Wide-spectrum interference type star sensor based on eight-optical-wedge light splitting assembly and centroid positioning method of wide-spectrum interference type star sensor

Abstract

The invention discloses a wide-spectrum interference type star sensor based on an eight-optical-wedge light splitting assembly and a centroid positioning method of the wide-spectrum interference type star sensor, and belongs to the technical field of spacecraft attitude measurement. In order to solve the problem that the single-star measurement precision of an interference type star sensor is reduced, the interference type star sensor comprises an interference assembly, an eight-optical-wedge light splitting assembly, a focusing assembly and a detector which are arranged in sequence, the interference assembly comprises two gratings G1 and G2 which are spaced by a certain distance and is used for modulating the starlight phase and further generating interference fringes; the eight-optical-wedge light splitting assembly is an optical wedge array composed of eight optical wedges and is used for dividing interference fringes into eight parts of fringe light. The focusing assembly is used for focusing and imaging the stripe light at different positions of the detector; the detector is located on the focal plane of the focusing assembly and used for receiving the starlight image. By adopting an eight-optical-wedge light splitting structure, the single-satellite measurement precision of the system in a wide-spectrum working environment is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of spacecraft attitude measurement, and in particular relates to a wide-spectrum interferometric star sensor based on an eight-optical wedge spectrometer and a centroid positioning method thereof. Background Art

[0002] Star sensors are instruments that acquire starry sky images and output their attitude in an inertial coordinate system. They offer advantages such as high precision, all-day autonomous navigation, and zero cumulative error. They are currently widely used on platforms such as satellites, missiles, and ships. With the continuous escalation of missions, the requirements for attitude measurement accuracy from star sensors are becoming increasingly stringent. Due to constraints such as payload mass and power consumption, further improvements in the attitude measurement accuracy of traditional star sensors have become difficult. Improving the accuracy of single-star measurements while maintaining the star sensor's observation range has become a research hotspot in recent years.

[0003] Computational interferometry methods offer a new approach to surpassing the precision limits of single-star measurements using traditional star sensors. Interferometric star sensors incorporate an interferometer component at the front end of traditional star sensors to modulate the starlight phase, coupling the incident angle information to the energy distribution of the image points. This allows for highly accurate calculation of the starlight incident angle based on the energy relationship between the image points. The interferometric star sensor's effective utilization of starlight phase information enables single-star measurement accuracy to reach orders of magnitude higher than that of traditional star sensors using the same field of view.

[0004] Based on the principle of computational interferometry, the Changchun Institute of Optics, Fine Mechanics and Physics has proposed an interferometric star sensor based on a diffraction grating. The device consists of two Ronchi gratings, four optical wedges, an imaging lens, and a planar array detector. Theoretical analysis shows that this structure can significantly improve the accuracy of single-star measurements. However, this design has the following technical limitations: the system only utilizes the ±1st-order diffraction light from the grating. Although the Ronchi grating can effectively suppress non-zero even-order diffraction, it is insufficient to suppress the zeroth-order diffraction under conditions of incident starlight over a wide spectrum. This critical design flaw will result in a significant decrease in single-star measurement accuracy due to the zeroth-order diffraction effect when the system operates over a wide spectrum, ultimately restricting the actual performance of the star sensor. Summary of the Invention

[0005] The problem to be solved by the present invention is to improve the problem that the single-star measurement accuracy of an interferometric star sensor decreases due to grating zero-order diffraction under wide-spectrum incidence conditions, and propose a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer component and a method for locating the center of mass thereof.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A wide-spectrum interferometric star sensor based on an eight-wedge spectrometer assembly comprises an interferometer assembly, an eight-wedge spectrometer assembly, a focusing assembly, and a detector arranged in sequence;

[0008] The interference component is two gratings G1 and G2 separated by a certain distance, which are used to modulate the phase of starlight and thus generate interference fringes;

[0009] The eight-wedge splitter assembly is a wedge array composed of eight wedges, which is used to split the interference fringes into eight parts of fringed light;

[0010] The focusing component is used to focus the stripe light and form an image at different positions of the detector;

[0011] The detector is located at the focal plane of the focusing assembly and is used to receive the image of starlight.

[0012] Furthermore, the spacing between the gratings G1 and G2 in the interference assembly is z t , the grating period of G1 and G2 is the same, the grating period is p, the z-axis is the optical axis of the optical system, the directions of the lines of the two gratings are perpendicular to the optical axis, and the angle between the directions of the lines of the two gratings and the y-axis is ɛ, satisfying , where b is the width of a single wedge and the ruling direction is symmetric about the y-axis.

