Seamless spectral measurement method for spliced mirror surface

Abstract

The invention relates to the technical field of spliced telescopes, and particularly provides a spliced mirror surface seamless spectral measurement method, which comprises the following steps: irradiating a spliced mirror surface by using incident light, selecting two sub-mirrors by using an aperture masking method, opening aperture channels of the two selected sub-mirrors, closing aperture channels of other sub-mirrors, and carrying out spectral measurement on the spliced mirror surface. Performing dispersion on two beams of reflected light reflected by the two selected sub-mirrors to obtain two beams of spectral dispersion light, performing interference on the two beams of spectral dispersion light, expanding interference fringes with different wavelengths in a direction perpendicular to dispersion, performing detection to obtain a two-dimensional interference spectrum, performing pose adjustment on the two selected sub-mirrors to realize spectrum alignment, and performing spectrum alignment. The spectrums of all the sub-mirrors of the spliced mirror surface are aligned through iteration, aperture channels of all the sub-mirrors are opened, and the seamless spectrum of the spliced mirror surface can be measured. According to the invention, the seamless spectrum of the spliced mirror surface with high signal-to-noise ratio, good continuity and resolution close to diffraction limit can be obtained.

Description

Technical Field

[0001] This invention belongs to the field of spliced ​​telescope technology, and particularly relates to a seamless spectral measurement method for spliced ​​mirrors. Background Technology

[0002] Currently, with the development of telescope detection applications, in order to break through the limit of single mirror aperture of telescopes, the splicing primary mirror technology is generally adopted. That is, multiple independent sub-mirrors are spliced ​​together to form an ultra-large aperture reflecting mirror, which solves the problem that traditional solid mirrors cannot achieve ultra-large aperture fabrication.

[0003] However, due to unavoidable errors in the splicing and installation of individual sub-mirrors, spliced ​​mirrors inevitably suffer from non-confocal and non-co-phase issues. When performing spectral measurements on spliced ​​mirrors, these splicing errors cause misalignment of the dispersive spectra of each sub-mirror, resulting in a blurred spectrum of the entire spliced ​​mirror, making it impossible to obtain a clear spectral line. Furthermore, the dispersive spectra of different sub-mirrors lack alignment criteria in the continuous direction, making precise alignment difficult and severely affecting spectral continuity, resolution, and quantitative accuracy. Summary of the Invention

[0004] In view of this, the present invention aims to provide a seamless spectral measurement method for spliced ​​mirrors. By adjusting adjacent sub-mirrors sequentially through a masking aperture method and aligning each spectral band through dispersive interference, the present invention solves the problem that in traditional methods, the light from all sub-mirrors is detected simultaneously, resulting in multiple misaligned spectral bands overlapping and becoming blurred, making it impossible to detect a clear spectral line. Furthermore, to solve the problem of spectral band continuity alignment, the present invention achieves accurate spectral alignment through interference characteristics.

[0005] To achieve the above objectives, the technical solution created by this invention is implemented as follows: This invention provides a seamless spectral measurement method for spliced ​​mirror surfaces, comprising: S1: Illuminate the splicing mirror surface with incident light, select two sub-mirrors by masking the aperture, open the aperture channels of the selected two sub-mirrors, and close the aperture channels of the other sub-mirrors; S2: Dispers the two reflected beams from the two selected sub-mirrors to obtain two spectral dispersed beams; S3: Interference is performed on two beams of spectral dispersion light, and interference fringes of different wavelengths are spread out in the direction perpendicular to dispersion. A two-dimensional interference spectrum is obtained by detection, where one dimension represents the wavelength and the other dimension represents the spatial distribution of interference fringes of each wavelength. S4: Adjust the pose of the two selected sub-mirrors to maximize the contrast of the interference fringes across the entire two-dimensional interference spectrum, thus completing the spectral alignment of the two selected sub-mirrors. S5: Iterate through S1-S4 to align the spectra of all sub-mirrors in the spliced ​​mirror and open the aperture channels of all sub-mirrors to measure the seamless spectrum of the spliced ​​mirror.

