plate, which is used to receive light transmitted through the lens under test and generate four-wave shearing interference.

[0008] According to one embodiment of this application, the light output from the light source passes through the aperture array plate and the lens under test to form an aperture array image, and the phase plate is closer to the lens under test than the aperture array image.

[0009] According to one embodiment of this application, the spacing between the aperture array plate and the aperture array image is 50μm-1000μm.

[0010] According to one embodiment of this application, the wavefront detection module includes a phase plate, an aspherical lens, and a photosensitive unit arranged sequentially along the light propagation path.

[0011] According to one embodiment of this application, the phase plate includes multiple phase modulation regions, including a first phase modulation region and a second phase modulation region. The phase difference generated by the light transmitted through the lens under test through the first phase modulation region and the second phase modulation region is π. The first phase modulation region and the second phase modulation region are arranged in a periodic alternation.

[0012] According to one embodiment of this application, the edge of the phase modulation region is provided with a blocking frame, the width of which is half the side length of the phase modulation region.

[0013] The wavefront aberration detection device provided in this application, by setting an aperture array plate, allows the incoherent light output from the light source to be received by the wavefront detection module through the light transmission aperture, and is suitable for detecting the wavefront aberration of the lens under test in incoherent light source scenes. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the structure of an embodiment of the wavelet aberration detection device of this application; Figure 2 yes Figure 1 A schematic diagram of the wavefront detection module of the wavefront aberration detection device shown in the figure. Figure 3 This is a partial structural schematic diagram of an embodiment of the phase plate of this application; Figure 4 This is a schematic flowchart of an embodiment of the wavelet aberration detection method of this application; Figure 5 yes Figure 4 The flowchart of step S100 of the wavelet aberration detection method shown is a schematic diagram of an embodiment. Figure 6 yes Figure 4 The flowchart of step S200 of the wavelet aberration detection method shown is a schematic diagram of an embodiment. Figure 7 yes Figure 4 The flowchart of step S210 of the wavelet aberration detection method shown is a schematic diagram of an embodiment. Figure 8 yes Figure 4 The flowchart of an embodiment of the wavelet aberration detection method shown is as follows: Step S211; Figure 9 It is an interferogram of wavefront detection for measuring primary aberrations; Figure 10 It is the interferogram corresponding to defocus in primary aberrations; Figure 11 It is an interferogram of astigmatism in primary aberrations, taking horizontal and vertical astigmatism as an example; Figure 12 It is an interferogram of coma, taking lateral coma as an example, in primary aberrations; Figure 13 It is the interferogram corresponding to spherical aberration in primary aberrations; Figure 14 This is a schematic diagram of wavefront distribution calculated based on horizontal and vertical contour grids; Figure 15 This is a schematic diagram illustrating the steps of one embodiment of the manufacturing method of this application; Figure 16 This is a flowchart illustrating an embodiment of the manufacturing method of this application; Figure 17 yes Figure 16 A flowchart illustrating an embodiment of step S400 of the manufacturing method shown; Figure 18 yes Figure 16 A flowchart illustrating an embodiment of step S410 of the manufacturing method shown; Figure 19 yes Figure 16 The flowchart of step S500 of the manufacturing method shown is a schematic diagram of an embodiment.

[0016] The attached diagram lists the components represented by each number as follows: Wavelength aberration detection device 10, light source 110, aperture array plate 120, light-transmitting aperture 1201, aperture array image 1202, lens under test 130, spacing distance z, focal length f, object-side focal length f a Image focal length f bWavefront detection module 140, phase plate 141, aspherical lens 142, photosensitive unit 143, phase modulation area 145, first phase modulation area 1451, second phase modulation area 1452, shielding frame 146, substrate 200, groove 201, protrusion 210, first adhesive block 220, shielding layer 230, second adhesive block 240, edge 250. Detailed Implementation

[0017] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the application. Similarly, the following embodiments are only some, not all, embodiments of the present application, and all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present application.

[0018] The terms "first," "second," and "third" used in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movement of components in a specific posture (as shown in the figures). If the specific posture changes, the directional indication will also change accordingly. The terms "comprising" and "having," and any variations thereof, in the embodiments of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to these processes, methods, products, or devices.

[0019] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0020] This application provides a wavelet aberration detection device 10, such as... Figure 1As shown, the wavefront aberration detection device 10 includes a light source 110, an aperture array plate 120, and a wavefront detection module 140. The light source 110 is used to output incoherent light; the aperture array plate 120 is disposed between the light source 110 and the lens under test 130, and the aperture array plate 120 has multiple light-transmitting holes 1201; the wavefront detection module 140 is used to detect the wavefront aberration information of the lens under test 130; wherein, the light output by the light source 110 can be received by the wavefront detection module 140 after passing through the light-transmitting holes 1201 and the lens under test 130. By setting the aperture array plate 120, the incoherent light output by the light source 110 can form approximately coherent light through the light-transmitting holes 1201, so that it can be received by the wavefront detection module 140 and generate interference information, which is suitable for detecting the wavefront aberration of the lens under test 130 in an incoherent light source scene.

