Pentaprism scanning wavefront detection device and method based on pyramid interferogram

Abstract

The invention discloses a pentaprism scanning wavefront detection device and method based on a pyramid interferogram. The device comprises a guide rail, a pentaprism, a beam splitter prism, a plane spectroscope, a cube-corner prism, an imaging lens and a CCD camera. The method comprises the following steps: firstly, building a measuring light path in front of a to-be-measured wave surface, ensuring that a guide rail is parallel to the to-be-measured wave surface, and obtaining an interference pattern formed by a light beam reflected by a plane spectroscope and a light beam reflected by a cube-corner prism; then, the pitching and inclination angles of the plane spectroscope are adjusted, so that the number of fringes in an interferogram area is 20-50; then the guide rail is moved to scan the wavefront to be measured, and interferograms of the pentaprism at different positions are obtained; and finally, extracting inclination amounts of different positions of the measured wave surface from the interference pattern by using a fast Fourier transform (FFT) algorithm, and obtaining surface shape distribution of the measured wave surface through polynomial fitting. The device is simple in structure and low in cost, can accurately measure the emergent wave of the collimation system, and provides an effective basis for the adjustment of the collimation system.

Description

Technical Field

[0001] The present invention relates to the technical field of optical interference metrology, and in particular to a pentaprism scanning wavefront detection device and method based on a corner cube interference pattern. Background Art

[0002] With the development of fields such as optical processing, astronomical optics, and space optics, optical systems with larger apertures and higher precision have been increasingly widely used. To ensure the precision of an optical system, it is necessary to measure its output wavefront, and use the measurement results as the basis for quality evaluation, and then perform further processing or alignment until the optical system meets the precision requirements. Taking a digital wavefront interferometer as an example, if the collimated wavefront output by the interferometer is poor, it will lead to a large return error in the interference measurement results, which has a great impact on the detection and processing of optical elements. Therefore, it is crucial to detect the output wavefront of an optical system and perform system correction based on this.

[0003] The methods for wavefront detection mainly include the Hartmann method, the Shack - Hartmann method, the sub - aperture stitching method, the interference method, and the pentaprism scanning method. The Hartmann method uses an array aperture for wavefront sampling, and calculates the wavefront shape by measuring the wavefront slope at each sampling point. The principle is simple and the accuracy is relatively high, but the cost of a large - aperture Hartmann diaphragm is relatively high. The Shack - Hartmann method solves the full - aperture wave aberration of the measured system by measuring the difference between the centroid coordinates of the image spots formed by the distorted wavefront on the focal plane of the array lens and the centroid coordinates of the reference wavefront. Its accuracy is higher than that of the traditional Hartmann method, but it requires an array lens and a reference wavefront, and the system is relatively complex. The sub - aperture stitching method uses a small - aperture interferometer for sub - aperture stitching, which can expand the spatial measurement range and improve the spatial resolution. However, its mechanical structure is quite complex. If the mechanical structure is not properly controlled, the transmission error and cumulative error are very large, and the algorithm is difficult. The interference method has high accuracy and relatively simple algorithms, but it requires a standard wavefront with the same aperture as the measured wavefront as a reference, which is difficult to achieve when detecting optical systems with larger apertures.

[0004] The pentaprism scanning method utilizes the characteristic that a pentaprism deflects light by 90°, and tests the slope of the collimated wavefront of the system point by point, thereby realizing the measurement of the wavefront. The traditional pentaprism scanning method uses a lens to converge the wavefront beam deflected by the pentaprism, and determines the beam inclination angle through the position of the light spot at the focal plane of the lens, thereby realizing wavefront measurement. However, this method is more susceptible to the influence of focal plane positioning errors, and the centroid positioning accuracy of the light spot is not high. A pentaprism scanning scheme with higher accuracy requires a autocollimator for angle measurement. However, the autocollimator is expensive and requires the reflected light from the measured part as a reference to measure, and is not suitable for the detection of the output wavefront of the system. Summary of the Invention

[0005] The object of the present invention is to provide a pentaprism scanning wavefront detection device and method based on a corner-cube interference pattern, which has a simple structure, low cost and accurate results.

