A method and system for stellar light interferometric phase detection based on wideband polarization modulation

Abstract

The present application relates to a starlight interference phase detection method, which is based on wide-band polarization modulation, uses a Fresnel prism, a beam splitter prism and a polarization beam splitter prism to modulate the phase of starlight, and improves the optical path difference detection precision to even higher phase levels; uses a dispersion prism to obtain the channel spectrum of combined starlight for group delay detection, and has a large dynamic detection range and a detection precision of one wavelength order, which provides a guarantee for the effectiveness of phase detection. According to the group delay detection result, the optical path difference is compensated through a delay line system to ensure that the optical path difference change in the phase detection process does not exceed the dynamic range. According to the statistical average of the phase detection results of multiple wavelengths, the detection precision is improved. The phase detection and group delay detection of the present application obtain the required images through the same optical path at the same time, and there is no time domain error. The present application effectively combines the advantages of high precision of phase detection and large dynamic range of group delay detection, and improves the robustness of phase detection in starlight interference.

Description

TECHNICAL FIELD

[0001] The present application relates to a phase detection method; it relates to the technical field of celestial high-resolution imaging, astronomical terminal equipment, optical detection, stellar interferometer, etc., in particular to a stellar interferometer phase detection method based on wide-band polarization modulation, and more particularly to a phase detection method applied to a stellar interferometer device to ensure the matching accuracy of the optical path difference between different sub-apertures. BACKGROUND

[0002] Astronomers have never stopped pursuing high resolution. The angular diameter of most stars is in the order of milliarcsecond, and the international running telescope can only form a point image, and cannot obtain the detailed information of the star surface. Even the resolution of the 39-meter telescope E-ELT under construction has just crossed the milliarcsecond level. High resolution corresponds to a greater demand for the aperture of the telescope. The aperture of the telescope cannot be increased indefinitely, and the cost of building the telescope is proportional to the square of the aperture. The increase of the aperture of the telescope will greatly increase the cost.

[0003] The long baseline stellar interferometer technology is a method of realizing high-resolution measurement or imaging by mutual interference of light from multiple separate telescopes. The resolution can be further improved by increasing the number of telescopes and the length of the baseline. When the length of the baseline is extended to the order of hundreds of meters, the ability of celestial measurement and imaging observation in the order of micro-arcsecond can be obtained. The essence of this method is to precisely measure the contrast of interference fringes. The changes in optical path difference caused by factors such as the rotation of the earth, the projection change of the baseline, and the atmospheric disturbance will affect the measurement accuracy of the contrast. Therefore, precisely determining the optical path difference between starlight from different telescopes and locking it at "0" as much as possible to enable the starlight interference fringes of the scientific terminal to be recorded for a long time is the key to realizing high-precision interferometric measurement.

[0004] Phase detection can measure the order of magnitude of the change in optical path difference. In the design of a stellar interferometer, a delay line and other devices are used to adjust the optical path difference in real time to realize precise measurement of the contrast of the fringes. The phase detection method needs to be adjusted according to the actual detection range and environmental conditions. The common phase detection methods in the field of surface detection cannot be directly applied to the stellar interferometer. SUMMARY

[0005] In order to solve the two technical problems existing in the prior art phase detection technology: 1. It does not meet the real-time detection needs of the stellar interferometer device; 2. The dynamic range of phase detection cannot cover the change interval of the optical path difference between starlight from different sub-apertures. The present application provides a stellar interferometer phase detection method based on wide-band polarization modulation, and the specific scheme is as follows:

[0006] Two beams of starlight pass through a polarization modulation phase detection light path, and the phase difference interval is four-channel spectral images with phase difference interval of

[0007] acquiring channel spectral images, capturing channel spectral images with optical path difference information, locking optical path difference within one wavelength;

[0008] acquiring channel spectral intensity at four images and multiple wavelengths, calculating phase difference, and statistically averaging optical path difference;

[0009] group delay detection simultaneously monitors optical path difference fluctuations.

[0010] Further, the phase difference interval of the four-channel spectral images obtained simultaneously is The specific method of the four-channel spectral images with phase difference interval of is to introduce a phase shift of by a Fresnel prism to modulate one of the starlight beams, and a corresponding compensation prism to compensate the optical path of the other starlight beam.