[0013] Furthermore, the eight wedges of the eight-wedge spectrometer are arranged along the y-axis to deflect the eight portions of starlight in different directions. The dimensions of each of the eight wedges are a×b, satisfying a=8b, where a and b represent the length of the wedge along the x-direction and the length of the wedge along the y-direction, respectively. The rear surface of the eight-wedge spectrometer is configured as the entrance pupil of the broadband interferometric star sensor based on the eight-wedge spectrometer.

[0014] A centroid positioning method for a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer assembly is provided, which is implemented based on the wide-spectrum interferometric star sensor based on an eight-wedge spectrometer assembly and includes the following steps:

[0015] S1. Construct a model for the relationship between the incident angle of starlight and the image point energy of a broadband interferometric star sensor based on an eight-wedge spectrometer.

[0016] S2. Based on the energy distribution of the image points obtained by the detector, the coordinates of the image points on the image plane are extracted using the grayscale weighting method, and the grayscale of each image point is calculated;

[0017] S3 step S2 obtained by the grayscale image point, determine the largest grayscale image point, extract the maximum grayscale image point centroid coordinates;

[0018] S4. Based on the centroid coordinates of the image point with the maximum grayscale obtained in step S4, apply the principles of geometric optics imaging to estimate the starlight incident angle and the starlight phase integer ambiguity;

[0019] S5. Based on the image point grayscale obtained in step S2, the main value of the starlight phase is calculated, and the main value of the phase is added to the phase integer ambiguity obtained in step S4 to obtain a high-precision starlight phase;

[0020] S6. Calculate the high-precision starlight incident angle based on the high-precision starlight phase obtained in step S5 to obtain the high-precision image point centroid coordinates.

[0021] Furthermore, the specific implementation method of step S1 includes the following steps:

[0022] S1.1. Calculation of the angular spectrum of starlight after passing through interferometers and spectrometers based on angular spectrum propagation theory , the calculation formula is:

[0023]

[0024] in, represents the Fourier transform operation; represents the complex amplitude of starlight at the front end of the star sensor; represents the complex amplitude transmittance of grating G1; is the transfer function of starlight from the rear surface of G1 to G2; represents the complex amplitude transmittance of grating G2; represents the complex amplitude transmittance of the eight-wedge spectrometer; Represents the convolution operation;

[0025] The calculation formula of the complex amplitude of starlight at the front end of the star sensor is:

[0026]

[0027] in, represents the amplitude of starlight; j represents the imaginary unit; λ represents the wavelength of starlight; α and β represent the complementary angles between the starlight and the x-axis and y-axis of the star sensor, respectively; x and y represent the coordinates of the starlight at the front end of the star sensor, respectively;

[0028] The calculation formula of the complex amplitude transmittance of gratings G1 and G2 is:

[0029]

[0030]

[0031] in, is the m-th order diffraction coefficient of grating G1 at wavelength λ; is the first wavelength of grating G2 at wavelength λ Order diffraction coefficient;

[0032] The transfer function of starlight from the rear surface of G1 to G2 is expressed as:

[0033]

[0034] Among them, f x represents the spatial frequency of starlight in the x direction, f y represents the spatial frequency of starlight in the y direction;

[0035] The expression of the complex amplitude transmittance of the eight-wedge spectrometer is:

[0036]

[0037] in, 、 They represent the deflection angles of starlight in the x-direction and y-direction after passing through the nth light wedge; rect represents the rectangular function, and the relationship between a and b is as follows: As shown:

[0038]

[0039] The relationship between the wedge angles is as follows: As shown:

[0040] ;

[0041] S1.2. Combine the formula in step S1.1 to obtain The expansion formula is as follows:

[0042]

[0043] S1.3. Design an analysis of the zero-order diffraction image produced by starlight passing through an interferometric star sensor. Based on Parseval's theorem, the energy of the zero-order image produced by starlight passing through the interferometer, the nth optical wedge, and the focusing element is:

[0044]

[0045] in, is the stellar spectrum range;

[0046] The x- and y-positions of the zero-order image point produced by starlight after it passes through the interferometer, the nth optical wedge, and the focusing assembly are:

[0047]

[0048] Where f represents the focal length of the focusing component;

[0049] S1.4. To facilitate the analysis of zero-order image energy, construct an intermediate variable 、 、 , respectively:

[0050]

[0051]

[0052]

[0053] in, When m is 1 The value of When m is -1 The value of

[0054] Then we have:

[0055]

[0056] At this time, even if the zero-order diffraction of the grating is not 0, Equation (16) is strictly valid, and the expression is:

[0057]

[0058] According to the principle of geometric optics imaging:

[0059]

[0060] At this time, the image point passing through the nth optical wedge coincides with the image point passing through the (n+4)th optical wedge, completing the establishment of the relationship between the incident angle of starlight and the image point energy.

