Optical synthetic aperture coarse-fine two-stage co-phase error detection method

Abstract

The invention provides an optical synthetic aperture coarse-fine two-stage co-phase error detection method, and the method comprises the steps: carrying out the processing of every two apertures in the optical synthetic aperture: enabling two beams of light passing through the two apertures to sequentially pass through two reflectors and a Mach-Zehnder type light combination interference system, and then reflecting three parts of light beams, the light beams are sequentially marked as first light beams, second light beams and third light beams; wherein the third beam of light is four paths of signals A, B, C and D of which the phase difference interval is pi / 2; performing tilt error detection and correction by using the first light beam; performing translation error detection by using the second light beam through a dispersion fringe method; coarse correction of translation errors is carried out; respectively dividing four paths of signals A, B, C and D into two wave bands, carrying out signal acquisition, detecting translation errors through stripes, and carrying out fine correction on the translation errors; the coarse and fine detection and correction of the tilt error and the translation error are continuously and alternately carried out until the co-phase requirement under the detection precision is realized.

Description

Technical Field

[0001] The present invention relates to a coarse and fine two-stage common phase error detection method for optical synthetic aperture, in particular to high frequency common phase error detection combining a coarse common phase mode based on a dispersion fringe detection method with a fine common phase mode based on an ABCD sampling detection method. Background Art

[0002] In the field of astronomy, the angular resolution of conventional single-aperture telescopes cannot meet the observation of most stellar sources and other celestial bodies of interest. Increasing the aperture to improve the angular resolution is constrained by many factors, such as processing technology, supporting structure, materials and operating costs. In this context, a major progress in resolving this contradiction is to shift from single telescope observation to a sparse array composed of two or more telescopes, adjusting the spacing between sub-telescopes according to scientific needs, and obtaining observation capabilities far higher than the angular resolution of a single sub-telescope. This technology is called optical synthetic aperture.

[0003] Phase control is the key to achieving high-resolution imaging with optical synthetic aperture. If high-precision common phase error detection and correction between telescopes cannot be achieved, then synthetic aperture will be meaningless. Any optical synthetic aperture system should consider a common phase subsystem for subaperture low-order aberration (translation error and tilt error) detection and correction. The common phase system has three main requirements for error detection, namely high frequency, wide range and high precision.

[0004] The existing common phase detection technology can be divided into three categories: focal plane detection, pupil plane detection and far-field analysis: the focal plane detection method is to measure the corresponding translation error based on the focal plane and quasi-focal plane images of the telescope through the corresponding calculation method; pupil plane detection means that the entrance pupil of the detector receives the pupil plane light of the telescope, and produces an image modulated by the translation error through related optical phenomena, and then obtains the corresponding translation error from these image information; far-field analysis is to use the far-field image of the telescope and use the corresponding algorithm to calculate the size of the translation error index to achieve the detection of translation error. Because the pupil plane detection method has high accuracy and can achieve a larger range and higher detection rate, the pupil plane detection method is currently widely used in telescopes that are currently in existence or under construction. The focal plane detection method is only used in situations where the rate and detection range are low.

[0005] In the pupil detection method, the method based on Shack-Hartmann wavefront detection uses broadband diffraction and narrowband diffraction respectively. Li Bin, "Experimental Study on Active Common Phase of Spliced ​​Mirrors", Journal of Photonics; Zhang Yongfeng, "The Influence of Gap and Mask Eccentricity on Common Phase of Spliced ​​Mirrors Using Ideal Template Narrowband Algorithm", Progress in Laser and Optoelectronics, achieved a detection accuracy of 60nm and 6nm within the detection range of ±30μm and ±0.1μm; Zhu Nenghong, "Using a Four-Pyramid Sensor to Detect the Normal Path Difference of Optical Spliced ​​Mirrors", the medium four-pyramid detection method based on the four-pyramid wavefront sensor achieved a detection accuracy of 5.7nm within a wavelength range; the dispersion fringe sensing method has been successfully used in the James Webb Telescope for coarse-precision common phase due to its high frequency and wide range detection advantages. The Large Magellan Telescope under construction has made improvements to this method in 2022 to enable it to face the future seven-aperture common phase. However, the existing common phase error detection methods have the following shortcomings:

[0006] (1) When detecting translation errors, the tilt errors of the two sub-apertures must have been properly corrected. However, the above method cannot detect tilt errors. Therefore, other co-phasing methods generally used for tilt error correction use alternating co-phasing.