[0011] The spectroscopic prism introduces a phase shift of and combines the two starlight beams.

[0012] The four-channel spectral images with phase difference interval of

[0013] Further, the specific process of capturing channel spectral images with optical path difference information is:

[0014] First, a coarse group delay detection method is used, i.e., a coarse group delay detection method is used in combination with a delay line system for rapid scanning motion to quickly reduce the optical path difference within the dynamic range of group delay detection.

[0015] Then, a fine group delay detection method is used, i.e., group delay detection optical path difference, delay line system real-time compensation optical path difference, through delay line system locking optical path difference, locking optical path difference within one wavelength; fine group delay detection real-time monitoring optical path difference, when the optical path difference changes beyond one wavelength, immediately respond, the optical path difference is relocked within one wavelength.

[0016] Further, the process of the coarse group delay detection method includes:

[0017] Fast Fourier transform algorithm is used to solve channel spectral spectrum to obtain the number of fringes;

[0018] According to the formation of channel spectral, the functional relationship between the number of channel spectral fringes and the optical path difference between the two starlight beams is established;

[0019] According to the channel spectral spectrum, it is judged whether the channel spectral with optical path difference information is captured;

[0020] According to the functional relationship between the number of channel spectral fringes and the optical path difference, the optical path difference is obtained.

[0021] Furthermore, the process of the refined group delay detection method includes:

[0022] Based on the formation of the channel spectrum, a functional relationship is established between the number of channel spectral fringes and the optical path difference between the two beams of starlight;

[0023] Fill the channel spectral signal with zeros;

[0024] The channel spectral spectrum is solved by the periodogram algorithm to obtain the number of fringes, and the optical path difference is obtained according to the functional relationship between the number of channel spectral fringes and the optical path difference.

[0025] Furthermore, the delay line system consists of two stages, which work together to complete optical path scanning and optical path difference compensation;

[0026] The first stage is a piezoelectric displacement platform used to finely adjust the optical path of starlight, maintaining and locking the optical path difference between starlight beams; the second stage is a high-precision linear displacement platform used to scan optical path capture fringes and to compensate in real time for the inherent optical path difference between starlight beams caused by the Earth's rotation by looking up a table; the first-stage piezoelectric displacement platform is placed on the second stage, and the second-stage delay line is installed before the polarization modulation phase detection optical path, with a delay line system on each branch of starlight beams.

[0027] Furthermore, the group delay detection simultaneously monitors the optical path fluctuation process, including:

[0028] When the optical path difference fluctuation is less than the dynamic range of phase detection, the monitoring state is maintained, and the optical path difference detection result is determined by phase detection. When the optical path difference fluctuation is greater than the dynamic range of phase detection, the optical path difference detection result is determined by group delay detection, which takes over the delay line control and relocks the optical path difference to within the dynamic range of phase detection for phase detection. When the optical path difference fluctuation is greater than the dynamic range of group delay detection, the optical path difference detection fails, and the optical path is rescanned through the delay line system to restore the optical path difference detection.

[0029] The present invention also provides a wide-band polarization-modulated stellar light interferometric phase detection system based on the above method, comprising: a polarization-modulated phase detection optical path forming system and a detection and tracking system;

[0030] The polarization modulation phase detection optical path forming system includes: a phase-shifting optical path, an extraction optical path, and a dispersion optical path.

[0031] The detection and tracking system includes: a delay line, a camera, and a control device.

[0032] In this invention, wideband group delay detection is used in parallel to ensure that the optical path difference remains within the dynamic range of phase detection (within one wavelength). The phase difference is calculated in real time from multiple interferometric images and fed back to the delay line system for closed-loop phase tracking. Phase detection is performed after the optical path difference is locked within the dynamic detection range, and four phase difference intervals are obtained simultaneously by modulating the phase using multiple polarization optical devices. The phase detection is performed using multiple interferometric images. The wideband group delay detection disperses the combined light into channel spectra using dispersive elements such as prisms, providing a large dynamic detection range and detection accuracy superior to the phase detection wavelength. The group delay detection result is fed back to the delay line system to compensate the optical path difference in real time to within the dynamic range of phase detection, thus satisfying the phase detection conditions. The multiple interferometric images used for phase detection and the channel spectrum images used for group delay detection are simultaneously acquired from one or more cameras to ensure temporal consistency between the two detection stages.

