Phase measurement deflectometry wavefront measurement device and method based on vortex focusing lens

Abstract

A phase measurement deflectometry wavefront measurement device and method based on a vortex focusing lens comprises a display screen, a vortex focusing lens, a rotating mirror frame, a filter pinhole, a focusing lens, an object to be measured, a first three-dimensional translation stage, an image acquisition module, a second three-dimensional translation stage and a computer. The present invention obtains incident vortex stripe light beams with different phase shifts by rotating the vortex focusing lens, utilizes the object-image relationship between the object to be measured and the target surface of a detection system, and then utilizes the image acquisition module to record the intensity information of the incident vortex stripe light beam before and after passing through the wave to be measured, thereby combining a multi-step phase shift algorithm, a regional wavefront reconstruction algorithm, etc. to realize accurate reconstruction of the wavefront to be measured; the present invention has a compact structure, low cost, simple operation, and high detection accuracy, can avoid the use of expensive laser light sources, can expand the application scope of wavefront measurement devices, and can provide a new technical solution for the civilian and commercialization of phase measurement deflectometry.

Description

Technical Field

[0001] The invention belongs to phase measurement deflectometry, and in particular to a phase measurement deflectometry wavefront measurement device and method based on a vortex focusing lens. Background Art

[0002] Phase measurement deflectometry uses a screen to project fringes onto the surface of the object to be measured, and then calculates the morphological information of the surface of the object to be measured based on the captured fringes information; this technology has attracted much attention due to its potential application value in astronomical observation, modern industrial inspection, microscopic measurement and other fields. In astronomical observation, the University of Arizona proposed an optical inspection model based on phase measurement deflectometry, which can be used to measure the secondary mirror of the Large Survey Telescope with a diameter of 5m, the primary mirror of the Large Magellan Telescope with a diameter of 8.4m, and the surface shape of the precision X-ray reflector and the surface shape of the Inouye Solar Telescope, and its detection accuracy is comparable to that of an interferometer; in modern industrial inspection, the inspection system based on phase measurement deflectometry can be used for the paint spraying condition of automobile bodies, can be used for ultra-precision turning to obtain high-precision free-form surfaces, can be used for defect detection of artificial lenses, etc.; in microscopic measurement, Hausler et al. measured the surface shape of nanometer-sized mirrors based on the principle of phase measurement deflectometry, and further applied this method to microscopic measurement of transparent objects. The application of phase measurement deflectometry in various fields is increasing, and the research on detection devices and detection methods based on phase measurement deflectometry is becoming increasingly important.

[0003] Knauer et al. proposed phase measurement deflectometry, which has many advantages such as non-contact, low cost, high detection accuracy, easy operation, no need for complex devices, wide dynamic range, strong anti-interference ability, fast detection speed, and full field of view. Wang Wei et al. used a computer to generate phase-shifted sinusoidal stripe structured light as a light source in CN111537203A. The structured light passed through the lens to be tested to form a deformed stripe structured light, and then phase measurement deflectometry was used to obtain the wavefront distribution of the optical lens. This method has a simple structure, but the intensity information measured by the detection system in this type of optical device is often the intensity information of the light beam emitted from the object to be tested after a certain distance. The phase error introduced in the diffraction transmission process will reduce the imaging and detection accuracy of the device. Summary of the invention

[0004] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a phase measurement deflectometry wavefront measurement device and method based on a vortex focusing lens, so as to realize high-precision reconstruction of the wavefront to be measured, and combine the Kepler telescope system composed of double focusing lenses, and utilize the object-image relationship between the object to be measured and the target surface of the detection system to improve the detection accuracy of the wavefront measurement device; by rotating the vortex focusing lens phase shifter to obtain different incident vortex stripe light beams with different phase shifts, and then using the image acquisition module to record the intensity information map of the incident vortex stripe light beam before and after passing through the wave to be measured, so as to realize accurate reconstruction of the transmission wavefront to be measured by combining the multi-step phase shift algorithm, the regional wavefront reconstruction algorithm, etc. The detection device is simple to operate, simple in structure, low in cost, high in detection accuracy, high in robustness, can realize the wavefront reproduction of the wavefront to be measured, can avoid the use of expensive laser light sources, and provides a new technical solution for the civilian and commercialization of phase measurement deflectometry.