[0021] Ultra-precision machining of optical surfaces has important applications in semiconductor lithography, super-resolution microscopy, and astronomical observation. Currently, the main methods for achieving ultra-precision machining are magnetorheological polishing and ion beam polishing. However, the equipment used for these two methods currently only has mechanical surface shape feedback devices, whose surface shape detection accuracy is limited to the micrometer level, which is insufficient for nanometer-level surface machining requirements. Therefore, the machined surface needs to be transported to an interferometer for inspection midway through processing; if insufficient machining is found, it is returned to the machining equipment for further processing. This frequent back-and-forth movement severely impacts lens processing efficiency; furthermore, the untimely feedback from high-precision inspection leads to over-processing and workpiece scrap. Furthermore, in devices using these high-precision lenses, such as high-precision lithography machines, the wavefront aberration of the lens changes with environmental variations. Therefore, online wavefront aberration feedback also plays a crucial role in maintaining high-precision imaging in lithography machines.

[0022] To achieve highly integrated high-precision measurement devices for in-situ measurements, it's crucial to avoid using bulky, traditional interferometric optical paths and high-precision reference mirrors. Furthermore, the reference optical path and the measurement wavefront optical path are often not shared, causing the phase difference of their interference to be affected by the surrounding environment, such as airflow and temperature differences. The Shark-Hartmann method uses microlens arrays to achieve integrated wavefront measurement; however, the microlenses themselves are extremely precise, and their size is difficult to miniaturize, often resulting in insufficient spatial resolution and inability to detect high-order Zernike terms in wavelet aberrations. The Ronchi shearing interferometry technique suffers from low average transmittance in its grating and checkerboard design, leading to a significant loss of incident light intensity and affecting the final signal-to-noise ratio. Four-wave shearing interferometry utilizes a high-transmittance, inverted checkerboard to split the incident wavefront into four parts and achieve a small spatial misalignment, resulting in a high signal-to-noise ratio interferometric image and a shared self-interfering optical path. This technique uses a coherent light source and leverages the Talbot effect, acquiring a long-distance self-image of the checkerboard through a photosensitive screen to reconstruct wavefront information. However, for photolithography applications, since photolithography itself requires incoherent illumination to alleviate the standing wave effect, it is difficult to find an ideal highly coherent light source for the working wavelength of the lens to be tested (such as the i-line in the ultraviolet light), thus lacking the conditions for coherent illumination. In this way, the traditional four-wave shearing interferometry technique is difficult to play a role.

[0023] The wavefront aberration detection device 10 in this application, by setting an aperture array plate 120, allows incoherent light to form approximately coherent light through the light transmission aperture 1201, making it suitable for various interferometric imaging techniques. When incoherent light emitted from the light source 110 passes through the light transmission aperture 1201, the light transmission aperture 1201 acts as a spatial filter. The light transmission aperture 1201 blocks the light emitted from most areas of the light source 110, allowing only the energy of a very small, even near-point-like area on the light source 110 to pass through. This light source area passing through the light source 110 can be regarded as a new, equivalent "point light source." Due to its extremely small spatial scale, the light waves emitted by this newly formed "point light source" exhibit high correlation at various points on its wavefront as they propagate forward. By setting the aperture array plate 120, the wavefront aberration detection device 10 avoids dependence on coherent light sources, facilitating in-situ measurements and improving measurement accuracy and efficiency.

[0024] In some embodiments, the light output by the light source 110 may also be coherent light.

[0025] In some embodiments, the size of the light-transmitting aperture 1201 is small enough to function as a spatial filter. However, the size of the light-transmitting aperture 1201 cannot be too small to avoid significant attenuation of light intensity.

[0026] In some embodiments, the wavefront detection module 140 can move relative to the aperture array plate 120 to receive light transmitted through different apertures 1201 and generate corresponding interference information.

[0027] In some embodiments, the plane on which the movement path of the wavefront detection module 140 is located is parallel to the plane on which the aperture array plate 120 is located.

[0028] In some embodiments, the light output from the light source 110 passes through the aperture array plate 120 and the lens under test 130 to form an aperture array image 1202. The plane containing the aperture array image 1202 is parallel to the aperture array plate 120. The aperture array plate 120 is located at the focal length f of the lens under test 130, that is, the aperture array plate 120 is located at the focal plane of the lens under test 130. The aperture array image 1202 is located on the side of the lens under test 130 away from the aperture array plate 120, and the aperture array image 1202 is located at the focal plane of the lens under test 130. The aperture array image 1202 includes multiple aperture images corresponding to multiple light-transmitting holes 1201. The wavefront detection module 140 can move along the plane containing the aperture array image 1202 to sequentially receive different aperture images.