[0007] (2) Synthetic aperture translation error detection requires a detection range of tens of microns and a detection accuracy of nanometers. The existing single measurement method cannot guarantee such a large range and high precision at the same time. The broadband light source detection method has a large detection range, but when detecting a large range, the detection time is too long and the accuracy is low; the narrowband light source detection accuracy is high, but there is a 2π ambiguity phenomenon in the detection range, and the detection range cannot exceed half the wavelength of the quasi-monochromatic light being detected.

[0008] (3) For the wide-band light beam passing through the synthetic aperture, the existing detection method has a low detection frequency and a very narrow light energy bandwidth (10nm bandwidth), resulting in too low target flow rate. In addition, it is greatly affected by factors such as beam dispersion and noise. The low signal-to-noise ratio will seriously affect the accuracy of the detection algorithm. Summary of the invention

[0009] The technical problem solved by the present invention is: to overcome the above shortcomings, to detect the errors in the entire common phase process by combining multiple detection methods, to provide an optical synthetic aperture coarse and fine two-stage common phase error detection method, to solve the problem that the existing methods cannot take into account the high frequency, large range and high precision of common phase error detection.

[0010] The technical solution of the present invention is: a method for detecting coarse and fine two-stage common phase errors of optical synthetic apertures, and the following processing is performed for each two apertures in the optical synthetic aperture:

[0011] The two beams of light passing through the two apertures are reflected by two beam splitters and a Mach-Zehnder light combining interference system, and then three partial beams are recorded as the first beam, the second beam and the third beam respectively; the third beam is four signals of A, B, C and D with a phase difference interval of π / 2;

[0012] Using the first light beam to detect the tilt error, and adjusting the tilt error by adjusting the swing mirror in front of the two light beams;

[0013] The second light beam is used to detect the translation error by using the dispersion fringe method to obtain a rough translation error; and the error is roughly corrected by adjusting the K mirror group through the optical path difference in front of the swing mirror;

[0014] The four signals A, B, C, and D are each divided into two bands, and the signals are collected, and the translation error is detected by fringes to obtain a high-precision translation error and the optical path difference is used to adjust the K mirror group to perform precise correction of the translation error;

[0015] The coarse and fine detection and correction of the above-mentioned tilt error and translation error are continuously performed alternately until the common phase requirement under the detection accuracy is achieved.

[0016] Preferably, the consistency adjustment of the optical path and the pointing direction of the two apertures is achieved through the coarse and fine common phase error detection of the pointing detection; the Mach-Zehnder type light combining interference system includes 4 plane reflectors, 2 wedge-shaped beam splitters I, and 1 wedge-shaped beam splitter II; two parallel light beams are incident on the two wedge-shaped beam splitters I and are split into 4 light paths, which are respectively reflected by the two plane reflectors to the wedge-shaped beam splitter II for the second beam splitting and beam combining, and 4 light paths are output, each of which is formed by double-aperture light combining, and the optical path difference of the two combined light beams on the output side with the same direction as the incident light is zero, while the optical path difference of the two combined light beams on the other side is π, and the piezoelectric displacement stage of the wedge-shaped beam splitter I on the other side is fine-tuned to increase the phase of the reflected light beam by π / 2 at the specified wavelength, so that the optical path differences of the output 4 light paths are 0, π / 2, π, and 3π / 2, respectively, and the ABCD four-phase signal acquisition can be achieved.