[0005] Technical solution of the present invention

[0006] A phase measurement deflectometry wavefront measurement device based on a vortex focusing lens is characterized in that it comprises a display screen, a vortex focusing lens, a rotating mirror frame for placing the vortex focusing lens, a filter aperture, a focusing lens, a first three-dimensional translation stage for placing an object to be measured, an image acquisition module, a second three-dimensional translation stage for placing the image acquisition module, and a computer, wherein the output ends of the display screen and the image acquisition module are respectively connected to the input end of the computer;

[0007] The vortex focusing lens, the filter pinhole and the focusing lens constitute a 4f system, and the filter pinhole is located on the spectrum plane of the 4f system;

[0008] The display screen is used to display the vortex stripe light beam generated by the computer. The vortex stripe light beam is used as a light source. It passes through the vortex focusing lens and the filter pinhole in sequence and reaches the focusing lens. The light beam collimated by the focusing lens is used as an incident vortex stripe light beam. By rotating the rotating mirror frame, the vortex focusing lens is driven to obtain incident vortex stripe light beams with different phase shifts.

[0009] After the incident vortex stripe light beam is refracted by the object to be measured, it is collected by the image acquisition module. By moving the first three-dimensional translation stage and the second three-dimensional translation stage, a refraction intensity map of the object to be measured appears on the image acquisition module and is transmitted to the computer.

[0010] The vortex focusing lens is a circular vortex focusing lens or an elliptical vortex focusing lens with a desired topological charge, or other vortex light beams that can generate different topological charges and eccentricities.

[0011] The object to be measured is a single lens, a combined lens or other phase-type object.

[0012] The computer controls the movement of the first three-dimensional translation stage and the second three-dimensional translation stage respectively.

[0013] A phase measurement deflectometry wavefront measurement method is performed using any of the measurement devices, wherein the method comprises the following steps:

[0014] 1) Turn on the display screen, and the vortex stripe light beam emitted by the display screen is incident on the vortex focusing lens;

[0015] Rotate the mirror frame, the rotation angles are Wherein, the positive integer N is the number of rotations of the rotating mirror frame, and N≥3, n=1,2,3...N, L is the topological charge of the vortex focusing lens, and the incident vortex stripe light beams with different phase shifts are obtained after being emitted from the focusing lens;

[0016] The incident vortex stripe light beam is refracted by the object to be measured and then emitted at a certain deflection angle to obtain a deformed vortex stripe light beam;

[0017] The first three-dimensional translation stage and the second three-dimensional translation stage are moved to drive the object to be measured and the image acquisition module, so that the refraction intensity image I of the object to be measured appears on the image acquisition module. n (x,y,θ n ), where (x, y) is the spatial coordinate distribution of the recording surface;

[0018] The image acquisition module respectively records the refraction intensity image I of the incident vortex stripe light beam with different phase shifts passing through the object to be measured. n (x,y,θ n ), and transmitting the collected intensity data to the computer;

[0019] 2) Based on the recorded multiple refraction intensity images I n (x,y,θ n ) calculate the phase distribution of the object to be measured on the recording surface The formula is as follows:

[0020]

[0021] 3) Obtain the true phase distribution of the object to be measured by unwrapping operation Then, the optical inverse tracing method is used to obtain the wavefront slope distribution of the object to be measured, and the formula is as follows:

[0022]

[0023] Wherein, p is the fringe period, d is the distance from the object to be measured to the image acquisition module, is the phase change caused by the object to be measured at a pixel point, θ x and θ y are the light deflection angle components of the incident vortex stripe beam in the x direction and the y direction respectively;

[0024] The wavefront slope W of the wavefront to be measured and the light deflection angle component θ x and θ y The relationship is as follows:

[0025]

[0026] In combination with the above relationship, the wavefront distribution of the object to be measured can be obtained by numerically integrating the wavefront slope using a regional wavefront reconstruction algorithm.

[0027] Compared with the prior art, the technical effects of the present invention are:

[0028] 1) The present invention combines the Kepler telescope system and utilizes the object-image relationship between the object to be measured and the target surface of the detection system to improve the imaging accuracy of the imaging device.

[0029] 2) The present invention obtains an incident vortex stripe light beam with different phase shifts by rotating the vortex focusing lens, and then uses an image acquisition module to record the intensity information of the incident vortex stripe light beam before and after passing through the wave to be measured, thereby combining a multi-step phase shift algorithm, a regional wavefront reconstruction algorithm, etc. to achieve accurate reconstruction of the wavefront to be measured.

[0030] 3) The present invention can avoid the use of expensive laser light sources, expand the application scope of wavefront measurement devices, and provide a new technical solution for the civilian and commercialization of phase measurement deflectometry. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of the phase measurement deflectometry wavefront measurement device based on the vortex focusing lens of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with embodiments and drawings, but the protection scope of the present invention shall not be limited thereto.