[0029] In some embodiments, the spacing between adjacent light-transmitting holes 1201 is adapted to the light-receiving range of the wavefront detection module 140. When the wavefront detection module 140 receives the image formed by one of the light-transmitting holes 1201, the images formed by the other light-transmitting holes 1201 are located outside the light-receiving range of the wavefront detection module 140. Only after the image formed by the detected light-transmitting hole 1201 moves out of the light-receiving range can the images formed by the other light-transmitting holes 1201 enter the light-receiving range.

[0030] In some embodiments, the spacing between adjacent light-transmitting holes 1201 is greater than or equal to the diameter of the light-receiving range of the wavefront detection module 140.

[0031] In some embodiments, such as Figure 2 As shown, the wavefront detection module 140 includes a phase plate 141, which is used to receive the light transmitted through the lens 130 under test and generate four-wave shearing interference.

[0032] In some embodiments, the interference information corresponding to a single light-transmitting aperture 1201 includes an interference pattern formed by four-wave shearing interference. The interference pattern includes multiple feature spots, which are generated by four-wave interference. These feature spots may exhibit specific shapes such as a single maxima circular spot, a square back-shaped spot, or a cross-shaped spot as the interval distance z changes. These are collectively referred to as feature spots.

[0033] In some embodiments, the wavefront detection module 140 can move relative to the aperture array plate 120 to detect the movement trajectory of the feature spot in the interference information corresponding to a single aperture 1201. When the wavefront detection module 140 moves relative to a single aperture 1201, the position of the symmetry center of the feature spot in the interference pattern also moves accordingly, forming a movement trajectory. Based on the movement trajectory, the higher spatial resolution wavefront aberration of the field of view corresponding to the aperture 1201 can be obtained.

[0034] In some embodiments, such as Figure 3 As shown, the phase plate 141 includes multiple phase modulation regions 145, and the phase modulation region 145 includes a first phase modulation region 1451 and a second phase modulation region 1452. The phase difference generated by the light transmitted through the lens 130 under test through the first phase modulation region 1451 and the second phase modulation region 1452 is π.

[0035] In some embodiments, the first phase modulation region 1451 and the second phase modulation region 1452 are arranged in a periodic alternation.

[0036] In some embodiments, the first phase modulation region 1451 and the second phase modulation region 1452 are both square in shape, and the first phase modulation region 1451 and the second phase modulation region 1452 are arranged in a checkerboard pattern in a periodic alternation.

[0037] In some embodiments, the edge of the phase modulation region 145 is provided with a blocking frame 146, the width of which is half the side length of the phase modulation region 145. The width of the blocking frame 146 is equal to the distance between adjacent first phase modulation regions 1451 and second phase modulation regions 1452.

[0038] In some embodiments, the side length of the first phase modulation region 1451 is the same as the side length of the second phase modulation region 1452. Along the transverse or longitudinal direction of the phase plate 141, that is, along the extension direction of one side length of the phase modulation region 145, the first phase modulation region 1451, the blocking frame 146, the second phase modulation region 1452, and the blocking frame 146 are arranged in sequence to form a cycle, and the width of the blocking frame 146 is 1 / 6 of the cycle.

[0039] In some embodiments, the first phase modulation region 1451 is 0-phase modulation, the second phase modulation region 1452 is π-phase modulation, and the phase plate 141 is composed of square transmission modulation regions of 0-phase modulation and π-phase modulation arranged periodically in a chessboard pattern. It can diffract light of equal intensity into four beams, each located at a vertex of the square, thus facilitating its use in transverse shearing interference.

[0040] In some embodiments, the masking frame 146 is opaque; specifically, the masking frame 146 is a black frame. Adding a masking frame 146 to the grid edges of the phase modulation region 145, with the width of the masking frame 146 being half the side length of the phase modulation region 145, although this results in some loss of light intensity, can suppress secondary diffraction spots outside the four main diffraction spots, thereby reducing multi-pixel coupling of shearing interference and simplifying the analytical algorithm. When coherent light illuminates the phase plate 141, four-wave shearing interference can be generated.

[0041] In some embodiments, the phase plate 141 forms a thickness difference between the first phase modulation region 1451 and the second phase modulation region 1452 through a photolithography process, so that the phase difference generated by light passing through the first phase modulation region 1451 and the second phase modulation region 1452 is π.

[0042] In some embodiments, such as Figure 2 As shown, the light output from the light source 110 passes through the aperture array plate 120 and the lens under test 130 to form an aperture array image 1202. The phase plate 141 is closer to the lens under test 130 than the aperture array image 1202.

[0043] In some embodiments, the phase plate 141 is located between the lens under test 130 and the aperture array image 1202, and there is a gap distance z between the phase plate 141 and the aperture array image 1202, the size of the gap distance z being on the order of hundreds of micrometers. The setting of the gap distance z ensures that the light energy of a single light-transmitting aperture 1201 illuminates most of the phase modulation regions 145, rather than being focused on a single point to form modulation.