[0033] The group delay detection and phase detection are achieved through Figure 1 The same optical path is used to acquire images and complete calculations; the detection process follows... Figure 2 The collaborative logic of this method is characterized by its two-stage detection, ensuring that the optical path difference during phase detection remains within a dynamic range and avoiding errors. The image is blurry, causing the detection to fail.

[0034] In other words, this invention includes group delay detection, phase detection, and a cooperative method; group delay detection has a large dynamic detection range, and its detection accuracy is sufficient to allow the delay line system to lock the optical path difference within the dynamic range of phase detection; phase detection has a smaller dynamic detection range, typically within one wavelength, and its accuracy can reach [missing information]. Even higher, providing phase compensation and differential delay optical path difference calculation for delay lines; the cooperative method enables the above two detection methods to be implemented in the same optical path, and coordinates group delay detection to complete real-time phase detection.

[0035] Group delay detection: There are two modes: fine group delay detection and coarse group delay detection. After the two beams of starlight are combined, the channel spectrum is obtained by dispersion through a prism or grating. The optical path difference is obtained by analyzing the spectrum of the channel spectrum and fed back to the delay line system for real-time optical path difference compensation, stabilizing the optical path difference within the dynamic range of phase detection technology (within one wavelength).

[0036] Phase detection: Phase difference between two beams Starlight within a certain wavelength, after passing through a Fresnel prism, a compensating prism, a beam splitter, and a polarizing beam splitter, yields four sets of phase differences, respectively. , , as well as The combined beam is used to obtain the original phase difference through a four-step phase-shifting algorithm. .

[0037] Furthermore, the four sets of phase difference intervals are obtained. The process of beam combining includes:

[0038] Two beams of light are combined into two beams of light by beam splitter 3, and then separated into two beams of light with perpendicular vibration directions by polarizing beam splitter 8 and polarizing beam splitter 9, resulting in four beams of light.

[0039] The light beam is refracted between the main optical elements by a plane mirror, and the refracting angle of the beam is less than 90° to ensure that the polarization state of the beam does not change.

[0040] Furthermore, the four beams are combined at the pupil plane, with the beam direction aligned with the optical axis. After passing through a prism, the beams are expanded in the wavelength dimension to obtain four phase-shifted channel spectra, thus obtaining phase-shifted interference images at multiple wavelengths.

[0041] Collaborative technique: Four beams of light pass through a dispersive prism to obtain channel spectra, simultaneously producing four channel spectral images. This results in phase-shifted interferometry images at multiple wavelengths, ensuring temporal consistency between group delay detection and phase detection. Both detection methods follow... Figure 2 The collaborative logic enables real-time monitoring of optical path difference during phase detection, while group delay detection is performed to ensure the reliability of phase detection.

[0042] Furthermore, since the optical path change caused by phase shift is relatively small in the four channel spectral images, one channel spectral image is selected as the reference when performing group delay detection. The group delay optical path difference is then ensured to be within the dynamic range of phase detection by combining the delay line system.

[0043] The present invention has the following beneficial effects:

[0044] (1) It takes into account both the high precision of phase detection and the large dynamic range of group delay detection. The dynamic range of traditional phase detection methods is less than one wavelength, which is far from meeting the optical path difference detection requirements of long baseline optical interference. By using group delay detection technology as a buffer, the system can ensure that phase-level optical path difference detection is effective while greatly expanding the dynamic detection range of the system.

[0045] (2) Phase-shifting interferometric images and channel spectral images are acquired simultaneously, eliminating temporal errors. By combining the polarization phase-shifting optical path with the channel spectral detection optical path, phase detection and group delay detection can be performed using the same set of images, avoiding temporal inconsistencies. Meanwhile, traditional phase-shifting detection methods require additional moving optical elements to modulate the phase in the temporal domain, resulting in inconsistent acquisition times for the four phase-shifting interferometric images. This introduces temporal detection errors and the time required for phase shifting, leading to low efficiency and introducing motion errors from the elements. By using multiple polarization optical devices to modulate the phase in the spatial domain, four phase-shifting interferometric images can be acquired simultaneously by the camera, avoiding temporal errors and improving detection efficiency. Attached Figure Description

[0046] Figure 1 A schematic diagram of the polarization modulation phase detection optical path according to the present invention is shown.