[0017] Preferably, the wedge-shaped beam splitter I and the wedge-shaped beam splitter II adopt a thickened trapezoidal mirror blank, and the thickened trapezoidal mirror blank allows the secondary reflected light of the incident light on the reverse side to return to the side of the mirror blank, and the side is a right-angled trapezoid. The transmitted light beam of the secondary reflected light on the side will form an angle with the main reflected light, and the reflected light beam of the secondary reflected light on the side will be emitted from the other side of the mirror blank, effectively avoiding the interference of stray light on the main light path.

[0018] Preferably, wedge-shaped beam splitter I is used for splitting the incident light, which is equivalent to a single-beam beam splitter, with a semi-transparent and semi-reflective film on the upper surface and an anti-reflective film on the lower surface. When the light beam is incident from the upper surface, 50% of the light beam is reflected, and 50% of the light is transmitted, and the transmitted light beam is finally emitted from the lower surface; wedge-shaped beam splitter II is used for combining two light beams, which is equivalent to a double-beam beam combiner, with a semi-transparent and semi-reflective film on the upper surface and an anti-reflective film on the lower surface. When the light beam is incident from the upper surface, 50% of the light beam is reflected, and 50% of the light is transmitted, and the transmitted light beam is finally emitted from the lower surface. The beam splitter materials are all made of quartz glass.

[0019] Preferably, detecting the translation error by fringes comprises:

[0020] Scan the interference fringes formed by the two-aperture light beams, and select the light intensity of four points with a phase interval of π / 2 as the four original estimation parameters A, B, C, and D, where A represents the point where the light intensity rises, B represents the point where the light intensity is maximum, C represents the point where the light intensity falls, and D represents the point where the light intensity is minimum. Based on these four original parameters, the current light intensity, contrast V, and fringe phase φ of the interference fringes are estimated;

[0021] Calculate the fringe contrast. When the contrast exceeds the threshold, it means that interference fringes appear, and the next step is to calculate the translation error; otherwise, the previous level of dispersion fringe method is used for rough measurement and adjustment;

[0022] Calculate the translation error: divide the four signals A, B, C, and D into two bands respectively, and invert the translation error using the fringe phase difference between the two bands.

[0023] Preferably, the current light intensity N, contrast V and fringe phase φ of the interference fringe are expressed as

[0024] N=A+B+C+D

[0025]

[0026] An optical synthetic aperture coarse and fine two-stage common phase error detection system, comprising a beam splitter group D1, a beam splitter group D2, a spacing adjustment mirror group, a pointing detection system, a dispersion fringe sensing system, a Mach-Zehnder type light combining interference system, and a control system;

[0027] The beam splitter group D1 and the beam splitter group D2 are used to reflect the two sub-beams to the pointing detection system, and the beam passing through the beam splitter group D1 is transmitted to the spacing adjustment mirror group, and the spacing adjustment mirror group adjusts the optical axis spacing of the two sub-beams and then transmits them to the dispersion fringe sensing system;

[0028] The light beam passing through the beam splitter group D2 is input into the Mach-Zehnder type light combining interferometer system;

[0029] The pointing detection system is used to calculate the tilt error and send the tilt error to the control system;

[0030] The dispersion fringe sensing system is used to achieve coarse precision detection of translation error, and send the detected coarse precision translation error to the control system;

[0031] The Mach-Zehnder light combining interference system is used to form four signals A, B, C, and D with a phase difference interval of π / 2, and detect the translation error through fringes, and send the obtained high-precision translation error to the control system;

[0032] The control system corrects the error corresponding to the optical synthetic aperture in real time according to the received tilt error, coarse-precision translation error, and high-precision translation error.

[0033] Preferably, the Mach-Zehnder type light combining interference system includes 4 plane reflectors, 2 wedge-shaped beam splitters I, and 1 wedge-shaped beam splitter II; two parallel light beams are incident on the two wedge-shaped beam splitters I and are split into 4 light beams, which are respectively reflected by the two plane reflectors to the wedge-shaped beam splitter II for a second beam splitting and beam combining, and 4 light beams are output, each of which is formed by double-aperture light combining, and the optical path difference of the two combined light beams on the output side with the same direction as the incident light is zero, while the optical path difference of the two combined light beams on the other side is π, and the piezoelectric displacement stage of the wedge-shaped beam splitter I on the other side is fine-tuned to increase the phase of the reflected light beam by π / 2 at a specified wavelength, so that the optical path differences of the output 4 light beams are 0, π / 2, π, and 3π / 2, respectively, thereby realizing the acquisition of ABCD four-phase signals.