[0044] In some embodiments, the size of the interval distance z is 50μm-1000μm. Specifically, the size of the interval distance z is 50μm, 74.5μm, 100μm, 150μm, 200μm, 225μm, 300μm, 500μm, 1000μm, and any value between the above values.

[0045] In some embodiments, the wavefront aberration detection device 10 further includes a workpiece stage. When the workpiece stage controls the phase plate 141 to adjust up and down, as the distance between the phase plate 141 and the aperture array image 1202 approaches, the light spot on the interferogram will appear larger and larger until a single point fills the entire interferogram field of view, which is the case of near coincidence. After the phase plate 141 is deviated from the coincidence position, a light spot array will appear in the interferogram field of view. The denser the number of points in the array, the denser the spatial frequency sampling of the wavefront measurement, but the fewer the pixels for each phase information, and the worse the accuracy. A spacing distance z of hundreds of micrometers is a suitable balance point, satisfying both sufficient light spot array and ensuring accuracy.

[0046] In some embodiments, the wavefront aberration detection device 10 includes a light source 110, an aperture array plate 120, a lens under test 130, and a wavefront detection module 140 arranged sequentially along the light propagation path. The wavefront detection module 140 includes a phase plate 141, an aspherical lens 142, and a photosensitive unit 143 arranged sequentially along the light propagation path.

[0047] In some embodiments, the aperture array image 1202 is located at the object-side focal plane of the aspherical lens 142, and the photosensitive unit 143 is located at the image-side focal plane of the aspherical lens 142. That is, the distance from the aperture array image 1202 to the object-side principal plane of the aspherical lens 142 is the object-side focal length f. a The distance from the photosensitive unit 143 to the image-side principal plane of the aspherical lens 142 is the image-side focal length f. b .

[0048] In some embodiments, the object-side focal length f of the aspherical lens 142 a Image focal length f b They are equal in size.

[0049] In some embodiments, the lens under test 130 may be formed by combining multiple lenses. In some embodiments, the lens under test 130 is an objective lens.

[0050] In some embodiments, the aspherical lens 142 is an aspherical high numerical aperture lens, which converts the interference signal to the pupil plane through Fourier transform, so as to project the four-wave shearing interference pattern generated by the phase plate 141 onto the photosensitive unit 143.

[0051] In some embodiments, the wavefront detection module 140 further includes a light shield, with a phase plate 141 located in the middle of the light shield. When light from a single light-transmitting hole 1201 passes through the phase plate 141, the light shield can block the light from other light-transmitting holes 1201.

[0052] In some embodiments, the photosensitive unit 143 may be a CMOS array screen, a CCD array, or an InGaAs detector array, etc.

[0053] In scenarios with incoherent light input, to measure the wavefront modulation distribution of the lens under test 130, the optical path of the wavefront aberration detection device 10 needs to be designed. Illumination light with a large diffusion angle is emitted from the incoherent light source 110, passes through the aperture array plate 120, enters the lens under test 130, and is modulated and imaged onto the aperture array image 1202 by the lens under test 130. The wavefront detection module 140 has a limited light-receiving range, and its pupil only receives the single aperture image in the aperture array image 1202. Then, the light is modulated and imaged onto the photosensitive unit 143 by the phase plate 141 and the large numerical aperture aspherical lens 142 in the wavefront detection module 140 to obtain an interference image. The wavefront detection module 140 is supported by the workpiece stage and can perform long-stroke, high-precision movement. To ensure signal quality, the spacing of the light-transmitting apertures 1201 is designed to match the light-receiving range of the wavefront detection module 140. When the image of one light-transmitting aperture 1201 moves out of the range, the images of other light-transmitting apertures 1201 can enter the light-receiving range.

[0054] The wavefront aberration detection device 10 provided in this application, by rationally arranging a hole array plate 120 on the mask surface and arranging an aspherical lens 142 behind the phase plate 141, combined with a high-precision displacement workpiece stage, allows the incoherent light output from the light source 110 to be received by the wavefront detection module 140 through the light transmission hole 1201 and generate a four-wave shearing interferogram, thereby realizing full-field wavefront aberration detection under incoherent illumination conditions. The wavefront aberration detection device 10 has the characteristics of high integration and high precision. It can be integrated into processing equipment to achieve in-situ high-precision detection, which can significantly improve processing efficiency and avoid workpiece scrap caused by over-processing. It can also be integrated into lithography equipment to achieve online wavefront aberration detection, providing sufficient feedback to maintain high-precision imaging.

[0055] This application also provides a wavelet aberration detection method, such as... Figure 4 As shown, wavelet aberration detection methods include: Step S100: The light output from the light source 110 passes through the aperture array plate 120 and the lens under test 130 and then illuminates the wavefront detection module 140, generating multiple interference signals.

[0056] Step S200: Based on multiple interference information, analyze and obtain the wavelet aberration information of the lens 130 under test.