[0006] The technical solution for achieving the object of the present invention is: a pentaprism scanning wavefront detection device based on a corner-cube interference pattern, including a wavefront to be measured, a guide rail, a pentaprism, a beam splitter prism, a plane beam splitter, a corner-cube prism, an imaging lens and a CCD camera;

[0007] The light beam in a partial area on the wavefront to be measured is reflected by the pentaprism and turned by 90°, then passes through the beam splitter prism, and is split by the plane beam splitter. One path is reflected back to the beam splitter prism for reflection, and the other path is reflected by the corner-cube prism and then passes through the plane beam splitter again, and is transmitted to the beam splitter prism for reflection; the two reflected light beams form an interference pattern on the target surface of the CCD camera after passing through the imaging lens.

[0008] As a specific example, the wavefront to be measured is the wavefront emerging from the collimation system and is parallel to the guide rail.

[0009] As a specific example, the pentaprism is installed on the slider of the guide rail. One of the two faces with a 90° included angle is parallel to the wavefront to be measured, and the other faces the directions of the beam splitter prism, the plane beam splitter and the corner-cube prism; the two faces with a 45° included angle of the pentaprism are coated with a reflective film.

[0010] As a specific example, the beam splitting surface of the beam splitter prism forms a 45° included angle with the incident light beam, and is used to transmit and turn the light beam in the optical path.

[0011] As a specific example, the reflectivity of the plane beam splitter is about 50% to ensure that the light intensities of the two interfering light beams match each other, and the light beam participating in the interference is the light beam reflected by its working surface.

[0012] As a specific example, the corner-cube prism is fixed on a three-point self-centering holder, and the three-point self-centering holder is installed on a two-dimensional adjustment frame, which can ensure that the corner-cube prism can be adjusted in pitch and tilt; the corner-cube prism has three mutually perpendicular total reflection surfaces and one chord surface. The sides AB and AC of its cross-section are on the total reflection surfaces, and the side BC is on the chord surface. The light beam is reflected twice on the total reflection surfaces and then exits along the incident direction, serving as the test light beam, and forms an interference pattern with the reference light beam reflected by the plane beam splitter; the AB surface and AC surface of the corner-cube prism are total reflection surfaces.

[0013] As a specific example, the way of coating an antireflection film on the total reflection surface of the corner-cube prism can be adopted to generate a reflected light beam, eliminating the plane beam splitter, and directly using the reflected light beam of the BC surface reflected by the chord surface of the corner-cube prism and the reflected light beams reflected by the right-angle sides AB and AC for interference.

[0014] A pentaprism scanning wavefront detection method based on a corner-cube interference pattern includes the following steps:

[0015] Step 1: Set up a test optical path in front of the wavefront to be measured to obtain an interference pattern formed by the reflected beams of a plane beam splitter and a corner cube prism.

[0016] Step 2: Adjust the pitch and tilt angles of the plane beam splitter so that the number of fringes in the interference pattern region is 20 - 50.

[0017] Step 3: Move the pentaprism on the guide rail to scan the wavefront to be measured, and obtain the corner cube interference patterns corresponding to different regions of the measured wavefront. During the scanning process, keep the other optical elements in the optical path stationary.

[0018] Step 4: Use the fast Fourier transform (FFT) algorithm to extract the tilt amounts at different positions of the measured wavefront from the interference pattern, and obtain the surface shape distribution of the measured wavefront through polynomial fitting.

[0019] As a specific example, setting up the test optical path in front of the wavefront to be measured in Step 1 to obtain an interference pattern formed by the reflected beams of a plane beam splitter and a corner cube prism is as follows:

[0020] Step 1.1: Place the guide rail in front of the wavefront to be measured and ensure it is parallel to the wavefront to be measured.