[0034] Preferably, detecting the translation error by fringes comprises:

[0035] Scan the interference fringes formed by the two-aperture light beams, and select the light intensity of four points with a phase interval of π / 2 as the four original estimation parameters A, B, C, and D, where A represents the point where the light intensity rises, B represents the point where the light intensity is maximum, C represents the point where the light intensity falls, and D represents the point where the light intensity is minimum. Based on these four original parameters, the current light intensity N, contrast V, and fringe phase φ of the interference fringes are estimated;

[0036] Calculate the fringe contrast. When the contrast exceeds the threshold, it means interference fringes appear, and the next step is to calculate the translation error. Otherwise, perform the dispersion fringe method rough measurement and adjustment again.

[0037] Calculate the translation error: divide the four signals A, B, C, and D into two bands respectively, and invert the translation error using the fringe phase difference between the two bands.

[0038] Preferably, the control system includes an optical path difference adjustment K mirror and an optical axis adjustment swing mirror installed on both sub-beams; the optical axis adjustment swing mirror is used to adjust and correct the tilt error; the optical path difference adjustment K mirror is used to correct the translation error.

[0039] The beneficial effects of the present invention compared with the prior art are:

[0040] (1) The combination of multiple detection methods can not only realize the complementary detection and correction of tilt error and translation error, but also improve the detection range of the common phase system, so that the common phase system can take into account both detection range and accuracy.

[0041] (2) Both the dispersion fringe sensing method and the ABCD sampling detection method have the characteristics of high-frequency detection. The coupling of these two common phase methods can ensure the high-frequency detection requirements of the two-stage closed loop.

[0042] (3) The ABCD sampling detection method can be used for common phase detection in a wide spectrum through a special MZ beam combining optical path design. It is insensitive to noise interference and can stably achieve high-precision common phase error detection even under low signal-to-noise ratio conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Flow chart of the coarse and fine two-stage common phase error detection scheme for optical synthetic aperture;

[0044] Figure 2 Dispersion fringe sensor structure and its zemax simulation;

[0045] Figure 3 Dispersion fringe sensor detector captures fringe and zemax simulates image plane dispersion fringe;

[0046] Figure 4 The main peak displacement extraction method extracts the interference information of the dispersion fringe image at different wavelengths;

[0047] Figure 5 (a) Structure of Mach-Zehnder light-combining interferometer system (b) Phase jump analysis diagram;

[0048] Figure 6 (a) Simple flat plate design of beam splitter (b) Thickened trapezoidal mirror blank structure (c) Schematic diagram of the specific structure. DETAILED DESCRIPTION

[0049] The present invention will be further described below in conjunction with the embodiments.

[0050] In the process of detecting and correcting the high-precision common phase error between optical synthetic aperture telescopes, due to the large dynamic range of displacement error, there is currently no good optical method that can take into account the detection range, measurement accuracy and detection frequency at the same time, and the tilt error must be considered in real time during the common phase process. Therefore, the present invention divides the common phase error detection into several stages: tilt error detection and rough and precise measurement of translation error, and different detection methods are used in different stages.

[0051] The specific methods include tilt error detection, coarse common phase detection and fine common phase detection. Taking the common phase error detection between two apertures as an example, when common phase is detected, the tilt error should be detected and corrected first, and then the translation error should be detected and corrected in stages from coarse to fine. The detection and correction of tilt and translation errors should be carried out alternately until the common phase requirement under the detection accuracy is achieved. The closed-loop control is finally used to stabilize the common phase state in real time.