[0047] Figure 2 A schematic diagram of the collaborative detection logic according to the present invention is shown.

[0048] Figure 3 Show Schematic diagram of the internal structure and optical path of a Fresnel prism

[0049] Figure 4 This diagram illustrates a simulation of the intensity and phase detection results of four phase-shifted interferograms at different wavelengths when detecting a 400 nm optical path difference using a phase detection method based on polarization modulation.

[0050] Figure 5 The simulation results and error diagram of optical path difference detection are shown when the phase shift error is 5%. Detailed Implementation

[0051] The embodiments of the present invention are given below with reference to the accompanying drawings to illustrate the technical solution in detail.

[0052] A stellar light interferometric phase detection method based on wideband polarization modulation. Figure 1 This is a schematic diagram of the optical path used in this invention, which includes the key components for implementing the detection method in this invention and is the basis for realizing real-time phase detection.

[0053] Example 1

[0054] This embodiment specifically illustrates the system structure (optical path) of applying the present invention.

[0055] like Figure 1 As shown, the present invention is a stellar light interferometric phase detection system based on wideband polarization modulation, comprising: a polarization modulation phase detection optical path forming system and a detection and tracking system.

[0056] The polarization modulation phase detection optical path forming system includes three parts: a phase-shifting optical path, an extraction optical path, and a dispersive optical path. The telescopes at both ends of the baseline simultaneously observe the same target to obtain starlight A and starlight B.

[0057] The phase-shifting optical path includes Fresnel prism 1, compensating prism 2, beam splitter prism 3, and reflecting mirrors 4, 5, 6, and 7. Starlight A passes through these mirrors in sequence. Fresnel prism 1 and reflector 4, starlight B passes through compensating prism 2 and reflector 5 in sequence. After the two beams pass through beam splitter prism, the reflected light of starlight A and the transmitted light of starlight B are combined into beam C, and the transmitted light of starlight A and the reflected light of starlight B are combined into beam D.

[0058] The Fresnel prism 1 Figure 3 As shown, it includes three reflecting surfaces at specific angles, so that the incident light undergoes three reflections to achieve a balance between the P and S components of the beam. Phase shifting, while ensuring that the outgoing light and the incident light are coaxial;

[0059] The compensation prism 2 is made of the same material as the Fresnel prism and is used to compensate for the distance between starlight A and starlight B. Optical path deviation caused by internal reflection of Fresnel prism 1;

[0060] The beam splitter 3 ensures that starlight A and starlight B are combined into beams C and D, while simultaneously introducing a beam between the transmitted and reflected light of the P component of the beam. Phase shift;

[0061] The extraction optical path includes polarizing beam splitters 8 and 9. Beams C and D pass through polarizing beam splitters 8 and 9 respectively and are split into two beams with mutually perpendicular polarization states.

[0062] The dispersive optical path includes dispersive prisms 10, 11, 12, and 13. The four beams of light extracted by the extraction optical path pass through the four dispersive prisms respectively to obtain four channel spectra that have been polarized and modulated.

[0063] The detection and tracking system includes: a delay line, a camera, and a control device.

[0064] Each beam of starlight will be equipped with an independent delay line system. The delay lines are placed before the detection optical path. Before passing through Fresnel prism 1 and compensation prism 2 respectively, starlight A and starlight B first pass through a knife-edge prism, entering delay lines A and B perpendicular to the starlight, respectively. Then, they are reflected by another reflective surface of the knife-edge prism and enter the detection optical path. (When the beam aperture is small, a knife-edge prism can be used, utilizing both of its reflective surfaces as deflection surfaces for entering and exiting the delay line system. When the beam aperture is large, an independent plane mirror is required to deflect the optical path. In this embodiment, a knife-edge prism is used as an example of the delay line system.)

[0065] The camera is used for imaging; four cameras can be set up and placed in four dispersive optical paths respectively; alternatively, four images can be focused onto one camera using reflectors or optical fibers to ensure that four images are obtained simultaneously; this embodiment is an example. Figure 1 The image shows four cameras positioned behind the imaging lens in the dispersive optical path.