[0061] Furthermore, the specific implementation method of step S2 includes the following steps:

[0062] S2.1. First, estimate the background noise threshold using the following formula:

[0063]

[0064] Among them, μ is the grayscale mean of the background, σ is the grayscale standard deviation of the background;

[0065] Perform threshold segmentation on the star map;

[0066] S2.2. Partitioning connected domains of image points based on scanning methods.

[0067] S2.3. Extract the centroids of the image points based on the grayscale weighting method. The centroid coordinates of the four image points are (x1, y1), (x2, y2), (x3, y3), and (x4, y4), and the grayscales of the four image points are g1, g2, g3, and g4, respectively.

[0068] Furthermore, the specific implementation method of step S3 is to sort the grayscale of the four pixels extracted in step S2 and find the pixel with the largest grayscale. The centroid coordinates of the pixel are marked as (x max ,y max ).

[0069] Furthermore, the specific implementation method of step S4 is to convert the (x max ,y max ) Bring-in , estimate the starlight incident angle 、 , as shown in the formula As shown:

[0070]

[0071] in, 、 They represent the estimated values ​​of the complementary angles between the starlight and the x-axis and y-axis of the star sensor respectively;

[0072] Substitute the estimated starlight incident angle into the formula With style In the equation, we get a rough phase value , and the phase integer ambiguity Make an estimate, the specific calculation method is as follows As shown:

[0073]

[0074] Here, round means rounding to the nearest integer.

[0075] Furthermore, the specific implementation method of step S5 is to substitute the grayscale of the four pixels extracted in step S2 into the formula , that is, 、 、 、 , solve the principal value of the starlight phase , add the starlight phase integer ambiguity and the phase main value to obtain the final starlight phase .

[0076] Furthermore, the specific implementation method of step S6 is a combined and , solve the high-precision starlight incident angle α, as shown in Eq. As shown,

[0077]

[0078] Then, based on the principle of geometric imaging, high-precision coordinates of the image point centroid are obtained.

[0079] Beneficial effects of the present invention:

[0080] The wide-spectrum interferometric star sensor based on the eight-wedge spectrometer assembly described in the present invention suppresses the influence of the grating zero-order diffraction on the starlight measurement accuracy by adopting the eight-wedge spectrometer structure, significantly improving the system's single-star measurement accuracy in a wide-spectrum working environment. This achievement will lay an important theoretical foundation for the system design, performance evaluation and engineering application of the next generation of high-precision star sensors, and further provide reliable technical support for key links such as precise landing and orbit maintenance in deep space exploration missions, ultimately effectively improving the level of my country's astronomical navigation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 This is a schematic structural diagram of a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer assembly according to the present invention;

[0082] Figure 2 Schematic diagram of the arrangement of the two gratings in the optical system according to the present invention;

[0083] Figure 3 Schematic diagram of the three-dimensional structure of the light splitting component of the present invention and its thickness distribution along the optical axis;

[0084] Figure 4 The present invention provides a flow chart of a method for locating the centroid of a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer assembly. DETAILED DESCRIPTION

[0085] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the present invention. That is, the specific embodiments described herein are only some embodiments of the present invention, not all embodiments. Generally, the components of the specific embodiments of the present invention described and illustrated in the drawings herein can be arranged and designed in various different configurations, and the present invention can also have other embodiments.

