Simulation Analysis Methods for Large-Aperture, Wide-Field-of-View Telescopes Based on Photon Accumulation

Abstract

This invention belongs to the field of astronomical telescopes, and particularly relates to a simulation analysis method for large-aperture, wide-field-of-view telescopes based on photon accumulation. The method includes: setting up photon streams with random incident characteristics at different locations within the large-aperture, wide-field-of-view telescope; reflecting the photon streams at the reflecting surfaces of each mirror of the large-aperture, wide-field-of-view telescope; defining a measurement area on the detector target surface of the large-aperture, wide-field-of-view telescope; counting photons arriving at the measurement area on the detector target surface to simulate the imaging signal; simultaneously, statistically analyzing photons arriving at non-measurement areas on the detector target surface to simulate background noise; simulating stray light from the off-axis field of view based on the simulated imaging signal and background noise; and determining the signal-to-noise ratio of the large-aperture, wide-field-of-view telescope based on the simulation results. This invention can accurately simulate the propagation path and energy distribution of photons in a large-aperture, wide-field-of-view telescope, significantly improving the prediction accuracy of system imaging performance and stray light effects.

Description

Technical Field

[0001] This invention belongs to the field of astronomical telescope technology, and particularly relates to a simulation analysis method for large-aperture, large-field telescopes based on photon accumulation. Background Technology

[0002] Large-aperture, wide-field optical survey telescopes (LASTs) are core equipment for exploring the universe, and their performance is closely related to their aperture: resolution is directly proportional to aperture, while light-gathering capacity is directly proportional to the square of the aperture. By increasing the system aperture, the sensitivity and resolution of survey observations can be significantly improved, thereby obtaining higher-quality deep-field cosmic data and providing crucial support for exploring scientific questions such as cosmic structure and celestial evolution.

[0003] Currently, the world's mainstream large-aperture, wide-field-of-view survey instruments have apertures ranging from 2 to 8 meters. Representative instruments include: the SDSS telescope with a 2.5-meter aperture, the Pan-STARRS telescope with a 1.8-meter aperture, the DEcam survey instrument with a 4-meter primary mirror, the telescope corresponding to the Subaru HyperPrime survey, and the LSST telescope at the Lavie Rubin Observatory with an 8.4-meter aperture. These instruments, leveraging their performance advantages, have been conducting in-depth explorations in the field of time-domain astronomy, enabling precise observations of targets such as active galactic nuclei, near-Earth asteroids, and gravitational lensing. They provide rich data support for constructing accurate cosmological models and answering major fundamental scientific questions such as "one black, two dark, and three origins" (i.e., black holes, dark matter, dark energy, and the origin of the universe, celestial bodies, and life).

[0004] However, with the deepening of astronomical research, higher demands have been placed on the detection of targets such as the deep-field universe, exoplanets, and near-Earth asteroids. This requires not only further improvements in detection resolution and sensitivity but also the realization of collaborative sky surveys covering large areas, multiple messengers, and multiple spectral bands. This demand has driven the development of larger aperture survey instruments, with 10-meter-class large-aperture, wide-field-of-view survey telescopes becoming the core research and development direction for next-generation equipment. However, limited by manufacturing processes, the aperture limit of a single optical mirror is 8 meters (such as the VLT telescope, Subaru telescope, and GIMINI telescope, all of which use single mirrors of this size). 10-meter-class telescope mirrors cannot be manufactured in a single step and must be constructed using splicing technology. Currently, the mainstream mirror splicing methods are mainly divided into two categories: one is the sparse aperture form that precisely aligns multiple independent telescopes to achieve a common phase (such as the GMT telescope); the other is the spliced ​​mirror form that approximates a continuous mirror by reducing the seam effect (such as the TMT telescope and ELT telescope).

[0005] The Maunakea Spectroscopic Explorer (MES), a next-generation large-aperture, wide-field survey telescope led by the University of Hawaii, further pushes the performance boundaries of existing instruments. Its field of view reaches 1.5 square degrees, its primary mirror diameter is 11.25 meters, it employs a prime focus optics design, and aberration correction is achieved through a lens group (the first lens has a diameter of 1.3 meters). Compared to traditional 10-meter-class mosaic telescopes like Keck, the MES exhibits significant differences, with its field of view reaching the "degree" scale and a faster focal ratio (F-number between 1 and 2), making aberration correction impossible through adjustments to the back-end optical path. Simultaneously, the MES system faces unique technical challenges: the spatial frequency characteristics of each mirror are extremely strongly coupled, requiring extremely high residual accuracy in active optical correction. This poses unprecedented challenges to the aberration sensing accuracy and dynamic control capabilities of the optical system, becoming a key bottleneck restricting performance breakthroughs for 10-meter-class large-aperture, wide-field survey telescopes. Summary of the Invention

[0006] In view of this, the present invention aims to provide an analytical method that can efficiently simulate the photon transmission, aberration response and stray light effects in large-aperture, large-field-of-view telescopes.