[0021] Step 1.2: Fix the pentaprism on the slider of the guide rail so that the light of the wavefront to be measured is normally incident on one of the two faces of the pentaprism with an included angle of 90°. Then, place a beam splitter prism, a plane beam splitter, and a corner cube prism in sequence at one end of the guide rail opposite to the other face. Adjust the position and pose of the beam splitter prism so that the beam emerging from the pentaprism is incident on the beam splitting surface of the beam splitter prism at an angle of 45°. Adjust the plane beam splitter so that the beam transmitted by the beam splitter prism is normally incident on the working surface of the plane beam splitter.

[0022] Step 1.3: Place an imaging lens and a CCD camera in the emerging direction of the reflected beams of the corner cube prism and the plane beam splitter after being reflected by the beam splitter prism. Adjust the position and pose of the imaging lens and the CCD camera so that the light reflected by the beam splitter prism is normally incident on the imaging lens. Adjust the focal length of the imaging lens so that a clear interference pattern image is formed on the target surface of the CCD camera.

[0023] As a specific example, using the fast Fourier transform (FFT) algorithm to extract the tilt amounts at different positions of the measured wavefront from the interference pattern and obtain the surface shape distribution of the measured wavefront through polynomial fitting in Step 4 is as follows:

[0024] Step 4.1: Crop out a rectangular area with clear and complete fringes in the corner cube interference pattern, perform a fast Fourier transform on the cropped interference pattern to obtain the interference pattern spectrum, and use a high-pass filter to eliminate the zero-order spectrum. Then, locate the positive first-order spectrum by finding the maximum value, use a band-pass filter to extract the positive first-order spectrum, and perform an inverse Fourier transform on the positive first-order spectrum.

[0025] Step 4.2: Calculate the phase using the arctangent function. The calculation formula is as follows:

[0026]

[0027] where C(x, y) is the result of the inverse Fourier transform of the positive first-order spectrum, is the phase of the interferogram, with the unit of radian;

[0028] Step 4.3: Unwrap the phase of and use the unwrapped wavefront data as point cloud data for plane fitting to obtain the phase change amount of the fitted plane in the scanning direction of the pentaprism Through geometric relationship calculation, the tilt angle of the measured wavefront in the scanning area is obtained as:

[0029]

[0030] where λ is the wavelength of the measured wavefront, n is the number of pixels of the interferogram cropping area in the scanning direction, and a is the actual length corresponding to one pixel on the interferogram;

[0031] Step 4.4: Use the tilt data at different positions of the measured wavefront for derivative polynomial fitting to obtain the surface shape of the measured wavefront. Assume the surface shape distribution of the measured wavefront is W(x, y), and the scanning path of the pentaprism is l. Then the process of solving the wavefront polynomial coefficients is transformed into solving the following overdetermined equations:

[0032]

[0033] where p i (x, y) is the basis function of polynomial fitting, a i is the coefficient of p i (x, y), and α is the tilt angle of the measured wavefront in the scanning direction obtained using the interferogram. Let F(x, y; l) = tanα| l；x,y , According to the least square principle, the polynomial coefficients of the measured wavefront can be calculated by the following formula:

[0034]

[0035] The above formula is applicable to both one-dimensional polynomial fitting and two-dimensional polynomial fitting.

[0036] Compared with the prior art, the significant advantages of the present invention are as follows: (1) The pentaprism scanning wavefront detection device based on the corner-cube interference pattern of the present invention has a simple structure and convenient operation; (2) While ensuring the measurement accuracy, the cost is reduced, and it does not rely on the reflected light beam of the measured object for measurement; (3) The information directly obtained by the method in the present invention is the interference pattern rather than the wavefront focusing position in the traditional pentaprism scanning wavefront detection method. The wavefront is examined at the pupil plane position, which is more sensitive to the tilt change of the measured wavefront, the test result is more accurate, and it is not affected by the image plane position error. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 FIG. is a schematic structural diagram of a pentaprism scanning wavefront detection device based on the corner-cube interference pattern of the present invention.