[0066] The control device is used to acquire channel spectral images, calculate optical path difference and phase difference, and track fringes; it employs a parallel structure for computation, and a message queue ensures parallel timing. The control device is connected to the camera.

[0067] Example 2

[0068] This embodiment specifically illustrates the method for phase detection based on polarization modulation according to the present invention.

[0069] pass Figure 1 Phase detection can be achieved by implementing a phase-shifting optical path in the optical path, using wavelength. For example, take [location].

[0070] Assuming the phases of starlight A and starlight B are respectively and Phase difference And their respective P components are in phase with their S components;

[0071] Starlight A passes An additional Fresnel prism is applied between the P and S components. Phase delay;

[0072] The S and P components in starlight B do not experience phase delay after passing through the compensation prism.

[0073] At point 3 of the beam splitter, starlight A and starlight B are combined to form beams C and D, simultaneously causing... Phase delay;

[0074] The beam C includes reflected light from starlight A and transmitted light from starlight B;

[0075] The beam D includes the transmitted light from starlight A and the reflected light from starlight B;

[0076] Beams C and D pass through polarizing beam splitters 8 and 9, respectively, separating the S and P components of the beams and extracting four beam combinations. The phase differences of the four beam combinations are as follows:

[0077] In the four-channel spectral images, at wavelength The light intensity function at a certain point can be expressed as:

[0078]

[0079] in, wavelength Normalized spectral intensity at that location wavelength The stripe contrast at that location, s Group delay optical path difference, wavelength The phase difference at that point. When the delay line system controls the optical path difference within one wavelength through group delay detection, the group delay optical path difference... The phase difference at the current wavelength It can be represented as:

[0080]

[0081] The detection accuracy of optical path difference can be further improved by converting the phase difference at different wavelengths into optical path difference and then statistically averaging the results.

[0082]

[0083] Phase detection has thus been achieved based on polarization modulation. Equation (4) represents the optical path difference, where... n It is the total number of wavelengths included in the statistical average. i It is the wavelength number. i =1,2,3,…, n First, the phase difference at multiple wavelengths is obtained and then converted into optical path difference. The average value is then used as the actual optical path difference, which is equivalent to taking the average value of multiple measurements, thus improving the accuracy statistically.

[0084] Example 3

[0085] This embodiment illustrates the implementation of a stellar light interferometric phase detection method based on wideband polarization modulation through numerical simulation.

[0086] With a detection wavelength of 600-900 nm, a detection pixel count of 300, and a zero-fill factor of 5 (i.e., a spectral subdivision factor of 5), the coarse group delay detection accuracy is 1800 nm, the fine group delay detection accuracy is 360 nm, and the theoretical dynamic range of group delay detection is 270 μm (in reality, this value will be slightly smaller due to aberrations and other factors). This optical path difference detection accuracy ensures that the group delay optical path difference is 0, enabling phase detection.

[0087] The phase difference was calculated by numerical simulation according to formulas (1), (2), and (3). Four phase-shifted interferograms were obtained at wavelengths of 600-900 nm (1 nm interval) according to formulas (1) and (2), respectively. Then, the phase was calculated using a four-step phase-shifting algorithm according to formula (3). When the optical path difference was 400 nm, the intensity of the four phase-shifted interferograms and the phase detection results at different wavelengths are as follows: Figure 4 As shown.

[0088] Considering the need to reserve a certain range for delay line compensation accuracy, according to formula (4), the phase is converted into optical path difference in the wavelength range of 750-900nm and the optical path difference is statistically averaged to obtain an optical path difference detection result of 400nm, which verifies the feasibility of the phase detection method.

[0089] This method is error-free under ideal conditions. Ignoring environmental factors, its main error source is phase shifting error. Based on the inherent precision of existing phase-shifting devices, if the overall phase shifting error of the four-step phase shifting is 5%, and the optical path difference is detected in the 100-500nm range, the simulation results and errors are as follows: Figure 5 As shown.

[0090] Simulation results show that the average error in detecting the optical path difference is 23.6 nm, and the detection accuracy is better than that of other methods. In reality, considering the influence of factors such as mechanical vibration, environmental conditions, and airflow disturbances, the detection accuracy will be lower than this value.