[0007] To achieve the above objectives, the technical solution created by this invention is implemented as follows:

[0008] A simulation analysis method for large-aperture, wide-field telescopes based on photon accumulation includes the following steps:

[0009] S1: Photon streams with random incident characteristics are set at different positions of a large-aperture, large-field-of-view telescope; the photon streams are reflected by the reflecting surfaces of each mirror of the large-aperture, large-field-of-view telescope; wherein, the optical surface shape of each mirror is different.

[0010] S2: Delineate the measurement area on the detector target surface of the large-aperture, wide-field telescope, count the photons arriving at the measurement area on the detector target surface to simulate the imaging signal; at the same time, count the photons arriving at the non-measurement area on the detector target surface to simulate background noise.

[0011] S3: Based on the imaging signal and background noise simulated in step S2, simulate stray light from the off-axis field of view, and determine the signal-to-noise ratio of the large-aperture, large-field telescope based on the simulation results.

[0012] Furthermore, the randomly incident photon stream exhibits a normal or Poisson distribution.

[0013] Furthermore, prior to step S1, the following steps are also included:

[0014] An analytical model for multi-mirror correction is constructed based on standard spherical wave and Fourier optics theory.

[0015] Furthermore, the establishment of the analytical model specifically includes:

[0016] The light source is described using the complex amplitude expression of a spherical wave under the paraxial approximation.

[0017] According to Fresnel diffraction law, calculate the complex amplitude distribution of the light field after it has been modulated by at least two mirrors;

[0018] The final light intensity distribution on the detector is obtained by multiplying the complex amplitude distribution with its conjugate.

[0019] Furthermore, the analytical model adopts the following wavefront optical field distribution model under a single wavelength:

[0020] ;

[0021] in, The wavefront light field distribution under a single wavelength, For wavelength, The amplitude of a single phase spatial frequency component. The pupil coordinate vector Spatial frequency domain coordinates, For the first Defocus amount per field of view It is the imaginary unit.

[0022] Furthermore, the curvature of the wavefront phase is proportional to the difference in light intensity along the optical axis:

[0023] ;

[0024] in, The energy distribution before the focal plane, The energy distribution after fozing, For the initial phase, The curvature of the wavefront phase.

[0025] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0026] 1. High-precision simulation capability: By setting up random incident photon flow and performing reflection simulation on each optical surface, combined with elastic incidence and surface shape influence analysis, it can accurately simulate the propagation path and energy distribution of photons in large-aperture, large-field-of-view telescopes, significantly improving the prediction accuracy of system imaging performance and stray light influence.

[0027] 2. Comprehensive evaluation of system performance: Photons in the detector measurement area are counted and photons in the non-measurement area are statistically analyzed, realizing the synchronous evaluation of effective signal and background noise, and providing a reliable basis for accurate judgment of signal-to-noise ratio (SNR).

[0028] 3. High-efficiency stray light analysis: It can simulate the impact of stray light such as moonlight and starlight incident off-axis on the system. It is especially suitable for performance evaluation of large field of view and large aperture telescopes in complex observation environments. It helps to optimize the light shielding structure and optical design and reduce stray light interference.

[0029] 4. Adapting to the design requirements of next-generation telescopes: In view of the characteristics of large field of view, fast focal ratio and high aberration correction of 10-meter and above mosaic mirror telescopes (such as MES, TMT, ELT, etc.), the analytical model and wavefront aberration response analysis method provided by this invention provide theoretical support and technical path for multi-mirror collaborative correction and active optical control.

[0030] 5. Combination of analytical model and numerical simulation: Based on Fourier optics theory and wavefront sensing method, an analytical model of the system's multi-mirror correction process was constructed. Combined with photon-level numerical simulation, the entire chain simulation from wavefront phase to detector light intensity was realized, which has both theoretical rigor and engineering practicality. Attached Figure Description

[0031] 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:

[0032] Figure 1 A schematic flowchart illustrating the simulation analysis method for a large-aperture, large-field telescope based on photon accumulation, as described in an embodiment of the present invention.

[0033] Figure 2 A schematic diagram of the structure of the large-aperture, large-field-of-view telescope described in an embodiment of the present invention;

[0034] Figures 3-6 A schematic diagram illustrating the simulation effect of the large-aperture, large-field-of-view telescope simulation analysis method based on photon accumulation as described in the embodiments of the present invention.

[0035] Explanation of reference numerals in the attached figures:

[0036] Primary mirror 1, secondary mirror 2, third mirror 3, detector 4. Detailed Implementation

[0037] 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 merely illustrative of the invention and do not constitute a limitation thereof.

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0039] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," 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.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" 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.

[0041] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] like Figure 1 As shown, this invention provides a simulation analysis method for large-aperture, wide-field telescopes based on photon accumulation, comprising the following steps:

[0043] S1: Photon streams with random incident characteristics are set at different positions of a large-aperture, large-field-of-view telescope; the photon streams are reflected by the reflecting surfaces of each mirror of the large-aperture, large-field-of-view telescope; wherein, the optical surface shape of each mirror is different.