[0038] Figure 2 FIG. is the processing effect diagram of the corner-cube interference pattern in the embodiment of the present invention, where (a) is the cropped corner-cube interference pattern, (b) is the corner-cube interference spectrum diagram, and (c) is the wavefront tilt component diagram extracted from the corner-cube interference pattern using the FFT algorithm.

[0039] Figure 3 FIG. is the calculated result curve diagram of the one-dimensional wavefront shape in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0040] The following further describes the present invention in detail with reference to the drawings and specific embodiments.

[0041] Combined with Figure 1 , a pentaprism scanning wavefront detection device based on the corner-cube interference pattern of the present invention includes a measured wavefront 1, a guide rail 2, a pentaprism 3, a beam splitter prism 4, a plane beam splitter 5, a corner-cube prism 6, an imaging lens 7, and a CCD camera 8;

[0042] The light beam in a partial area on the measured wavefront 1 is reflected by the pentaprism 3 and turned by 90°, then passes through the beam splitter prism 4, and is split by the plane beam splitter 5. One path is reflected back to the beam splitter prism 4 for reflection, and the other path is reflected by the corner-cube prism 6 and then passes through the plane beam splitter 5 again and is transmitted to the beam splitter prism 4 for reflection; the two reflected light beams form an interference pattern on the target surface of the CCD camera 8 after passing through the imaging lens 7.

[0043] As a specific example, the measured wavefront 1 is the wavefront emitted by the collimation system and is parallel to the guide rail 2.

[0044] As a specific example, the pentaprism 3 is installed on the slider of the guide rail 2. One of the two surfaces with a 90° angle is parallel to the measured wavefront 1, and the other faces the directions of the beam splitter prism 4, the plane beam splitter 5, and the corner-cube prism 6; the two surfaces with a 45° angle of the pentaprism 3 are coated with reflective films.

[0045] As a specific example, the splitting surface of the beam splitting prism 4 forms an angle of 45° with the incident light beam and is used to transmit and deflect light in the optical path.

[0046] As a specific example, the reflectivity of the plane beam splitter 5 is about 50% to ensure that the light intensities of the two interfering light beams match each other, and the light rays reflected by its working surface participate in the interference.

[0047] As a specific example, the corner cube prism 6 is fixed on a three-point self-centering holder, and the three-point self-centering holder is installed on a two-dimensional adjustment frame, which can ensure that the corner cube prism 6 can be adjusted in pitch and tilt; the corner cube prism (6) has three mutually perpendicular total reflection surfaces and one chord surface. The sides AB and AC of its cross-section are on the total reflection surfaces, and the side BC is on the chord surface. The light beam undergoes two reflections on the total reflection surfaces and then exits along the incident direction. As a test light beam, it forms an interference pattern with the reference light beam reflected by the plane beam splitter 5; the AB surface and AC surface of the corner cube prism 6 are total reflection surfaces.

[0048] As a specific example, a way of coating an antireflection film on the total reflection surfaces of the corner cube prism 6 can be adopted to generate a reflected light beam, eliminating the plane beam splitter 5, and directly using the reflected light beam from the BC surface of the chord surface reflection of the corner cube and the reflected light beams after reflection by the right-angle sides AB and AC for interference.

[0049] A pentaprism scanning wavefront detection method based on the corner cube interference pattern includes the following steps:

[0050] Step 1, Build a test optical path in front of the wavefront to be measured 1 to obtain an interference pattern formed by the reflected light beams of the plane beam splitter 5 and the corner cube prism 6;

[0051] Step 2, Adjust the pitch and tilt angles of the plane beam splitter 5 so that the number of fringes in the interference pattern area is 20 - 50;

[0052] Step 3, Move the pentaprism 3 on the guide rail 2 to scan the wavefront to be measured, and obtain the corner cube interference patterns corresponding to different regions of the measured wavefront 1. During the scanning process, keep the other optical elements in the optical path stationary;

[0053] Step 4, Use the fast Fourier transform FFT algorithm to extract the tilt amounts at different positions of the measured wavefront from the interference pattern, and obtain the surface shape distribution of the measured wavefront through polynomial fitting.