[0006] Preferably, the spliced ​​mirror surface is illuminated by incident light, including: Starlight is used as the incident light to illuminate the spliced ​​mirror surface; Alternatively, a broadband light source can be placed in front of the splicing mirrors via optical fiber to provide incident light.

[0007] Preferably, two sub-mirrors are selected using a masking aperture method, opening the aperture channels of the selected two sub-mirrors and closing the aperture channels of other sub-mirrors, including: All sub-mirrors on the spliced ​​mirror surface are coded, and any two sub-mirrors are selected to block the other sub-mirrors, preventing them from reflecting incident light.

[0008] Preferably, the two selected sub-mirrors are adjacent sub-mirrors.

[0009] Preferably, a dispersive prism for dispersing light and a cylindrical lens for converging light are sequentially arranged in the transmission optical path of the two reflected beams reflected by the two selected sub-mirrors.

[0010] Preferably, two beams of spectral dispersion light are input into an interferometer for spectral interference.

[0011] Preferably, the adjustment process to maximize the contrast of the interference fringes across the entire two-dimensional interference spectrum is as follows: with the goal of maximizing the average contrast of the interference fringes across the entire spectrum or a selected spectrum, a contrast threshold is set. When the poses of the two selected sub-mirrors are adjusted so that the average contrast of the interference fringes across the entire spectrum or a selected spectrum is greater than or equal to the contrast threshold, the spectra of the two sub-mirrors are considered to be aligned.

[0012] Preferably, a detector is used to collect two-dimensional interference spectra.

[0013] Preferably, before S1, the method further includes: performing confocal collimation on the incident light and wavelength calibration on the optical path to establish a mapping relationship between the pixel position and wavelength on the detector target surface.

[0014] Preferably, during the pose adjustment of the two selected sub-mirrors, the confocal state of the spliced ​​mirror surface is maintained by a curvature sensor.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects: This invention employs a masked aperture method to address the problem of overlapping and blurring of multiple misaligned spectral bands caused by simultaneous spectral detection of all sub-mirrors in traditional methods, making it impossible to detect a clear spectral line. By utilizing the contrast of interference fringes across the entire spectrum as an alignment criterion and leveraging the sensitivity of interference fringes to phase misalignment, the invention solves the problem of difficulty in aligning the spectrum along continuous directions. After aligning the spectra of all sub-mirrors through masked aperture and iterative coding, seamless and precise superposition of the spectra of all sub-mirrors at the detector pixel level can be achieved. Ultimately, a seamless spectrum with high signal-to-noise ratio, good continuity, and resolution close to the diffraction limit is obtained, greatly enhancing the observation capabilities of the mosaic telescope. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart of a seamless spectral measurement method for spliced ​​mirrors provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the optical path for dispersion of two reflected beams according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a spliced ​​telescope for spectral measurement according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a structure for simulating a distant light source to perform spectral measurements on a spliced ​​telescope, according to an embodiment of the present invention.

[0017] The reference numerals in the figures include: Sub-mirror 1, dispersive prism 2, cylindrical lens 3, light source 4, optical fiber 5, fast reflector 6, UAV 7. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be 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 for explaining the invention and do not constitute a limitation thereof. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the invention. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, some operations related to the invention are not shown or described in the specification. This is to avoid obscuring the core parts of the invention with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; the relevant operations can be fully understood based on the description in the specification and general technical knowledge in the art.