[0052] like Figure 1 As shown, the collimator emits two sub-beams to simulate two sub-apertures. The two sub-beams reflect part of the wavelength of the beam to the pointing detection module through the beam splitter group D1 and the beam splitter group D2, and feed back the measurement results to the control system. The tilt error is corrected by adjusting the optical axis adjustment swing mirror; then they enter the dispersion fringe sensing system through the sub-beam spacing adjustment mirror group to perform a rough common phase mode translation error detection, and feed back the measurement results to the control system (optical path difference adjustment K mirror, optical axis adjustment swing mirror), and the common phase error is roughly corrected by adjusting the optical path difference adjustment K mirror; the two sub-beams reflected by the beam splitter group D1 finally enter the Mach-Zehnder type light combining interference system, and the translation error detection of the fine common phase mode is completed through the ABCD fringe detection method. The common phase detection includes the following steps:

[0053] (1) The two sub-beams pass through the beam splitter group D1 and the beam splitter group D2 and enter the pointing detection system, where the tilt error is corrected using the pointing detection method. The two sub-beams are converged to the detection camera respectively, the tilt error is calculated using the centroid extraction method, and the optical axis is adjusted to adjust the swing mirror for correction;

[0054] (2) The two sub-beams pass through the spacing adjustment mirror group and enter the coarse common phase mode translation error detection system, and the coarse precision detection of the translation error is realized by the dispersion fringe method.

[0055] The core components of the dispersion fringe sensing system include interference aperture, dispersion element, imaging lens and CCD camera, which spatially demodulates the information carried by different wavelengths to produce Figure 3 The spiral intensity distribution diagram shown: the change of light intensity of each wavelength in the interference direction follows the double-slit interference law. In the dispersion direction, the light intensity fluctuates due to the different effects of translation error on different wavelengths. The combined effect of interference and dispersion forms dispersion fringes on the image plane.

[0056] Since the translation error detection of a single-wavelength light source has a 2π uncertainty when it is greater than one wavelength, the present invention selects a continuous wide-spectrum light source to overcome the 2π ambiguity and improve the detection accuracy at the same time.

[0057] Based on the intensity distribution of the dispersion fringes generated on the sensor image plane, the main peak displacement extraction method is selected, such as Figure 4As shown, by analyzing the interference direction of the dispersion fringes, the translation error can be calculated through the approximate linear change of the main peak displacement and the translation error in the interference direction, and the algorithm can achieve a common phase accuracy higher than a quarter wavelength, meeting the initial coarse common phase requirement of the synthetic aperture.

[0058] (3) The two sub-beams reflected by the beam splitter group D1 finally enter the Mach-Zehnder type light combining interference system. The four emitted beams just constitute four signals A, B, C, and D with a phase difference interval of π / 2, and the precise common phase is achieved through the ABCD sampling detection method. The specific implementation steps are:

[0059] (3.1) The Mach-Zehnder type light combining interference system designed by the present invention. Its optical path design is as follows Figure 5 As shown in (a), it includes 2 50.8mm plane mirrors, 2 small trapezoidal beamsplitters (wedge-shaped beamsplitters), 1 large trapezoidal beamsplitter (wedge-shaped beamsplitter), and 2 25.4mm mirrors. Two parallel light beams are incident on the small trapezoidal beamsplitter and split into 4 light paths. They are reflected by the 50.8mm aperture mirror to the large trapezoidal beamsplitter for the second beam splitting and beam combining, and 4 light paths are output. Each light path is a double-aperture photosynthesis beam. At the last trapezoidal beamsplitter, a constructive output side and a destructive output side are generated. The reflection surface causes the phase difference of the light on both sides to be different. The phase mutation analysis is shown in the figure. Figure 5 As shown in (b). The arrow indicates the polarization phase of the p light, the dotted circle and the forked circle indicate the polarization phase of the s light, and the splitting surface is the working surface where the short side of the trapezoid is located. In order to reduce the differential polarization effect between the two arms and achieve a good balance between the s and p polarizations, the incident angle is designed to be 30°. At this time, the incident angle is smaller than the Brewster angle. Therefore, when the light is incident from the optically sparse medium to the optically dense medium, the reflected s light has a phase mutation of Π, and the p light has no phase mutation; when the light is incident from the optically dense medium to the optically sparse medium, the reflected s light has no phase mutation, and the p light has a phase mutation of Π. Assuming that the optical path difference of the incident light of the module is zero, this results in the two combined light beams on the output side with the same direction as the incident light ( Figure 5 (b) The optical path difference between 1 and 2) is zero, while the two combined beams ( Figure 5 The optical path difference between 3 and 4 in (b) is π. Then, by fine-tuning the piezoelectric displacement stage of the small trapezoidal beam splitter to change the position of the beam splitter, the optical path difference between outputs 2 and 4 is increased, so that the optical path differences of output ports 1, 2, 3, and 4 are 0, π / 2, π, and 3π / 2 respectively, and the acquisition of the four-phase ABCD signals can be realized.