[0054] As a specific example, in Step 1, building a test optical path in front of the wavefront to be measured 1 to obtain an interference pattern formed by the reflected light beams of the plane beam splitter 5 and the corner cube prism 6 is specifically as follows:

[0055] Step 1.1, Place the guide rail 2 in front of the wavefront to be measured and ensure that it is parallel to the wavefront to be measured;

[0056] Step 1.2: Fix the pentaprism 3 on the slider of the guide rail 2, make the light of the wavefront to be measured incident normally on one of the two surfaces of the pentaprism 3 with an included angle of 90°, and sequentially place a beam splitter prism 4, a plane beam splitter 5 and a corner cube prism 6 at one end of the guide rail opposite to the other surface; adjust the position and pose of the beam splitter prism 4 to make the beam emerging from the pentaprism incident on the beam splitting surface of the beam splitter prism at an angle of 45°; adjust the plane beam splitter 5 to make the beam transmitted by the beam splitter prism 4 incident normally on the working surface of the plane beam splitter 5.

[0057] Step 1.3: Place an imaging lens 7 and a CCD camera 8 in the emerging direction of the reflected beam of the corner cube prism 6 and the plane beam splitter 5 after being reflected by the beam splitter prism 4, adjust the positions and poses of the imaging lens 7 and the CCD camera 8 to make the light reflected by the beam splitter prism 4 incident normally on the imaging lens 7; adjust the focal length of the imaging lens 7 to form a clear interference pattern image on the target surface of the CCD camera 8.

[0058] As a specific example, in step 4, the tilt amounts at different positions of the wavefront to be measured are extracted from the interference pattern by using the fast Fourier transform (FFT) algorithm, and the surface shape distribution of the wavefront to be measured is obtained by polynomial fitting, specifically as follows:

[0059] Step 4.1: Crop out a rectangular area with clear and complete fringes in the corner cube interference pattern, perform a fast Fourier transform on the cropped interference pattern to obtain the interference pattern spectrum, and use a high-pass filter to eliminate the zero-order spectrum; then locate the positive first-order spectrum by finding the maximum value, use a band-pass filter to extract the positive first-order spectrum, and perform an inverse Fourier transform on the positive first-order spectrum.

[0060] Step 4.2: Calculate the phase using the arctangent function, and the calculation formula is as follows:

[0061]

[0062] where \(C(x,y)\) is the result after the inverse Fourier transform of the positive first-order spectrum, is the phase of the interference pattern, with the unit of radian;

[0063] Step 4.3: Unwrap the phase of , take the unwrapped wavefront data as point cloud data for plane fitting, and obtain the phase change amount of the fitted plane in the scanning direction of the pentaprism. Through geometric relationship calculation, the tilt angle of the wavefront to be measured in the scanning area is obtained as:

[0064]

[0065] where \(\lambda\) is the wavelength of the wavefront to be measured 1, \(n\) is the number of pixels in the scanning direction of the cropped area of the interference pattern, and \(a\) is the actual length corresponding to one pixel on the interference pattern.

[0066] Step 4.4: Use the tilt data at different positions of the measured wavefront 1 to perform derivative polynomial fitting to obtain the surface shape of the measured wavefront 1. Assume the surface shape distribution of the measured wavefront 1 is W(x, y), and the scanning path of the pentaprism 3 is l. Then the process of solving the wavefront polynomial coefficients is transformed into solving the following overdetermined system of equations:

[0067]

[0068] where p i (x, y) is the basis function of polynomial fitting, and a i is the coefficient of p i (x, y), and α is the inclination angle of the measured wavefront in the scanning direction calculated using the interference pattern. Let F(x, y; l) = tanα| l；x,y , According to the least squares principle, the polynomial coefficients of the measured wavefront can be calculated by the following formula:

[0069]

[0070] The above formula is applicable to both one-dimensional and two-dimensional polynomial fittings.