[0057] The aperture array plate 120 is provided with multiple light-transmitting holes 1201, and multiple interference information corresponds one-to-one with multiple light-transmitting holes 1201.

[0058] In some embodiments, the light output by the light source 110 is incoherent light. The incoherent light passes through the light-transmitting aperture 1201 to form approximately coherent light, and the light transmitted through each light-transmitting aperture 1201 can generate corresponding interference information.

[0059] In some other embodiments, the light output by the light source 110 is coherent light.

[0060] In some embodiments, such as Figure 5 As shown, step S100 includes: Step S110: The light output from the light source 110 passes through the aperture array plate 120 and the lens under test 130 to form an aperture array image 1202.

[0061] A single light-transmitting hole 1201 can form a corresponding aperture image, and multiple light-transmitting holes 1201 can form an aperture array image 1202 composed of multiple aperture images.

[0062] Step S120: Move the wavefront detection module 140 along the plane where the aperture array image 1202 is located, so as to receive the images formed by different light-transmitting apertures 1201 in sequence and generate corresponding interference information.

[0063] In some embodiments, the wavefront detection module 140 detects interference information corresponding to only one light-transmitting aperture 1201 at a time to ensure signal quality. By moving the wavefront detection module 140, the detection of interference information corresponding to different light-transmitting apertures 1201 can be switched.

[0064] In some embodiments, the wavefront detection module 140 includes a phase plate 141, which is used to receive light transmitted through the lens 130 under test and generate four-wave shearing interference. The phase plate 141 is closer to the lens 130 under test than the aperture array image 1202.

[0065] In some embodiments, such as Figure 6 As shown, step S200 includes: Step S210: Analyze the wavefront aberration of the field of view corresponding to each light-transmitting hole 1201 based on the interference information corresponding to each light-transmitting hole 1201.

[0066] Step S220: Obtain the wavefront aberration information of the lens 130 under test based on the wavefront aberration analysis of the multiple fields of view corresponding to the multiple light-transmitting holes 1201.

[0067] The wavefront detection module 140 can move to detect wavefront aberrations in more than 130 fields of view of the lens under test. By combining wavefront aberration analysis of multiple fields of view, wavefront aberration information of the entire field of view can be obtained.

[0068] In some embodiments, such as Figure 7 As shown, step S210 includes: Step S211: Move the wavefront detection module 140 to obtain the wavefront aberration of the field of view corresponding to each light-transmitting hole 1201 based on the moving trajectory analysis of the characteristic spots of the interference information.

[0069] The interference information includes a four-wave shearing interferogram, which contains multiple characteristic spots. The wavefront detection module 140 can move within a small range relative to the aperture array plate 120, so that the four-wave shearing interferogram generated by a single light-transmitting aperture 1201 changes, without causing the images formed by other light-transmitting apertures 1201 to enter the light-receiving range of the wavefront detection module 140.

[0070] Depending on the required wavefront spatial frequency to be measured, completely different algorithm designs can be employed. For simple primary aberration measurements, the spacing between the phase plate 141 and the aperture array image 1202 can be reduced to make the number of interference feature spots in the entire interferogram sparser, facilitating rapid measurement of primary aberrations, such as... Figure 9 As shown. The first-order terms of primary aberrations are tilt and defocus: where tilt is the overall translation, one set being lateral and the other longitudinal, which can be determined by the total center of the interferogram; defocus is the overall scaling, which can be determined by the average spacing of the interferogram grid, as shown. Figure 10 As shown. The second-order terms in primary aberrations are astigmatism, coma, and spherical aberration: Astigmatism corresponds to compression, specifically the difference in grid spacing in two orthogonal directions, one set being the horizontal and vertical directions, and the other set being the two diagonal directions. These can be determined by variations in grid spacing and the angle between them, as shown below. Figure 11 As shown; coma corresponds to a trapezoidal effect, specifically, the grid spacing changes linearly with image coordinates. One set changes with the horizontal coordinate, and the other with the vertical coordinate. Both can be determined by linear regression of the grid spacing, such as... Figure 12 As shown; the spherical aberration corresponds to the quadratic change in grid spacing with radius, which can be determined by a quadratic fit of the grid spacing, as follows. Figure 13 As shown.

[0071] If higher wavefront distribution sampling is required, corresponding to a higher Zernike order in the aberrations, the spacing between the phase plate 141 and the aperture array image 1202 needs to be increased to make the initial interference feature spots denser. Measuring the change in grid spacing distribution can then yield higher-order wavefront aberrations. However, since the number of pixels corresponding to each feature spot decreases, the accuracy of sub-pixel fitting also decreases. Therefore, it is equivalent to sacrificing phase measurement accuracy in exchange for sampling of the phase spatial distribution.

[0072] This application designs a movable wavefront detection module 140 to increase phase spatial distribution sampling without sacrificing phase measurement accuracy. The wavefront detection module 140 obtains the phase distribution by observing the trajectory drawn by the characteristic spot position in different directions of movement.