[0033] Please refer to Figure 1 , Figure 1The present invention is a schematic structural diagram of a phase measurement deflectometry wavefront measurement device based on a vortex focusing lens, comprising a display screen 1, a vortex focusing lens 2, a rotating mirror frame 3 for placing the vortex focusing lens 2, a filter aperture 4, a focusing lens 5, a first three-dimensional translation stage 7 for placing an object to be measured 6, an image acquisition module 8, a second three-dimensional translation stage 9 for placing the image acquisition module 8, and a computer 10, wherein the output ends of the display screen 1 and the image acquisition module 8 are respectively connected to the input end of the computer 10;

[0034] The vortex focusing lens 2, the filter aperture 4 and the focusing lens 5 constitute a 4f system, and the filter aperture 4 is located on the spectrum plane of the 4f system;

[0035] The display screen 1 is used to display the vortex stripe light beam generated by the computer 10. The vortex stripe light beam is used as a light source, and reaches the focusing lens 5 after passing through the vortex focusing lens 2 and the filter aperture 4 in sequence. The light beam collimated by the focusing lens 5 is used as an incident vortex stripe light beam. By rotating the rotating mirror frame 3, the vortex focusing lens 2 is driven, thereby obtaining incident vortex stripe light beams with different phase shifts.

[0036] After the incident vortex fringe light beam is refracted by the object to be measured 6, it is collected by the image acquisition module 8. By moving the first three-dimensional translation stage 7 and the second three-dimensional translation stage 9, a refraction intensity map of the object to be measured 6 appears on the image acquisition module 8 and is transmitted to the computer 10.

[0037] The vortex focusing lens 2 is a circular vortex focusing lens or an elliptical vortex focusing lens with a desired topological charge, or other vortex beams that can generate different topological charges and eccentricities;

[0038] The object to be measured 6 is a single lens, a combined lens or other phase type object;

[0039] The computer 10 controls the movement of the first three-dimensional translation stage 7 and the second three-dimensional translation stage 9 respectively;

[0040] The measuring device is used to perform a phase measurement deflectometry wavefront measurement method, which is characterized in that the method comprises the following steps:

[0041] 1) Turn on the display screen 1, and the vortex stripe light beam emitted by the display screen 1 is incident on the vortex focusing lens 2;

[0042] Rotate the rotating mirror frame 3, the rotation angles are θ1 = 0°, and Wherein, L is the topological charge of the vortex focusing lens 2, so that the phase shifts of the emission from the focusing lens 5 are 0, π, The incident vortex stripe beam;

[0043] The incident vortex stripe light beam is refracted by the object to be measured 6 and then emitted at a certain deflection angle to obtain a deformed vortex stripe light beam;

[0044] The first three-dimensional translation stage 7 and the second three-dimensional translation stage 9 are moved to drive the object to be measured 6 and the image acquisition module 8, so that the refraction intensity image I of the object to be measured 6 appears on the image acquisition module 8. n (x,y,θ n ), where (x, y) is the spatial coordinate distribution of the recording surface;

[0045] The image acquisition module 8 respectively records the refraction intensity images I of the incident vortex stripe light beams with different phase shifts passing through the object to be measured 6. n (x,y,θ n ), and transmit the collected intensity data to the computer 10;

[0046] 2) Based on the recorded multiple refraction intensity images I n (x,y,θ n ) Calculate the phase distribution of the object to be measured 6 on the recording surface according to the multi-step phase shift formula The specific formula is as follows:

[0047] Three-step phase shift formula: Four-step phase shift formula:

[0048] 3) Obtain the real phase distribution of the object to be measured 6 by unwrapping operation Then, the optical inverse tracing method is used to obtain the wavefront slope distribution of the object to be measured 6, and the formula is as follows:

[0049]

[0050] Wherein, p is the fringe period, d is the distance from the object to be measured 6 to the image acquisition module 8, is the phase change caused by the object 6 at one pixel, θ x and θ y are the light deflection angle components of the incident vortex stripe beam in the x direction and the y direction respectively.

[0051] The wavefront slope W of the wavefront to be measured and the light deflection angle component θ x and θ y There are the following relationships:

[0052]

[0053] In combination with the above relationship, the wavefront distribution of the object to be measured 6 can be obtained by numerically integrating the wavefront slope using a regional wavefront reconstruction algorithm.