[0060] (3.2) Wedge-shaped beam splitter design. Considering that if the beam splitter blank is made of Figure 6 In the simple flat plate design shown in (a), the emission direction of the stray light will be parallel to the main light path, thus interfering with the interference light path. Figure 6The thickened trapezoidal mirror blank shown in (b) is characterized by reducing the size of the incident surface and increasing the thickness of the mirror blank, so that the secondary reflected light on the back side will not return to the front side, but will return to the side of the mirror blank. At this time, due to the trapezoidal design of the side, the transmitted light beam of the secondary reflected light on the side will form a larger angle with the main reflected light, and the reflected light beam of the secondary reflected light on the side will be emitted from the other side of the mirror blank, which can effectively avoid the interference of stray light on the main light path. The specific design is as follows Figure 6 (c) Small right-angle trapezoidal prism is mainly used for incident light beam splitting, which is equivalent to a single beam splitter. The length and width of its upper surface are 11mm and 10mm respectively, the length and width of its lower surface are 20mm and 10mm respectively, and the thickness is 10mm. The upper surface is coated with a semi-transparent and semi-reflective film, and the lower surface is coated with an anti-reflective film. When the light beam is incident from the upper surface, 50% of the light beam is reflected, and 50% of the light is transmitted, and the transmitted light beam is finally emitted from the lower surface; Large right-angle trapezoidal prism is mainly used for double-beam beam combining, which is equivalent to a double-beam beam combiner. The length and width of its upper surface are 55mm and 10mm respectively, the length and width of its lower surface are 70mm and 10mm respectively, and the thickness is 10mm. The upper surface is coated with a semi-transparent and semi-reflective film, and the lower surface is coated with an anti-reflective film. When the light beam is incident from the upper surface, 50% of the light beam is reflected, and 50% of the light is transmitted, and the transmitted light beam is finally emitted from the lower surface. The material of the right-angle trapezoidal prism is quartz glass.

[0061] (3.3) Output signal acquisition. Since the Mach-Zehnder beam combining optical path has a special configuration with high symmetry, it can ensure that the two interference beams have the same intensity. The two aperture beams pass through this system, and the phase is modulated by static optical elements to generate four combined beams with known phase separation. The phase difference interval of the four output beams is exactly π / 2. The four signals A, B, C, and D are each divided into two bands, and 8 single-point detectors are used for signal acquisition.

[0062] (3.4) ABCD algorithm solution. When scanning the interference fringes formed by two-aperture light beams, the light intensity of four points with a phase interval of π / 2 is selected as the four original estimated parameters A, B, C, and D, where A represents the light intensity rising point (Ascending), B represents the light intensity maximum point (Bright), C represents the light intensity falling point (desCending), and D represents the light intensity minimum point (Dark). The current light intensity, contrast, and fringe phase of the interference fringes can be estimated based on these four original parameters. The Mach-Zehnder beam combiner in the present invention outputs exactly four signals A, B, C, and D. The measured parameters can be expressed as

[0063]

[0064] When the fringe contrast V exceeds the threshold, it means that interference fringes appear, and the translation error can be calculated. If it does not reach the threshold, the coarse common phase error detection of the dispersion fringe method is re-performed and adjusted.