[0073] In some embodiments, the wavefront aberration detection device 10 includes a workpiece stage for moving the wavefront detection module 140. Since the workpiece stage needs to be moved for time-series measurements, the detection method using a movable wavefront detection module 140 sacrifices the measurement frame rate to the second level, making it suitable for systems with slow changes, which is perfectly suited for objective lens measurements.

[0074] In some embodiments, such as Figure 8 As shown, step S211 includes: Step S2111: Move the wavefront detection module 140 in the lateral direction to obtain the movement trajectory of the feature spot as the contour line of the longitudinal gradient of the wavefront phase distribution.

[0075] Step S2112: Move the wavefront detection module 140 in the longitudinal direction to obtain the movement trajectory of the feature spot as the contour line of the transverse gradient of the wavefront phase distribution.

[0076] The horizontal and vertical directions are perpendicular, and the planes containing the horizontal and vertical directions are parallel to the plane containing the hole array plate 120.

[0077] In some embodiments, the lateral direction and the longitudinal direction are the extension directions of the two adjacent sides of the phase modulation region 145, respectively.

[0078] In some embodiments, step S211 further includes: Step S2113: Based on the contour lines, use an interpolation algorithm to obtain the gradient distribution in the transverse and longitudinal directions of the wavefront phase distribution; Step S2114: Based on the gradient distribution, obtain the wavefront phase distribution using numerical integration.

[0079] In some embodiments, step S211 further includes: Step S2115: Based on the wavefront phase distribution, the higher-order Zernike term is obtained by projection integration.

[0080] In some embodiments, interpolation algorithms include Lagrange interpolation, Newton interpolation, linear interpolation, bilinear interpolation, Kriging interpolation, or constrained triangular mesh interpolation. Numerical integration methods include the rectangular method, trapezoidal method, Simpson's method, or Gaussian integration. Projective integration methods include direct orthogonal projection integration.

[0081] In some embodiments, such as Figure 14As shown, during the detection process of the wavefront detection module 140, the workpiece stage is first moved laterally, and the movement trajectory of the interference feature spot indicates the contour lines of the longitudinal gradient of the wavefront phase distribution; then the workpiece stage is moved longitudinally, and the movement trajectory of the interference feature spot indicates the contour lines of the transverse gradient of the wavefront phase distribution; the gradient distribution in two directions can be obtained from the contour lines through various suitable interpolation algorithms, and then the wavefront phase distribution can be obtained from the gradient distribution in two directions through numerical integration; the wavefront phase distribution can be used to analyze the wavefront aberration of the field of view corresponding to a single aperture 1201, and then the wavefront aberration information of the lens 130 under test can be obtained by analyzing the wavefront aberration of multiple fields of view corresponding to multiple apertures 1201.

[0082] In some embodiments, this application also provides a wavefront aberration detection device 10, which uses the wavefront aberration detection method described above to measure the wavefront aberration information of the lens 130 under test.

[0083] In some embodiments, the wavefront detection device 10 includes a light source 110, an aperture array plate 120, a lens under test 130, and a wavefront detection module 140 arranged sequentially along the light propagation path.

[0084] The wavefront aberration detection method provided in this application designs a workpiece stage motion mode and a phase gradient contour processing algorithm to achieve more refined wavefront distribution acquisition and overcome the limitation of the sampling interval on the spacing between the phase plate 141 and the aperture array image 1202.

[0085] This application embodiment also provides a method for manufacturing a phase plate 141, such as... Figure 15 and Figure 16 As shown, the manufacturing method includes: Step S300: Provide substrate 200.

[0086] Step S400: Alternating grooves 201 and protrusions 210 are formed on substrate 200.

[0087] Step S500: A shielding frame 146 is provided on the substrate 200, and the shielding frame 146 surrounds and forms a phase modulation region 145.

[0088] In some embodiments, the edge 250 of the groove 201 is covered by a shielding frame 146. The edge 250 of the groove 201 is an uneven transition portion between the groove 201 and the protrusion 210. Due to the influence of process deviations during manufacturing, the position of the edge 250 can easily cause differences in phase design, affecting the optical effect. Covering the edge 250 with the shielding frame 146 can prevent light from passing through the vicinity of the edge 250, ensuring the optical effect and improving the manufacturing yield of the phase plate 141. At the same time, adding the shielding frame 146 at the edge of the phase modulation region 145 can suppress secondary diffraction spots other than the main diffraction spot, simplifying the analytical algorithm.

[0089] In some embodiments, the fabrication method can be used to fabricate diffractive optical elements, and can also be used to fabricate checkerboard-shaped phase plates 141, or other periodic phase diffractive elements.