[0091] Example 4

[0092] This embodiment combines Figure 2 A detailed explanation of the implementation process of combining group delay detection and phase detection in stellar optical interferometry:

[0093] First, by combining coarse group delay detection with rapid scanning motion of the delay line, the optical path difference is quickly reduced to within the dynamic range of group delay detection;

[0094] Switch the group delay detection method to fine mode and use the delay line system to finely compensate for the optical path difference, locking it within the dynamic range of phase detection;

[0095] Phase detection is enabled, and a four-step phase-shifting algorithm is used to solve four interference images in real time to obtain phase information at each wavelength. Real-time phase compensation is then performed using a delay line system according to actual scientific needs.

[0096] While performing phase detection, fine group delay detection monitors the optical path difference in real time. When the optical path difference changes beyond one wavelength, it responds promptly by pausing phase detection and taking over the delay line feedback to relock the optical path difference within one wavelength.

[0097] When a large-scale abrupt change in optical path difference causes group delay detection to fail, the exposure of interference fringes on the scientific terminal is immediately stopped. The optical path difference is then reduced again through coarse group delay detection and rapid scanning motion of the delay lines, and the system re-enters fine group delay detection mode and phase detection.

Claims

1. A method for phase detection of stellar light interferometry based on wideband polarization modulation, characterized in that... include: Two beams of starlight are passed through a polarization-modulated phase detection optical path, and the phase difference interval is obtained simultaneously. Four-channel spectral images; The phase difference interval obtained simultaneously is The specific method for obtaining the four-channel spectral images is as follows: one beam of starlight is modulated using a Fresnel prism, and then introduced... Phase shift occurs, and the corresponding compensating prism compensates for the optical path of another beam of starlight. Introduced by a beam splitter Phase shift and combine the two beams of starlight; The phase difference interval is extracted using a polarizing beam splitter. Four-channel spectral images; Acquire channel spectral images, capture channel spectral images with optical path difference information, and lock the optical path difference to within one wavelength; The optical path difference was obtained by acquiring the spectral intensity of the four images at multiple wavelengths, calculating the phase difference, and statistically averaging them. Group delay detection simultaneously monitors optical path difference fluctuations.

2. The stellar light interferometric phase detection method based on wideband polarization modulation according to claim 1, characterized in that, The specific process of capturing the channel spectral image with optical path difference information is as follows: First, a coarse group delay detection method is used, which is combined with a delay line system to quickly scan and move, thereby rapidly reducing the optical path difference to within the dynamic range of group delay detection. Then, a fine group delay detection method is adopted, namely, group delay detection of optical path difference. The delay line system compensates for the optical path difference in real time and locks the optical path difference within one wavelength through the delay line system. Fine group delay detection monitors the optical path difference in real time. When the optical path difference changes beyond one wavelength, it responds immediately and locks the optical path difference back within one wavelength.

3. The stellar light interferometric phase detection method based on wideband polarization modulation according to claim 2, characterized in that, The coarse group delay detection method includes the following steps: The Fast Fourier Transform algorithm is used to solve the channel spectral spectrum and obtain the number of fringes; Based on the formation of the channel spectrum, a functional relationship is established between the number of channel spectral fringes and the optical path difference between the two beams of starlight. Determine whether to capture the channel spectrum containing optical path difference information based on the channel spectral spectrum. The optical path difference is obtained from the functional relationship between the number of spectral fringes in the channel and the optical path difference.

4. The stellar light interferometric phase detection method based on wideband polarization modulation according to claim 2, characterized in that, The process of the fine-grained group delay detection method includes: Based on the formation of the channel spectrum, a functional relationship is established between the number of channel spectral fringes and the optical path difference between the two beams of starlight. Fill the channel spectral signal with zeros; The channel spectral spectrum is solved by the periodogram algorithm to obtain the number of fringes, and the optical path difference is obtained according to the functional relationship between the number of channel spectral fringes and the optical path difference.

5. The stellar light interferometric phase detection method based on wideband polarization modulation according to claim 2, characterized in that, The delay line system consists of two stages, which work together to complete optical path scanning and optical path difference compensation. The first stage is a piezoelectric displacement platform, which is used to finely adjust the optical path of starlight and maintain and lock the optical path difference between starlight. The second stage is a high-precision linear displacement platform used to scan optical path capture fringes and to compensate in real time for the inherent optical path difference between starlight caused by the Earth's rotation by looking up a table; the first-stage piezoelectric displacement platform is placed on the second stage, and the second-stage delay line is installed before the polarization modulation phase detection optical path, with a delay line system on each branch of starlight.