[0065] (3.5) Calculate the translation error. Since a single wavelength will have the problem of integer ambiguity, two bands are used for ABCD sampling detection. The translation error is inverted by the fringe phase difference of the two bands. The accuracy of the fine common phase can reach λ / 20.

[0066] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0067] Parts not described in detail in the present invention belong to common knowledge of those skilled in the art.

Claims

1. A method for detecting coarse and fine common phase errors of optical synthetic aperture, characterized in that : Perform the following processing for each two apertures in the optical synthetic aperture: The two beams of light passing through the two apertures are reflected by two beam splitters and a Mach-Zehnder light combining interference system, and then three partial beams are recorded as the first beam, the second beam and the third beam respectively; the third beam is four signals of A, B, C and D with a phase difference interval of π / 2; Using the first light beam to detect the tilt error, and adjusting the tilt error by adjusting the swing mirror in front of the two light beams; The second light beam is used to detect the translation error by using the dispersion fringe method to obtain a rough translation error; and the error is roughly corrected by adjusting the K mirror group through the optical path difference in front of the swing mirror; The four signals A, B, C, and D are each divided into two bands, and the signals are collected, and the translation error is detected by fringes to obtain a high-precision translation error and the optical path difference is used to adjust the K mirror group to perform precise correction of the translation error; The coarse and fine detection and correction of the above-mentioned tilt error and translation error are continuously performed alternately until the common phase requirement under the detection accuracy is achieved.

2. The method according to claim 1, characterized in that: The Mach-Zehnder light combining interference system comprises four plane reflectors, two wedge-shaped beam splitters I and one wedge-shaped beam splitter II; two parallel light beams are incident on the two wedge-shaped beam splitters I and are split into four light beams, which are respectively reflected by two plane reflectors to the wedge-shaped beam splitter II for a second beam splitting and beam combining, and four light beams are output, each of which is formed by double-aperture light combining, the optical path difference of the two combined light beams on the output side with the same direction as the incident light is zero, and the optical path difference of the two combined light beams on the other side is π, and the piezoelectric displacement stage of the wedge-shaped beam splitter I on the other side is fine-tuned to increase the phase of the reflected light beam by π / 2 at a specified wavelength, so that the optical path differences of the output four light beams are 0, π / 2, π, and 3π / 2, respectively, so that the ABCD four-phase signal acquisition can be realized.

3. The method according to claim 2, characterized in that: The wedge-shaped beam splitter I and the wedge-shaped beam splitter II adopt a thickened trapezoidal mirror blank. The thickened trapezoidal mirror blank allows the secondary reflected light of the incident light on the reverse side to return to the side of the mirror blank. The side is a right-angled trapezoid. The transmitted light beam of the secondary reflected light on the side will form an angle with the main reflected light, and the reflected light beam of the secondary reflected light on the side will be emitted from the other side of the mirror blank, effectively avoiding the interference of stray light on the main light path.

4. The method according to claim 3, characterized in that: Wedge-shaped beam splitter I is used for incident light beam splitting, which is equivalent to a single-beam beam splitter. The upper surface is coated with a semi-transparent and semi-reflective film, and the lower surface is coated with an anti-reflection film. When the light beam is incident from the upper surface, 50% of the light beam is reflected, and 50% of the light is transmitted, and the transmitted light beam is finally emitted from the lower surface; wedge-shaped beam splitter II is used for double-beam beam combining, which is equivalent to a double-beam beam combiner. The upper surface is coated with a semi-transparent and semi-reflective film, and the lower surface is coated with an anti-reflection film. When the light beam is incident from the upper surface, 50% of the light beam is reflected, and 50% of the light is transmitted, and the transmitted light beam is finally emitted from the lower surface. The beam splitter material is quartz glass.

5. The method according to claim 2, characterized in that: The detecting translation error by fringes comprises: Scan the interference fringes formed by the two-aperture light beams, and select the light intensity of four points with a phase interval of π / 2 as the four original estimation parameters A, B, C, and D, where A represents the point where the light intensity rises, B represents the point where the light intensity is maximum, C represents the point where the light intensity falls, and D represents the point where the light intensity is minimum. Based on these four original parameters, the current light intensity N, contrast V, and fringe phase φ of the interference fringes are estimated; Calculate the fringe contrast. When the contrast exceeds the threshold, it means that interference fringes appear, and the next step is to calculate the translation error; otherwise, the previous level of dispersion fringe method is used for rough measurement and adjustment; Calculate the translation error: divide the four signals A, B, C, and D into two bands respectively, and invert the translation error using the fringe phase difference between the two bands.