[0086] Therefore, the following detailed description of the specific embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected specific embodiments of the present invention. All other specific embodiments obtained by those skilled in the art based on the specific embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0087] In order to further understand the content, features and effects of the present invention, the following specific embodiments are given as examples, and the attached Figure 1 -Attached Figure 4 The detailed instructions are as follows:

[0088] Example 1:

[0089] A wide-spectrum interferometric star sensor based on an eight-wedge spectrometer assembly comprises an interferometer assembly, an eight-wedge spectrometer assembly, a focusing assembly, and a detector arranged in sequence;

[0090] The interference component is two gratings G1 and G2 separated by a certain distance, which are used to modulate the phase of starlight and thus generate interference fringes;

[0091] The eight-wedge splitter assembly is a wedge array composed of eight wedges, which is used to split the interference fringes into eight parts of fringed light;

[0092] The focusing component is used to focus the stripe light and form an image at different positions of the detector;

[0093] The detector is located at the focal plane of the focusing assembly and is used to receive the image of starlight.

[0094] Furthermore, the spacing between the gratings G1 and G2 in the interference assembly is z t , the grating period of G1 and G2 is the same, the grating period is p, the z-axis is the optical axis of the optical system, the directions of the lines of the two gratings are perpendicular to the optical axis, and the angle between the directions of the lines of the two gratings and the y-axis is ɛ, satisfying , where b is the width of a single wedge and the ruling direction is symmetric about the y-axis.

[0095] Furthermore, the eight wedges of the eight-wedge spectrometer are arranged along the y-axis to deflect the eight portions of starlight in different directions. The dimensions of each of the eight wedges are a×b, satisfying a=8b, where a and b represent the length of the wedge along the x-direction and the length of the wedge along the y-direction, respectively. The rear surface of the eight-wedge spectrometer is configured as the entrance pupil of the broadband interferometric star sensor based on the eight-wedge spectrometer.

[0096] Furthermore, the focusing component is used to focus and image each portion of the stripes at different positions on the detector.

[0097] Furthermore, the period of the grating G1 and the grating G2 can be selected to be 50 μm, the grating pitch can be selected to be 50 mm, and the grating angle ɛ can be selected to be 0.0149°; and the grating G1 and the grating G2 are Ronchi gratings.

[0098] Furthermore, the light splitting component may be 8 optical wedges arranged along the y-axis, and the size of each optical wedge may be 48 mm × 12 mm;

[0099] Furthermore, the focusing lens group requires no vignetting over the entire field of view.

[0100] Example 2:

[0101] A centroid positioning method for a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer assembly is implemented based on the wide-spectrum interferometric star sensor based on an eight-wedge spectrometer assembly described in Example 1, and includes the following steps:

[0102] S1. Construct a model for the relationship between the incident angle of starlight and the image point energy of a broadband interferometric star sensor based on an eight-wedge spectrometer.

[0103] Furthermore, the specific implementation method of step S1 includes the following steps:

[0104] S1.1. Calculation of the angular spectrum of starlight after passing through interferometers and spectrometers based on angular spectrum propagation theory , the calculation formula is:

[0105]

[0106] in, represents the Fourier transform operation; represents the complex amplitude of starlight at the front end of the star sensor; represents the complex amplitude transmittance of grating G1; is the transfer function of starlight from the rear surface of G1 to G2; represents the complex amplitude transmittance of grating G2; represents the complex amplitude transmittance of the eight-wedge spectrometer; Represents the convolution operation;

[0107] The calculation formula of the complex amplitude of starlight at the front end of the star sensor is:

[0108]

[0109] in, represents the amplitude of starlight; j represents the imaginary unit; λ represents the wavelength of starlight; α and β represent the complementary angles between the starlight and the x-axis and y-axis of the star sensor, respectively; x and y represent the coordinates of the starlight at the front end of the star sensor, respectively;

[0110] The calculation formula of the complex amplitude transmittance of gratings G1 and G2 is:

[0111]

[0112]

[0113] in, is the m-th order diffraction coefficient of grating G1 at wavelength λ; is the first wavelength of grating G2 at wavelength λ Order diffraction coefficient;

[0114] The transfer function of starlight from the rear surface of G1 to G2 is expressed as:

[0115]

[0116] Among them, f x represents the spatial frequency in the x direction, f y represents the spatial frequency in the y direction;

[0117] The expression of the complex amplitude transmittance of the eight-wedge spectrometer is:

[0118]

[0119] in, 、 They represent the deflection angles of starlight in the x-direction and y-direction after passing through the nth light wedge; rect represents the rectangular function, and the relationship between a and b is as follows: As shown:

[0120]

[0121] The relationship between the wedge angles is as follows: As shown:

[0122] ;

[0123] S1.2. Combine the formula in step S1.1 to obtain The expansion formula is as follows:

[0124]

[0125] S1.3. Design an analysis of the zero-order diffraction image produced by starlight passing through an interferometric star sensor. Based on Parseval's theorem, the energy of the zero-order image produced by starlight passing through the interferometer, the nth optical wedge, and the focusing element is:

[0126]

[0127] Where T is the color temperature of the star; M is the apparent brightness of the star; is the stellar spectral irradiance; is the stellar spectrum range;

[0128] The x- and y-positions of the zero-order image point produced by starlight after it passes through the interferometer, the nth optical wedge, and the focusing assembly are:

[0129]

[0130] Where f represents the focal length of the focusing component;

[0131] When only the 0th and ±1st order diffraction of the grating is considered, let (m,n) represent the image points formed on the image plane by the mth order diffraction produced by G1 and the nth order diffraction produced by G2. Then, after the starlight passes through the interference component, any wedge, and the focusing lens group, it will produce nine diffraction image points: (-1, -1), (-1, 0), (-1, 1), (0, -1), (0, 0), (0, +1), (1, -1), (1, 0), (1, 1). When the incident starlight is wide-spectrum, the dispersion effect of the grating will cause the six high-order diffraction image points (-1, -1), (-1, 0), (0, -1), (0, 1), (1, 0), and (1, 1) to have obvious tails, making their detection more difficult than the three zero-order diffraction image points (-1, 1), (0, 0), and (1, -1). Therefore, only the zero-order diffraction image points produced by the starlight passing through the interferometric star sensor are analyzed.

[0132] S1.4. To facilitate the analysis of zero-order image energy, construct an intermediate variable 、 、 , respectively:

[0133]

[0134]

[0135]

[0136] in, When m is 1 The value of When m is -1 The value of

[0137] Then we have:

[0138]

[0139] At this time, even if the zero-order diffraction of the grating is not 0, Equation (16) is strictly valid, and the expression is:

[0140]

[0141] According to the principle of geometric optics imaging:

[0142]

[0143] At this time, the image point passing through the nth optical wedge coincides with the image point passing through the (n+4)th optical wedge, completing the establishment of the relationship between the incident angle of starlight and the image point energy.

[0144] Furthermore, without increasing the number of image points, the measurement accuracy of the interferometric star sensor in a wide spectral band is improved by introducing an eight-wedge spectrometer.

[0145] S2. Based on the energy distribution of the image points obtained by the detector, the coordinates of the image points on the image plane are extracted using the grayscale weighting method, and the grayscale of each image point is calculated;

[0146] Furthermore, the specific implementation method of step S2 includes the following steps:

[0147] S2.1. First, estimate the background noise threshold using the following formula:

[0148]

[0149] Among them, μ is the grayscale mean of the background, σ is the grayscale standard deviation of the background;

[0150] Perform threshold segmentation on the star map;

[0151] S2.2. Partitioning connected domains of image points based on scanning methods.

[0152] S2.3. Extract the centroids of the image points based on the grayscale weighting method. The centroid coordinates of the four image points are (x1, y1), (x2, y2), (x3, y3), and (x4, y4), and the grayscales of the four image points are g1, g2, g3, and g4, respectively.

[0153] S3 step S2 obtained by the grayscale image point, determine the largest grayscale image point, extract the maximum grayscale image point centroid coordinates;

[0154] Furthermore, the specific implementation method of step S3 is to sort the grayscale of the four pixels extracted in step S2 and find the pixel with the largest grayscale. The centroid coordinates of the pixel are marked as (x max ,y max ).

[0155] S4. Based on the centroid coordinates of the image point with the maximum grayscale obtained in step S4, apply the principles of geometric optics imaging to estimate the starlight incident angle and the starlight phase integer ambiguity;

[0156] Furthermore, the specific implementation method of step S4 is to convert the (x max ,y max ) Bring-in , estimate the starlight incident angle 、 , as shown in the formula As shown:

[0157]

[0158] in, 、 They represent the estimated values ​​of the complementary angles between the starlight and the x-axis and y-axis of the star sensor respectively;

[0159] Substitute the estimated starlight incident angle into the formula With style In the equation, we get a rough phase value , and the phase integer ambiguity Make an estimate, the specific calculation method is as follows As shown:

[0160]

[0161] Here, round means rounding to the nearest integer.