[0071] The following further describes the present invention in detail with specific embodiments.

[0072] Embodiment 1

[0073] In this embodiment, the one-dimensional surface shape of the collimated wavefront of the ZYGO GPI interferometer is tested. The aperture of the measured wavefront is 100 mm, the wavelength λ = 633 nm, the CCD resolution is 1920×1200 pixels, the scanning sampling interval of the pentaprism is 2 mm, the aperture of the corner cube prism is 25.4 mm, and a rectangular area with a side length of about 15 mm at the center of the corner cube interference pattern is selected for wavefront slope calculation.

[0074] According to Figure 1 Set up the test optical path. Fix the pentaprism 3 on the slider of the guide rail 2, adjust the positions and poses of the pentaprism 3, the beam splitter prism 4, the plane beam splitter 5, the corner cube prism 6, the imaging lens 7 and the CCD camera 8, and obtain the corner cube interference pattern on the CCD camera 8. Adjust the focal length of the imaging lens 7 until the interference pattern is clear, and adjust the pitch and tilt of the plane beam splitter 5 until the number of fringes in the corner cube interference pattern is between 20 and 50. Move the slider of the guide rail 2 and collect the corner cube interference pattern every 2 mm, and record the area of the measured wavefront 1 corresponding to each frame of the interference pattern. During the measurement process, the relative position between the measurement device and the measured wavefront 1 should be kept unchanged. To avoid the influence of environmental vibration during the test, the test device should be preferably built on the same platform as the measured optical system. Once the measurement starts, all optical elements in the measurement device except the slider of the guide rail 2 and the pentaprism 3 should remain stationary. Attention should be paid to whether the components are firmly fixed when setting up the test optical path.

[0075] When cropping the rectangular area with clear and complete fringes in the corner cube interferogram, it should be ensured that the positions and sizes of the cropping areas of the corner cube interferograms corresponding to each scanning position are the same. Therefore, it is necessary to ensure that all the fringes of the corner cube interferograms within the determined cropping area are clear and complete. Considering that when the pentaprism 3 moves to the edge position of the measured wavefront 1, there may be missing fringes at the edge position of the corner cube interferogram. When determining the cropping area, the corner cube interferogram when the pentaprism 3 is located at the edge of the measured wavefront 1 should be mainly considered.

[0076] The cropped corner cube interferogram is as shown in Figure 2 (a) in the figure. Perform Fourier transform on the cropped corner cube interferogram to obtain its spectrum, as shown in Figure 2 (b) in the figure. Use a high-pass filter to eliminate the influence of the zero-order spectrum, then locate the positive first-order spectrum by finding the maximum value, extract the positive first-order spectrum through band-pass filtering and perform inverse Fourier transform on it, and then calculate the arctangent value of the result of the inverse Fourier transform of the positive first-order spectrum, and the phase distribution of the corner cube interferogram can be obtained. Unwrap the phase information and perform plane fitting to obtain the tilt information of the area of the measured wavefront corresponding to the corner cube interferogram, as shown in Figure 2 (c) in the figure.

[0077] Use the tilt data at different positions of the measured wavefront 1 for derivative polynomial fitting to obtain the surface shape of the measured wavefront 1 as shown in Figure 3 the figure. According to the calculation results, the PV of the measured wavefront 1 is 796.3 nm and the RMS is 256.50 nm.

[0078] In summary, the present invention provides a pentaprism scanning wavefront detection device and method based on a corner cube interferogram. By using the fast Fourier transform algorithm to obtain the slope information of the measured wavefront contained in the corner cube interferogram, the surface shape information of the output wavefront of the collimation system can be obtained. The structure of the present invention is simple and the operation is convenient. It examines the wavefront at the exit pupil plane position, is more sensitive to the tilt change of the measured wavefront, the test result is more accurate, and it is not affected by the image plane position error. While ensuring the measurement accuracy, the cost is greatly reduced, and it can meet the requirements of the output wavefront detection of the system in the optical workshop and scientific research.