6. The method according to claim 5, characterized in that: The current light intensity N, contrast V and fringe phase φ of the interference fringe are expressed as N=A+B+C+D 7. An optical synthetic aperture coarse and fine two-stage common phase error detection system, characterized in that: It includes a beam splitter group D1, a beam splitter group D2, a spacing adjustment mirror group, a pointing detection system, a dispersion fringe sensing system, a Mach-Zehnder light combining interference system, and a control system; The beam splitter group D1 and the beam splitter group D2 are used to reflect the two sub-beams to the pointing detection system, and the beam passing through the beam splitter group D1 is transmitted to the spacing adjustment mirror group, and the spacing adjustment mirror group adjusts the optical axis spacing of the two sub-beams and then transmits them to the dispersion fringe sensing system; The light beam passing through the beam splitter group D2 is input into the Mach-Zehnder type light combining interferometer system; The pointing detection system is used to calculate the tilt error and send the tilt error to the control system; The dispersion fringe sensing system is used to achieve coarse precision detection of translation error, and send the detected coarse precision translation error to the control system; The Mach-Zehnder light combining interference system is used to form four signals A, B, C, and D with a phase difference interval of π / 2, and detect the translation error through fringes, and send the obtained high-precision translation error to the control system; The control system corrects the error corresponding to the optical synthetic aperture in real time according to the received tilt error, coarse-precision translation error and high-precision translation error.

8. The optical synthetic aperture coarse and fine two-stage common phase error detection system according to claim 7, characterized in that: The Mach-Zehnder light combining interference system comprises four plane reflectors, two wedge-shaped beam splitters I and one wedge-shaped beam splitter II; two parallel light beams are incident on the two wedge-shaped beam splitters I and are split into four light beams, which are respectively reflected by two plane reflectors to the wedge-shaped beam splitter II for a second beam splitting and beam combining, and four light beams are output, each of which is formed by double-aperture light combining, the optical path difference of the two combined light beams on the output side with the same direction as the incident light is zero, and the optical path difference of the two combined light beams on the other side is π, and the piezoelectric displacement stage of the wedge-shaped beam splitter I on the other side is fine-tuned to increase the phase of the reflected light beam by π / 2 at a specified wavelength, so that the optical path differences of the output four light beams are 0, π / 2, π, and 3π / 2, respectively, so that the ABCD four-phase signal acquisition can be realized.

9. The optical synthetic aperture coarse and fine two-stage common phase error detection system according to claim 7, characterized in that: The detecting translation error by fringes comprises: Scan the interference fringes formed by the two-aperture light beams, and select the light intensity of four points with a phase interval of π / 2 as the four original estimation parameters A, B, C, and D, where A represents the point where the light intensity rises, B represents the point where the light intensity is maximum, C represents the point where the light intensity falls, and D represents the point where the light intensity is minimum. Based on these four original parameters, the current light intensity, contrast V, and fringe phase φ of the interference fringes are estimated; Calculate the fringe contrast. When the contrast exceeds the threshold, it means interference fringes appear, and the next step is to calculate the translation error. Otherwise, perform the dispersion fringe method rough measurement and adjustment again. Calculate the translation error: divide the four signals A, B, C, and D into two bands respectively, and invert the translation error using the fringe phase difference between the two bands.

10. The optical synthetic aperture coarse and fine two-stage common phase error detection system according to claim 7, characterized in that: The control system comprises an optical path difference adjustment K mirror and an optical axis adjustment swing mirror installed on both sub-beams; the optical axis adjustment swing mirror is used to adjust and correct the tilt error; and the optical path difference adjustment K mirror is used to correct the translation error.

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