[0162] S5. Based on the image point grayscale obtained in step S2, the main value of the starlight phase is calculated, and the main value of the phase is added to the phase integer ambiguity obtained in step S4 to obtain a high-precision starlight phase;

[0163] Furthermore, the specific implementation method of step S5 is to substitute the grayscale of the four pixels extracted in step S2 into the formula , that is, 、 、 、 , solve the principal value of the starlight phase , add the starlight phase integer ambiguity and the phase main value to obtain the final starlight phase .

[0164] S6. Calculate the high-precision starlight incident angle based on the high-precision starlight phase obtained in step S5 to obtain the high-precision image point centroid coordinates.

[0165] Furthermore, the specific implementation method of step S6 is a combined and , solve the high-precision starlight incident angle α, as shown in Eq. As shown,

[0166]

[0167] Then, based on the principle of geometric imaging, high-precision coordinates of the image point centroid are obtained.

[0168] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0169] Although the present application has been described above with reference to specific embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, as long as there are no structural conflicts, the various features of the embodiments disclosed herein may be combined with each other in any manner, and the omission of an exhaustive description of these combinations in this specification is solely for the sake of space and resource conservation. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A wide-spectrum interferometric star sensor based on an eight-wedge spectrometer, characterized in that: It includes an interference component, an eight-optical wedge spectrometer component, a focusing component, and a detector arranged in sequence; The interference component is two gratings G1 and G2 separated by a certain distance, which are used to modulate the phase of starlight and thus generate interference fringes; The eight-wedge splitter assembly is a wedge array composed of eight wedges, which is used to split the interference fringes into eight parts of fringed light; The focusing component is used to focus the stripe light and form an image at different positions of the detector; The detector is located at the focal plane of the focusing assembly and is used to receive the image of starlight.

2. The wide-spectrum interferometric star sensor based on an eight-wedge spectrometer according to claim 1, characterized in that: The spacing between the gratings G1 and G2 in the interference assembly is z t , the grating period of G1 and G2 is the same, the grating period is p, the z-axis is the optical axis of the optical system, the directions of the lines of the two gratings are perpendicular to the optical axis, and the angle between the directions of the lines of the two gratings and the y-axis is ɛ, satisfying , where b is the width of a single wedge and the ruling direction is symmetric about the y-axis.

3. The broadband interferometric star sensor based on the eight-wedge spectrometer according to claim 2, characterized in that: The eight wedges of the eight-wedge spectrometer are arranged along the y-axis to deflect eight portions of starlight in different directions. The dimensions of each of the eight wedges are a×b, satisfying a=8b, where a and b represent the length of the wedge along the x-direction and the length of the wedge along the y-direction, respectively. The rear surface of the eight-wedge spectrometer serves as the entrance pupil of the broadband interferometric star sensor based on the eight-wedge spectrometer.

4. A method for locating the centroid of a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer assembly, implemented by the wide-spectrum interferometric star sensor based on an eight-wedge spectrometer assembly as claimed in any one of claims 1 to 3, characterized in that: The steps include: S1. Construct a model for the relationship between the incident angle of starlight and the image point energy of a broadband interferometric star sensor based on an eight-wedge spectrometer. S2. Based on the energy distribution of the image points obtained by the detector, the coordinates of the image points on the image plane are extracted using the grayscale weighting method, and the grayscale of each image point is calculated; S3 step S2 obtained by the grayscale image point, determine the largest grayscale image point, extract the maximum grayscale image point centroid coordinates; S4. Based on the centroid coordinates of the image point with the maximum grayscale obtained in step S4, apply the principles of geometric optics imaging to estimate the starlight incident angle and the starlight phase integer ambiguity; S5. Based on the image point grayscale obtained in step S2, the main value of the starlight phase is calculated, and the main value of the phase is added to the phase integer ambiguity obtained in step S4 to obtain a high-precision starlight phase; S6. Calculate the high-precision starlight incident angle based on the high-precision starlight phase obtained in step S5 to obtain the high-precision image point centroid coordinates.

5. The centroid positioning method of a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer according to claim 4, characterized in that: The specific implementation method of step S1 includes the following steps: S1.