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined to form various implementations. Furthermore, the order of the steps or actions in the method description can be changed or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] The optical mirrors of a mosaic telescope mainly consist of a primary mirror and secondary mirrors. The primary mirror is used to collect light incident from the observed target. Because the primary mirror has a large aperture, a mosaic mirror structure is used. This mosaic mirror structure is composed of numerous sub-mirrors. Due to inherent errors in the mosaic process, it's impossible to ensure that each sub-mirror is in an ideal position, preventing them from becoming confocal and in phase. Therefore, when performing spectral measurements using the mosaic mirror structure, the mosaic errors of each sub-mirror can cause misalignment in their dispersive spectra, resulting in a blurred dispersive spectrum. To align the dispersive spectra of all sub-mirrors and present them as a single, clear spectral line, please refer to [link to relevant documentation]. Figure 1 In one embodiment of the present invention, a method for seamless spectral measurement of spliced ​​mirrors is provided, comprising the following steps: S1: Illuminate the splicing mirror surface with incident light, select two sub-mirrors by masking the aperture, open the aperture channels of the selected two sub-mirrors, and close the aperture channels of the other sub-mirrors; S2: Dispers the two reflected beams from the two selected sub-mirrors to obtain two spectral dispersed beams; S3: Interference is performed on two beams of spectral dispersion light, and interference fringes of different wavelengths are spread out in the direction perpendicular to dispersion. A two-dimensional interference spectrum is obtained by detection, where one dimension represents the wavelength and the other dimension represents the spatial distribution of interference fringes of each wavelength. S4: Adjust the pose of the two selected sub-mirrors to maximize the contrast of the interference fringes across the entire two-dimensional interference spectrum, thus completing the spectral alignment of the two selected sub-mirrors. S5: Iterate through S1-S4 to align the spectra of all sub-mirrors in the spliced ​​mirror and open the aperture channels of all sub-mirrors to measure the seamless spectrum of the spliced ​​mirror.

[0024] like Figure 2As shown, in step S1, the splicing mirror is illuminated by incident light. To avoid the mixing and superposition of the spectra of multiple sub-mirrors 1, which would cause the spectra of the splicing mirror to be misaligned, this embodiment of the invention uses a masking aperture method to encode all sub-mirrors 1 on the splicing mirror and select only two sub-mirrors 1 at a time, usually two adjacent sub-mirrors 1. Only the aperture channels of these two selected sub-mirrors 1 are opened, while the aperture channels of other sub-mirrors 1 are closed. That is, by blocking or other means, only these two selected sub-mirrors 1 reflect the incident light, simplifying the complex multipath problem into a pure two-beam problem, and performing subsequent processing on the two reflected beams of light reflected by the two selected sub-mirrors.

[0025] As an optional embodiment, before the incident light illuminates the splicing mirror, it is also necessary to perform confocal collimation on the incident light to ensure that all sub-mirrors on the splicing mirror are in a confocal state, and to perform wavelength calibration on the optical path using a spectrometer to establish the mapping relationship between the pixel position and the corresponding wavelength on the detector target surface used to obtain the spectrum of the main mirror.

[0026] As an optional embodiment, such as Figure 3 As shown, for incident light, a fixed carbon fiber rod can be set at the front end of the splicing telescope, and an optical fiber 5 can be set on the carbon fiber rod. The optical fiber 5 is connected to the light source 4. The light source 4 is a broadband light source. The light provided by the light source 4 is transmitted through the optical fiber 5 to the light outlet position set on the carbon fiber rod, and then shines on the main mirror of the splicing telescope through the light outlet. This can achieve fixed illumination of the incident light. This method is suitable for the initial assembly or testing stage of the main mirror of the splicing telescope in the laboratory.

[0027] As an optional embodiment, such as Figure 4 As shown, for incident light, during field testing, long-distance light incidence simulation can be performed using a drone 7. Light from the light source 4 is transmitted to the drone 7 via fiber optic cable 5, and then shines through the output port on the drone 7 onto the primary mirror of the splicing telescope. This allows for long-distance illumination of the incident light. This method is suitable for testing and calibration after the primary mirror of the splicing telescope has been assembled and adjusted in the field. Because the drone 7 experiences mechanical vibration, the incident light will also vibrate. Therefore, a fast-reflecting mirror needs to be further installed in the optical path to suppress beam vibration.

[0028] As an optional implementation, once the spliced ​​telescope is deployed and put into practical use, the incident starlight can be used directly as the incident light.