Claims

1. A pentaprism scanning wavefront detection device based on a pyramid interference pattern, characterized in that: It comprises a wavefront to be measured (1), a guide rail (2), a pentaprism (3), a beam splitter (4), a plane beam splitter (5), a corner cube prism (6), an imaging lens (7) and a CCD camera (8); The light beam in a partial area on the wavefront to be measured (1) is reflected by a pentaprism (3), then deflected by 90 degrees and passes through a beam splitter (4), and then split by a plane beam splitter (5). One path is reflected back to the beam splitter (4) for reflection, and the other path is reflected by a corner cube prism (6), then passes through the plane beam splitter (5) again, and is transmitted to the beam splitter prism (4) for reflection; the two paths of reflected light beams pass through an imaging lens (7) to form an interference pattern on a target surface of a CCD camera (8).

2. The pentaprism scanning wavefront detection device based on the pyramid interference pattern according to claim 1, characterized in that: The wavefront (1) to be measured is an output wavefront of the collimation system and is parallel to the guide rail (2).

3. The pentaprism scanning wavefront detection device based on the pyramid interference pattern according to claim 1, characterized in that: The pentaprism (3) is mounted on a slider of a guide rail (2); one of the two surfaces of the pentaprism (3) at an angle of 90° is parallel to the wavefront (1) to be measured, and the other faces the direction of the beam splitter (4), the plane beam splitter (5) and the corner cube prism (6); and the two surfaces of the pentaprism (3) at an angle of 45° are coated with a reflective film.

4. The pentaprism scanning wavefront detection device based on the pyramid interference pattern according to claim 1, characterized in that: The beam splitting surface of the beam splitting prism (4) forms an angle of 45° with the incident light beam and is used for transmitting light and refracting light in the light path.

5. The pentaprism scanning wavefront detection device based on the pyramid interference pattern according to claim 1, characterized in that: The reflectivity of the plane beam splitter (5) is 50%, which ensures that the light intensities of the two interference light beams match each other, and the light participating in the interference is the light reflected by the working surface.

6. The pentaprism scanning wavefront detection device based on the pyramid interference pattern according to claim 1, characterized in that: The corner cube prism (6) is fixed on a three-point self-centering clamp, and the three-point self-centering clamp is installed on a two-dimensional adjustment frame, so that the pitch and tilt of the corner cube prism (6) can be adjusted; the corner cube prism (6) has three mutually perpendicular total reflection surfaces and a chord surface, the sides AB and AC of the cross section are on the total reflection surfaces, and the side BC is on the chord surface. After the light beam is reflected twice on the total reflection surface, it is emitted along the incident direction and serves as a test light beam, which forms an interference pattern with the reference light beam reflected by the plane beam splitter (5).

7. The pentaprism scanning wavefront detection device based on the pyramid interference pattern according to claim 6, characterized in that: A reflected light path can be generated by coating the total reflection surface of the corner cube prism (6) with an anti-reflection film, eliminating the plane beam splitter (5), and directly using the corner cube chord surface to reflect the reflected light beam on the BC surface and the reflected light beam after being reflected by the right-angle sides AB and AC to interfere.

8. A pentaprism scanning wavefront detection method based on pyramid interference pattern, characterized in that: The following steps are involved: Step 1, constructing a test optical path in front of the wavefront to be measured (1), and obtaining an interference pattern formed by the light beams reflected by the plane beam splitter (5) and the corner cube prism (6); Step 2, adjusting the pitch and tilt angles of the plane beam splitter (5) so that the number of fringes in the interference pattern area is 20 to 50; Step 3, moving the pentaprism (3) on the guide rail (2) to scan the wavefront to be measured, obtaining the cone interference patterns corresponding to different regions of the wavefront to be measured (1), and keeping the other optical elements in the optical path stationary during the scanning process; Step 4: Use the Fast Fourier Transform (FFT) algorithm to extract the tilt of the measured wavefront at different positions from the interference pattern, and obtain the surface shape distribution of the measured wavefront through polynomial fitting.