[0090] The fabrication of diffractive optical elements requires semiconductor processes. Utilizing the thickness difference of a transparent medium to generate a phase difference with almost constant light intensity is currently the simplest and most economical approach, offering both cost advantages and ease of control. In some embodiments, the substrate 200 in this application is a transparent medium. By designing different thicknesses for the grooves 201 and protrusions 210 on the substrate 200, a phase difference can be generated. The shielding frame 146 is an opaque medium; for example, it can be a black frame. Utilizing the opaque medium achieves shielding, there are no strict requirements on the thickness of the shielding frame 146, as long as it is thick enough to achieve the shielding function, simplifying the fabrication process. Since the phase plate 141 has at least two phases in its transparent portion and also contains opaque portions, at least two photolithography processes are required: one to create the thickness difference of the transparent medium, and another to complete the additive manufacturing of the opaque medium. Precise overlay support is often required between two photolithography steps. This application, through reasonable design of process steps, places the part most prone to overlay differences in the black frame structure of the shielding frame 146. Since the black frame is opaque, inaccuracies inside will not affect the subsequent light field, thus allowing for a larger tolerance. The overlay accuracy requirement only needs to be within half the width of the shielding frame 146.

[0091] In some embodiments, the phase modulation region 145 includes a first phase modulation region 1451 and a second phase modulation region 1452. The phase difference generated by light passing through the first phase modulation region 1451 and the second phase modulation region 1452 is π. The first phase modulation region 1451 is disposed in the groove 201, and the second phase modulation region 1452 is disposed in the protrusion 210. The blocking frame 146 is disposed around the groove 201 to form the first phase modulation region 1451, and the blocking frame 146 is disposed around the protrusion 210 to form the second phase modulation region 1452.

[0092] In some embodiments, the phase plate 141 is used to generate four-wave shearing interference, and the width of the shielding frame 146 is half the side length of the phase modulation region 145, so as to better suppress secondary diffraction spots in addition to the four main diffraction spots, thereby reducing multi-pixel coupling of the shearing interference.

[0093] In some embodiments, the substrate 200 in step S300 is a double-sided polished transparent wafer, prepared by cleaning and surface oxygen plasma treatment.

[0094] In some embodiments, such as Figure 17 As shown, step S400 includes: Step S410: Set the first adhesive block 220 on the substrate 200.

[0095] Step S420: Subtractive fabrication is performed on substrate 200 to form groove 201 and protrusion 210.

[0096] Step S430: Wash away the first adhesive block 220.

[0097] In some embodiments, the first adhesive block 220 can be photoresist. By subtractive manufacturing methods such as etching, a groove 201 can be formed on the substrate 200 where the first adhesive block 220 is not covered, and a protrusion 210 can be formed on the covered area of ​​the first adhesive block 220.

[0098] In some embodiments, step S420 may also be additive manufacturing of the substrate 200, adding a new transparent medium to the substrate 200 to form a protrusion 210, and forming a groove 201 between adjacent protrusions 210.

[0099] In some embodiments, such as Figure 18 As shown, step S410 includes: Step S411: Form an adhesive layer on the substrate 200; Step S412: Expose the adhesive layer to form the first adhesive block 220.

[0100] In some embodiments, such as Figure 19 As shown, step S500 includes: Step S510: A shielding layer 230 is formed on the substrate 200 by additive manufacturing.

[0101] Step S520: Set the second adhesive block 240 on the shielding layer 230.

[0102] Step S530: The shielding layer 230 is manufactured by subtractive processing to form the shielding frame 146.

[0103] Step S540: Wash away the second adhesive block 240.

[0104] In some embodiments, the shielding layer 230 in step S510 covers one side of the substrate 200, including a covering groove 201 and a protrusion 210. The second adhesive block 240 can be photoresist, and the uncovered areas of the second adhesive block 240 on the shielding layer 230 can be eliminated by subtractive manufacturing such as etching, while the covered areas of the second adhesive block 240 form a shielding frame 146.

[0105] In some embodiments, the second adhesive block 240 can be formed by depositing an adhesive layer on the masking layer 230 and then exposing the adhesive layer.

[0106] In some embodiments, step S530 includes: Step S531: Subtractive fabrication is performed on the shielding layer 230 and the substrate 200 to ensure that the phase modulation region 145 is not shielded.

[0107] Since the shielding layer 230 covers the phase modulation region 145 in step S510, to ensure that the shielding layer 230 at the corresponding position of the phase modulation region 145 can be completely eliminated, after the subtractive manufacturing process eliminates the shielding layer 230, a portion of the substrate 200 can be further removed so that the phase modulation region 145 is not shielded. In some embodiments, the substrate 200 may have a reserved thickness so that it can be eliminated along with the shielding layer 230 during the subtractive manufacturing process.

[0108] In some embodiments, additive manufacturing methods, represented by growth, can be processes such as sputtering deposition, vapor deposition, and crystallization, while subtractive manufacturing methods, represented by etching, can be processes such as chemical etching, electro-etching, gas etching, plasma directional etching, and particle bombardment.