[0029] like Figure 2As shown, in step S2, the two reflected beams from the selected two sub-mirrors need to be dispersed. Specifically, a dispersive prism 2 and a cylindrical lens 3 are sequentially placed along the propagation path of the two reflected beams. The dispersive prism 2 can be a triangular prism, used to disperse the reflected light, achieve spectral band separation, and obtain two beams of spectrally dispersed light, whose light spots appear as spectral bands spreading along the dispersion direction. The cylindrical lens 3 is a semi-cylindrical lens, whose axis is the same as the opposite direction of dispersion. Through the cylindrical lens 3, the two beams of spectrally dispersed light can be converged in a direction perpendicular to the opposite direction of dispersion, which facilitates subsequent interference.

[0030] In step S3, the two spectrally dispersed beams, after dispersion and convergence processing, are interfered. Specifically, an interference grating can be used, or the light can be directly fed into a spectrometer. This causes interference of beams with the same wavelength band to occur, resulting in interference fringes of different wavelengths spreading in a direction perpendicular to dispersion. The direction of the interference fringes is perpendicular to the dispersion direction. At this point, a two-dimensional interference spectrum can be detected, where one dimension represents the wavelength and the other represents the spatial distribution of interference fringes at each wavelength. The contrast of the fringes reflects the optical path difference between the two spectrally dispersed beams, and further reflects the co-phase state of the two selected sub-mirrors 1. Because interference fringes are highly sensitive to phase difference, any slight tilt or forward / backward deviation between the two selected sub-mirrors 1 will affect their phase difference, thereby changing the intensity of the superimposed light. This is manifested in the interference fringes as a change in the contrast between bright and dark fringes, transforming the microscopic spatial deviation into a macroscopic change in light intensity. Furthermore, the embodiments of the present invention can obtain interference fringes of multiple wavelengths by first dispersing and then interfering. Adjusting the sub-mirror 1 according to the two-dimensional interference spectrum can make the fringes of all wavelengths as clear as possible, so that all wavelengths are in a co-phase state, avoiding the inability to achieve precise alignment in the direction of spectral continuity during the spectral alignment process.

[0031] In step S4, the pose of the two selected sub-mirrors 1 can be adjusted based on the two-dimensional interference spectrum to maximize the contrast of the interference fringes across the entire spectral band, thus completing the spectral alignment of the two selected sub-mirrors 1. During the contrast maximization process, an objective function can be set, with the goal of maximizing the average interference fringe contrast across the entire spectral band or a selected band. A contrast threshold is set, and the objective function requires that the average interference fringe contrast across the entire spectral band or a selected band be greater than or equal to the contrast threshold. When the pose of sub-mirrors 1 is adjusted and the objective function is satisfied, the two sub-mirrors can be considered to be in phase and spectrally aligned.

[0032] It is important to note that during the position adjustment of sub-mirror 1, the splicing mirror surface needs to be maintained in confocal condition by the curvature sensor of the splicing telescope itself to prevent the position adjustment of sub-mirror 1 from disrupting the confocal state of the splicing mirror surface.

[0033] As an optional embodiment, during the spectral alignment process, polynomial fitting can also be performed on the detected two-dimensional interference spectrum. First, an Nth-order polynomial is used for fitting to extract the interference peak position; then, an N+1th-order polynomial is used for fitting to extract the interference peak position again. If the interference peak position remains consistent in polynomial fitting of different orders (≥3 orders), then the interference peak is considered a stable true peak. The contrast of the interference fringes of the stable true peak is used as the alignment criterion for adjusting the pose of the sub-mirror.

[0034] In step S5, the process is iterated according to steps S1 to S4. Two sub-mirrors 1 are reselected and adjusted using the masking aperture method until all sub-mirrors 1 achieve spectral alignment. At this point, the aperture channels of all sub-mirrors 1 can be opened, and all sub-mirrors 1 are in a confocal and co-phase state. At this time, a spectrometer can be used to perform seamless spectral detection on the spliced ​​mirror surface, solving the problem of traditional spliced ​​telescopes being unable to obtain clear and continuous spectra.