9. The pentaprism scanning wavefront detection method based on the pyramid interference pattern according to claim 7, characterized in that: In step 1, a test optical path is constructed in front of the wavefront to be measured (1), and an interference pattern formed by the reflected light beams of the plane beam splitter (5) and the corner cube prism (6) is obtained, as follows: Step 1.1, place the guide rail (2) in front of the wavefront to be measured and ensure that it is parallel to the wavefront to be measured; Step 1.2, fix the pentaprism (3) on the slider of the guide rail (2) so that the wavefront light to be measured is incident on one of the two faces of the pentaprism (3) with an angle of 90°, and place a beam splitter prism (4), a plane beam splitter (5) and a corner cube prism (6) in sequence at one end of the guide rail directly opposite the other face; adjust the position and posture of the beam splitter prism (4) so ​​that the output light beam of the pentaprism is incident on the beam splitting surface of the beam splitter prism at 45°; adjust the plane beam splitter (5) so that the transmitted light beam of the beam splitter prism (4) is incident on the working surface of the plane beam splitter (5); Step 1.3, placing an imaging lens (7) and a CCD camera (8) in the direction of the light beam reflected by the corner cube prism (6) and the plane beam splitter (5) after being reflected by the beam splitter prism (4), adjusting the position and posture of the imaging lens (7) and the CCD camera (8) so that the light reflected by the beam splitter prism (4) is incident on the imaging lens (7); adjusting the focal length of the imaging lens (7) so that a clear interference pattern is formed on the target surface of the CCD camera (8).

10. The pentaprism scanning wavefront detection method based on the pyramid interference pattern according to claim 7, characterized in that: In step 4, the fast Fourier transform (FFT) algorithm is used to extract the tilt of the measured wavefront at different positions from the interference pattern, and the surface shape distribution of the measured wavefront is obtained by polynomial fitting, as follows: Step 4.1, crop a rectangular area with clear and complete fringes in the pyramid interference pattern, perform fast Fourier transform on the cropped interference pattern to obtain the interference pattern spectrum, and use a high-pass filter to eliminate the zero-order spectrum; then locate the positive first-order spectrum by finding the maximum value, use a bandpass filter to extract the positive first-order spectrum, and perform inverse Fourier transform on the positive first-order spectrum; Step 4.2, use the inverse tangent function to calculate the phase, the calculation formula is as follows: Among them, C(x,y) is the result of the inverse Fourier transform of the positive first-order spectrum, is the interference pattern phase, in radians; Step 4.3: Perform phase unwrapping, use the unwrapped wavefront data as point cloud data for plane fitting, and obtain the phase change of the plane in the scanning direction of the pentaprism after fitting Through geometric calculation, the inclination angle of the measured wavefront in the scanning area is obtained as follows: Wherein, λ is the wavelength of the measured wavefront (1), n ​​is the number of pixels in the interferogram cropping area in the scanning direction, and a is the actual length corresponding to one pixel on the interferogram; Step 4.4, using the tilt data of the measured wavefront (1) at different positions to perform derivative polynomial fitting, the surface shape of the measured wavefront (1) is obtained; the surface shape distribution of the measured wavefront (1) is set to W (x, y), and the scanning path of the pentaprism (3) is set to l, then the process of solving the wavefront polynomial coefficients is transformed into solving the following overdetermined equations: Among them, p i (x, y) is the basis function of the polynomial fitting, a i For p i (x, y) coefficient, α is the inclination angle of the measured wavefront in the scanning direction calculated using the interference pattern; let F(x, y; l) = tanα| l；x,y , According to the least squares principle, the polynomial coefficients of the measured wavefront are calculated by the following formula: A=G -1 F, where The above formula is applicable to both one-dimensional polynomial fitting and two-dimensional polynomial fitting.

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