6. The stellar light interferometric phase detection method based on wideband polarization modulation according to claim 1, characterized in that, In the four-channel spectral images, at wavelength The light intensity function at a certain point can be expressed as: ， in, wavelength Normalized spectral intensity at that location wavelength The fringe contrast at that point, where s is the group delay optical path difference. wavelength The phase value at the point; when the delay line system controls the optical path difference within one wavelength using a fine group delay detection method, the group delay optical path difference... Then the wavelength Phase information at the location It can be represented as: ， The accuracy of optical path difference detection can be further improved by statistically averaging the phase information at different wavelengths. ， Formula (4) represents the optical path difference, where n is the total number of wavelengths participating in the statistical average, and i is the wavelength number, i=1,2,3,…,n.

7. The stellar light interferometric phase detection method based on wideband polarization modulation according to claim 1, characterized in that, The group delay detection simultaneously monitors the optical path fluctuation process, including: When the optical path difference fluctuation is less than the dynamic range of phase detection, the monitoring state is maintained, and the optical path difference detection result is determined by phase detection. When the optical path difference fluctuation exceeds the dynamic range of phase detection, the optical path difference detection result is determined by the group delay detection, which then takes over the delay line control and relocks the optical path difference to within the dynamic range of phase detection before performing phase detection. When the optical path difference fluctuation exceeds the dynamic range of the group delay detection, the optical path difference detection fails, and the optical path is re-scanned through the delay line system to restore the optical path difference detection.

8. A stellar light interferometric phase detection system based on wideband polarization modulation, according to the method described in any one of claims 1 to 7, characterized in that, include: Polarization modulation phase detection optical path forming system and detection tracking system; The polarization modulation phase detection optical path forming system includes: a phase-shifting optical path, an extraction optical path, and a dispersion optical path. The phase-shifting optical path includes Fresnel prism (1), compensating prism (2), beam splitter prism (3), and reflector a (4), reflector b (5), reflector c (6), and reflector d (7); starlight A passes through in sequence After passing through the Fresnel prism (1) and the reflector a (4), the starlight B passes through the compensation prism (2) and the reflector b (5) in sequence. After passing through the beam splitter prism (3), the reflected light of starlight A and the transmitted light of starlight B are combined to form beam C, and the transmitted light of starlight A and the reflected light of starlight B are combined to form beam D. The compensating prism (2) is made of the same material as the Fresnel prism and is used to compensate for the distance between starlight A and starlight B. Optical path deviation caused by internal reflection of Fresnel prism (1); The beam splitter (3) ensures that starlight A and starlight B are combined into beams C and D, while simultaneously introducing a beam between the transmitted and reflected light of the P component of the beam. Phase shift; The extraction optical path includes a polarizing beam splitter a (8) and a polarizing beam splitter b (9). The beams C and D pass through the polarizing beam splitter a (8) and the polarizing beam splitter b (9) respectively, and are split into two beams with mutually perpendicular polarization states. The dispersive optical path includes dispersive prism a (10), dispersive prism b (11), dispersive prism c (12) and dispersive prism d (13). The four beams of light extracted by the extraction optical path pass through the four dispersive prisms respectively to obtain four channel spectral images with polarization modulation. The detection and tracking system includes: a delay line, a camera, and a control device. Each beam of starlight is equipped with an independent delay line system, the delay line being placed before the detection optical path. Starlight A and starlight B pass through... Before the Fresnel prism (1) and the compensation prism (2), the light enters the delay line A and delay line B perpendicular to the starlight through the knife-edge prism, and then is reflected by the other reflective surface of the knife-edge prism into the detection light path. The camera is used for imaging; four cameras are placed behind the imaging lens of the dispersive optical path; The control device is used to acquire channel spectral images, calculate optical path difference and phase difference, and track fringes; it employs a parallel structure to perform the operations and ensures parallel timing through a message queue; the control device is connected to the camera.

9. A stellar light interferometric phase detection system based on wideband polarization modulation according to claim 8, characterized in that: The four polarization-modulated channel spectral images are obtained simultaneously in the optical path and used for both group delay detection and phase detection.

Images