[0035] In summary, the above description is merely a preferred embodiment of this specification and is not intended to limit the scope of protection of this specification. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this specification should be included within the scope of protection of this specification.

[0036] The systems, apparatuses, modules, or units described in one or more of the above embodiments may be implemented by a computer chip or entity, or by a product having a certain function. A typical implementation device is a computer. Specifically, a computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0037] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0038] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

Claims

1. A method for seamless spectral measurement of spliced ​​mirror surfaces, characterized in that, include: S1: Illuminate the splicing mirror surface with incident light, select two sub-mirrors by masking the aperture, open the aperture channels of the selected two sub-mirrors, and close the aperture channels of the other sub-mirrors; S2: Dispers the two reflected beams from the two selected sub-mirrors to obtain two spectral dispersed beams; S3: Interference is performed on two beams of spectral dispersion light, and interference fringes of different wavelengths are spread out in the direction perpendicular to dispersion. A two-dimensional interference spectrum is obtained by detection, where one dimension represents the wavelength and the other dimension represents the spatial distribution of interference fringes of each wavelength. S4: Adjust the pose of the two selected sub-mirrors to maximize the contrast of the full-band interference fringes of the two-dimensional interference spectrum, and complete the spectral alignment of the two selected sub-mirrors. S5: Iterate through S1-S4 to align the spectra of all sub-mirrors in the spliced ​​mirror surface, open the aperture channels of all sub-mirrors, and the seamless spectrum of the spliced ​​mirror surface can be measured.

2. The seamless spectral measurement method for spliced ​​mirror surfaces according to claim 1, characterized in that, The method of illuminating the spliced ​​mirror surface with incident light includes: Starlight is used as the incident light to illuminate the spliced ​​mirror surface; Alternatively, a broadband light source can be placed in front of the splicing mirror surface via an optical fiber to provide incident light.

3. The seamless spectral measurement method for spliced ​​mirror surfaces according to claim 1, characterized in that, The method of selecting two sub-mirrors using a masking aperture method, opening the aperture channels of the selected two sub-mirrors, and closing the aperture channels of other sub-mirrors includes: All sub-mirrors on the spliced ​​mirror surface are coded, and any two sub-mirrors are selected to block the other sub-mirrors, preventing them from reflecting incident light.

4. The seamless spectral measurement method for spliced ​​mirror surfaces according to claim 1, characterized in that, The two selected sub-mirrors are adjacent sub-mirrors.

5. The seamless spectral measurement method for spliced ​​mirror surfaces according to claim 1, characterized in that, A dispersive prism for dispersing light and a cylindrical lens for converging light are sequentially arranged along the transmission optical path of the two reflected beams from the two selected sub-mirrors.

6. The seamless spectral measurement method for spliced ​​mirror surfaces according to claim 1, characterized in that, Two beams of spectral dispersion light are input into an interferometer for spectral interference.

7. The seamless spectral measurement method for spliced ​​mirrors according to claim 1, characterized in that, The adjustment process to maximize the contrast of the interference fringes across the entire two-dimensional interference spectrum is as follows: with the goal of maximizing the average contrast of the interference fringes across the entire spectrum or a selected spectrum, a contrast threshold is set. When the poses of the two selected sub-mirrors are adjusted so that the average contrast of the interference fringes across the entire spectrum or a selected spectrum is greater than or equal to the contrast threshold, the spectra of the two sub-mirrors are considered to be aligned.

8. The seamless spectral measurement method for spliced ​​mirror surfaces according to claim 1, characterized in that, The two-dimensional interference spectrum was acquired using a detector.

9. The seamless spectral measurement method for spliced ​​mirror surfaces according to claim 8, characterized in that, Before S1, the method further includes: performing confocal collimation on the incident light and wavelength calibration on the optical path to establish a mapping relationship between the pixel position and wavelength on the detector target surface.

10. The seamless spectral measurement method for spliced ​​mirror surfaces according to claim 1, characterized in that, During the pose adjustment of the two selected sub-mirrors, the confocal state of the spliced ​​mirror surface is maintained by a curvature sensor.

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