[0054] Experiments show that the present invention has a simple and compact structure, low cost, simple operation, high detection accuracy and high robustness. It can obtain an incident vortex stripe light beam with different phase shifts by rotating the vortex focusing lens, and can be combined with a multi-step phase shift algorithm, a regional wavefront reconstruction algorithm, etc. to achieve accurate reconstruction of the wavefront to be measured, avoid the use of expensive laser light sources, expand the application range of the wavefront measurement device, and provide a new technical solution for the civilian and commercialization of phase measurement deflectometry.

[0055] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific implementation case of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement or improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A phase measurement deflectometry wavefront measurement device based on a vortex focusing lens, characterized in that: The device comprises a display screen (1), a vortex focusing lens (2), a rotating mirror frame (3) for placing the vortex focusing lens (2), a filtering aperture (4), a focusing lens (5), a first three-dimensional translation stage (7) for placing an object to be measured (6), an image acquisition module (8), a second three-dimensional translation stage (9) for placing the image acquisition module (8), and a computer (10), wherein the output ends of the display screen (1) and the image acquisition module (8) are respectively connected to the input end of the computer (10); The vortex focusing lens (2), the filtering aperture (4) and the focusing lens (5) constitute a 4f system, and the filtering aperture (4) is located on the frequency spectrum plane of the 4f system; The display screen (1) is used to display the vortex stripe light beam generated by the computer (10). The vortex stripe light beam serves as a light source and sequentially passes through the vortex focusing lens (2) and the filter aperture (4) before reaching the focusing lens (5). The light beam collimated by the focusing lens (5) serves as an incident vortex stripe light beam. The vortex focusing lens (2) is driven by rotating the rotating mirror frame (3), thereby obtaining incident vortex stripe light beams with different phase shifts. After being refracted by the object to be measured (6), the incident vortex stripe light beam is collected by the image acquisition module (8). By moving the first three-dimensional translation stage (7) and the second three-dimensional translation stage (9), a refraction intensity map of the object to be measured (6) appears on the image acquisition module (8) and is transmitted to the computer (10).

2. The phase measurement deflectometry wavefront measurement device based on vortex focusing lens according to claim 1, characterized in that: The vortex focusing lens (2) is a circular vortex focusing lens or an elliptical vortex focusing lens having a required topological charge.

3. The phase measurement deflectometry wavefront measurement device based on vortex focusing lens according to claim 1, characterized in that: The object to be measured (6) is a single lens or a combined lens.

4. The phase measurement deflectometry wavefront measurement device based on vortex focusing lens according to claim 1, characterized in that: The computer (10) controls the movement of the first three-dimensional translation stage (7) and the second three-dimensional translation stage (9) respectively.

5. A method for performing phase measurement deflectometry wavefront measurement using the measurement device according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: 1) turning on the display screen (1), and the vortex stripe light beam emitted by the display screen (1) is incident on the vortex focusing lens (2); Rotate the rotating mirror frame (3) to the following angles: Wherein, the positive integer N is the number of rotations of the rotating mirror frame, and N≥3, n=1,2,3...N, L is the topological charge of the vortex focusing lens (2), and incident vortex stripe light beams with different phase shifts are emitted from the focusing lens (5); The incident vortex stripe light beam is refracted by the object to be measured (6) and then emitted at a certain deflection angle to obtain a deformed vortex stripe light beam; The first three-dimensional translation stage (7) and the second three-dimensional translation stage (9) are moved, thereby driving the object to be measured (6) and the image acquisition module (8), so that a refraction intensity image I of the object to be measured (6) appears on the image acquisition module (8). n (x,y,θ n ), where (x, y) is the spatial coordinate distribution of the recording surface; The image acquisition module (8) respectively records the refraction intensity images I of the incident vortex stripe light beams with different phase shifts passing through the object to be measured (6). n (x,y,θ n ), and transmit the collected intensity data to the computer (10); 2) Based on the recorded multiple refraction intensity images I n (x,y,θ n ) calculates the phase distribution of the object to be measured (6) on the recording surface The formula is as follows: 3) Obtaining the real phase distribution of the object to be measured (6) by unwrapping operation Then, the optical inverse tracing method is used to obtain the wavefront slope distribution of the object to be measured (6), and the formula is as follows: Wherein, p is the fringe period, d is the distance from the object to be measured (6) to the image acquisition module (8), is the phase change of a pixel caused by the object to be measured (6), θ x and θ y are the light deflection angle components of the incident vortex stripe beam in the x direction and the y direction respectively; The wavefront slope W of the wavefront to be measured and the light deflection angle component θ x and θ y The relationship is as follows: In combination with the above relationship, the wavefront distribution of the object to be measured (6) can be obtained by numerically integrating the wavefront slope using a regional wavefront reconstruction algorithm.

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