[0109] In some embodiments, the fabrication method includes the following steps: The first step is to prepare a double-sided polished transparent substrate wafer, including cleaning and surface oxygen plasma treatment; the second step is to expose a pattern with corresponding thickness differences (here, a checkerboard pattern is used as an example, i.e., a structure of alternating transparent and opaque squares resembling chess pieces) onto the photoresist after photoresist coating and pre-baking, followed by development and post-baking to ensure that the photoresist-covered area matches the pattern of the area requiring thickness differences in the design; the third step is to perform subtractive or additive manufacturing of a new transparent medium on the transparent substrate, so that the thickness difference between the photoresist-masked and unmasked portions precisely meets the design phase difference (…). The phase difference is π), and then the photoresist is washed away; the fourth step is to perform additive manufacturing of opaque material to make the whole thing opaque; the fifth step is to perform photolithographic exposure of the masking frame 146 pattern and overlay it with the pattern made in the second step, so that the edge of the photoresist-protected area is covered by the masking frame 146 made in the sixth step to cover the uneven transition part of the pattern in the second step; the sixth step is to perform selective subtractive manufacturing of opaque material, only removing opaque material, while keeping the thickness difference of transparent material at the designed phase difference (or making a certain amount of extra allowance in the second step of the process, which exactly cancels out the extra part etched in this step), thus completing the fabrication of the diffractive optical element.

[0110] By designing the steps of the manufacturing method, even if there is a large difference in the overprinting between the second and fifth steps, as long as the transition area does not deviate from the occlusion frame 146, the optical effect will not change, thus achieving a large overprinting tolerance.

[0111] This application also provides a phase plate 141, which is manufactured using the manufacturing method described in the above embodiments.

[0112] In some embodiments, the phase plate 141 is used to generate four-wave shearing interference, and the phase modulation region 145 includes a first phase modulation region 1451 and a second phase modulation region 1452, which are arranged in a checkerboard pattern and alternate periodically.

[0113] The method for fabricating the phase plate 141 and the phase plate 141 provided in this application optimize the structural design and fabrication process of the phase plate 141 in the self-interference optical path. By designing the manufacturing process of the process pattern structure, the fabrication yield of the phase plate 141 can be increased to reduce the influence of higher-order diffraction peaks, thereby improving the spatial sampling frequency of the wavefront at the same cost.

[0114] The above description is only a part of the embodiments of this application and does not limit the scope of protection of this application. Any equivalent device or equivalent process transformation made based on the content of this application specification and drawings, or direct or indirect application in other related technical fields, are similarly included in the patent protection scope of this application.

Claims

1. A wavelet aberration detection device, characterized in that, include: A light source used to output incoherent light; A hole array plate is disposed between the light source and the lens under test, and the hole array plate is provided with multiple light-transmitting holes; The wavefront detection module is used to detect the wavefront aberration information of the lens under test; The light emitted by the light source passes through the light-transmitting hole and the lens under test, and can be received by the wavefront detection module to generate interference information.

2. The wavelet aberration detection device according to claim 1, characterized in that, The wavefront detection module can move relative to the aperture array plate to receive light transmitted through different apertures and generate corresponding interference information. The plane on which the wavefront detection module moves is parallel to the plane on which the aperture array plate is located.

3. The wavelet aberration detection device according to claim 2, characterized in that, The spacing between adjacent light-transmitting holes is adapted to the light-receiving range of the wavefront detection module. When the wavefront detection module receives the image formed by one of the light-transmitting holes, the images formed by the other light-transmitting holes are located outside the light-receiving range of the wavefront detection module.

4. The wavelet aberration detection device according to claim 2, characterized in that, The wavefront detection module can move relative to the aperture array plate to detect the movement trajectory of the feature spot in the interference information corresponding to a single aperture, and obtain the wavefront aberration of the field of view corresponding to the aperture based on the movement trajectory.

5. The wavelet aberration detection device according to claim 1, characterized in that, The wavefront detection module includes a phase plate, which is used to receive the light transmitted through the lens under test and generate four-wave shearing interference.

6. The wavelet aberration detection device according to claim 5, characterized in that, The light emitted by the light source passes through the aperture array plate and the lens under test to form an aperture array image, and the phase plate is closer to the lens under test than the aperture array image.

7. The wavelet aberration detection device according to claim 6, characterized in that, The spacing between the aperture array plate and the aperture array image is 50μm-1000μm.

8. The wavelet aberration detection device according to claim 5, characterized in that, The wavefront detection module includes a phase plate, an aspherical lens, and a photosensitive unit arranged sequentially along the light propagation path.

9. The wavelet aberration detection device according to claim 5, characterized in that, The phase plate includes multiple phase modulation regions, including a first phase modulation region and a second phase modulation region. The phase difference generated by the light transmitted through the lens under test through the first phase modulation region and the second phase modulation region is π. The first phase modulation region and the second phase modulation region are arranged in a periodic alternation.

10. The wavelet aberration detection device according to claim 9, characterized in that, The edge of the phase modulation region is provided with a blocking frame, the width of which is half the side length of the phase modulation region.

Images