1. Calculation of the angular spectrum of starlight after passing through interferometers and spectrometers based on angular spectrum propagation theory , the calculation formula is: ； in, represents the Fourier transform operation; represents the complex amplitude of starlight at the front end of the star sensor; represents the complex amplitude transmittance of grating G1; is the transfer function of starlight from the rear surface of G1 to G2; represents the complex amplitude transmittance of grating G2; represents the complex amplitude transmittance of the eight-wedge spectrometer; Represents the convolution operation; The calculation formula of the complex amplitude of starlight at the front end of the star sensor is: ； in, represents the amplitude of starlight; j represents the imaginary unit; λ represents the wavelength of starlight; α and β represent the complementary angles between the starlight and the x-axis and y-axis of the star sensor, respectively; x and y represent the coordinates of the starlight at the front end of the star sensor, respectively; The calculation formula of the complex amplitude transmittance of gratings G1 and G2 is: ； ； in, is the m-th order diffraction coefficient of grating G1 at wavelength λ; is the first wavelength of grating G2 at wavelength λ Order diffraction coefficient; The transfer function of starlight from the rear surface of G1 to G2 is expressed as: ； Among them, f x represents the spatial frequency of starlight in the x direction, f y represents the spatial frequency of starlight in the y direction; The expression of the complex amplitude transmittance of the eight-wedge spectrometer is: ； in, 、 They represent the deflection angles of starlight in the x-direction and y-direction after passing through the nth light wedge; rect represents the rectangular function, and the relationship between a and b is as follows: As shown: ； The relationship between the wedge angles is as follows: As shown: ； S1.

2. Combine the formula in step S1.1 to obtain The expansion formula is as follows: ； S1.

3. Design an analysis of the zero-order diffraction image produced by starlight passing through an interferometric star sensor. Based on Parseval's theorem, the energy of the zero-order image produced by starlight passing through the interferometer, the nth optical wedge, and the focusing element is: ； in, is the stellar spectrum range; The x- and y-positions of the zero-order image point produced by starlight after it passes through the interferometer, the nth optical wedge, and the focusing assembly are: ； Where f represents the focal length of the focusing component; S1.

4. To facilitate the analysis of zero-order image energy, construct an intermediate variable 、 、 , respectively: ； ； ； in, When m is 1 The value of When m is -1 The value of Then we have: ； At this time, even if the zero-order diffraction of the grating is not 0, Equation (16) is strictly valid, and the expression is: ； According to the principle of geometric optics imaging: ； At this time, the image point formed by the nth optical wedge coincides with the image point formed by the (n+4)th optical wedge, completing the establishment of the relationship between the incident angle of starlight and the image point energy.

6. The centroid positioning method of a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer according to claim 5, characterized in that: The specific implementation method of step S2 includes the following steps: S2.

1. First, estimate the background noise threshold using the following formula: ； Among them, μ is the grayscale mean of the background, σ is the grayscale standard deviation of the background; Perform threshold segmentation on the star map; S2.

2. Partitioning connected domains of image points based on scanning methods. S2.

3. Extract the centroids of the image points based on the grayscale weighting method. The centroid coordinates of the four image points are (x1, y1), (x2, y2), (x3, y3), and (x4, y4), and the grayscales of the four image points are g1, g2, g3, and g4, respectively.

7. The centroid positioning method of a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer according to claim 6, characterized in that: The specific implementation method of step S3 is to sort the grayscale of the four pixels extracted in step S2 and find the pixel with the largest grayscale. The centroid coordinates are marked as (x max ,y max ).

8. The centroid positioning method of a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer according to claim 7, characterized in that: The specific implementation method of step S4 is to convert the (x max ,y max ) Bring-in , estimate the starlight incident angle 、 , as shown in the formula As shown: ； in, 、 They represent the estimated values ​​of the complementary angles between the starlight and the x-axis and y-axis of the star sensor respectively; Substitute the estimated starlight incident angle into the formula With style In the equation, we get a rough phase value , and the phase integer ambiguity Make an estimate, the specific calculation method is as follows As shown: ； Here, round means rounding to the nearest integer.

9. The centroid positioning method of a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer according to claim 8, characterized in that: The specific implementation method of step S5 is to substitute the grayscale of the four pixels extracted in step S2 into the formula , that is, 、 、 、 , solve the principal value of the starlight phase , add the starlight phase integer ambiguity and the phase main value to obtain the final starlight phase .

10. The centroid positioning method of a wide-spectrum interferometric star sensor based on an eight-wedge spectrometer according to claim 9, characterized in that: The specific implementation method of step S6 is a combined and , solve the high-precision starlight incident angle α, as shown in Eq. As shown, ； Then, based on the principle of geometric imaging, high-precision coordinates of the image point centroid are obtained.

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