[0044] like Figure 2 The large-aperture, wide-field telescope shown includes a primary mirror 1, a secondary mirror 2, a third mirror 3, and a detector 4. Incident light first enters the primary mirror 1, is reflected by the primary mirror 1 to the secondary mirror 2, is reflected by the secondary mirror 2 to the third mirror 3, and is finally reflected by the third mirror 3 to the detector 4. The optical surfaces of the primary mirror 1, secondary mirror 2, and third mirror 3 are all different.

[0045] The primary mirror 1 can be a spliced ​​primary mirror composed of multiple sub-mirrors. At least one sub-mirror is tilted so that its edge forms a tilt angle to reflect the incident light beam. The reflected light beams at the tilt angle are geometrically calculated and accumulated, and finally the effects of reflections from non-imaging surfaces are calculated and analyzed.

[0046] Cumulative simulations were performed on the coherence (including diffraction and interference) of light generated at the edges of the sub-mirrors, and the simulation results were obtained at the interface between the sub-mirrors. Figures 3-5 As shown.

[0047] An optical fiber is connected between the three mirrors (3) and the detector (4). One end of the fiber is connected to the three mirrors (3), and the other end is connected to the detector (4). The light beam reflected by the three mirrors (3) enters the optical fiber for transmission and finally reaches the detector (4). The order of the mode field is determined based on the numerical aperture of the optical fiber. The beam distribution within the optical fiber is fitted based on the mode field and the substrate to simulate the order of the mode field within the optical fiber. The simulation results are as follows: Figure 6 As shown.

[0048] When a randomly incident photon stream is incident on a large-aperture, wide-field telescope in a homogeneous state with many photons, the number of photons follows a normal distribution over time. When a randomly incident photon stream is incident on a large-aperture, wide-field telescope in a non-homogeneous state with few photons, the number of photons follows a Poisson distribution over time.

[0049] S2: Delineate the measurement area on the detector target surface of the large-aperture, large-field-of-view telescope, count the photons arriving at the measurement area on the detector target surface to simulate the imaging signal; at the same time, count the photons arriving at the non-measurement area on the detector target surface to simulate background noise.

[0050] S3: Based on the imaging signal and background noise simulated in step S2, simulate stray light from the off-axis field of view, and determine the signal-to-noise ratio of the large-aperture, large-field telescope based on the simulation results.

[0051] Before step S1, the following steps are also included:

[0052] Based on standard spherical waves and Fourier optics theory, an analytical expression is obtained to show the influence of non-pupil surface pose, surface shape, and other features on wavefront aberration response. Furthermore, an analytical model of the system's multi-mirror correction process is established based on this. Specifically:

[0053] In scalar electromagnetic field terms, the complex amplitude generated by the spherical wave emitted by the paraxial approximation light source can be represented by equation (1).

[0054] (1);

[0055] in, Let A be the initial phase, where A represents the uniform amplitude distribution in the plane under the paraxial approximation, and x and y are the pupil coordinates. According to Fresnel diffraction law, the complex optical field after two mirror adjustments is shown in equation (2):

[0056] (2);

[0057] in, The distance between the two mirrors. The intensity transfer coefficient between the two mirrors. and The phase introduced by the two mirrors, x, y are the pupil coordinates. The final light intensity on the detector. It can be obtained from the complex light field Self and its conjugate The product is obtained as shown in equation (3):

[0058] (3);

[0059] The wavefront optical field distribution model under a single wavelength is shown in equation (4):

[0060] (4);

[0061] in, The wavefront light field distribution under a single wavelength, For wavelength, The amplitude of a single phase spatial frequency component. The pupil coordinate vector Spatial frequency domain coordinates, For the first Defocus amount per field of view It is the imaginary unit.

[0062] The curvature of the wavefront phase is proportional to the difference in light intensity along the optical axis:

[0063] (5);

[0064] in, The energy distribution before the focal plane, The energy distribution after fozing, For the initial phase, To determine the curvature of the wavefront phase, Fourier series is used as the basis for regional curvature sensing.

[0065] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0066] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A simulation analysis method for large-aperture, wide-field telescopes based on photon accumulation, characterized in that, Includes the following steps: S1: Photon streams with random incident characteristics are set at different positions of a large-aperture, large-field-of-view telescope; the photon streams are reflected by the reflecting surfaces of each mirror of the large-aperture, large-field-of-view telescope; wherein, the optical surface shape of each mirror is different. S2: Delineate the measurement area on the target surface of the detector of the large-aperture, wide-field telescope, count the photons arriving at the measurement area on the detector target surface to simulate the imaging signal; at the same time, count the photons arriving at the non-measurement area on the detector target surface to simulate background noise. S3: Based on the imaging signal and background noise simulated in step S2, simulate stray light from the off-axis field of view, and determine the signal-to-noise ratio of the large-aperture, large-field telescope based on the simulation results.

2. The simulation analysis method for large-aperture, large-field-of-view telescopes based on photon accumulation according to claim 1, characterized in that, The randomly incident photon stream follows a normal or Poisson distribution.

3. The simulation analysis method for large-aperture, large-field-of-view telescopes based on photon accumulation according to claim 1, characterized in that, Before step S1, the following steps are also included: An analytical model for multi-mirror correction is constructed based on standard spherical wave and Fourier optics theory.

4. The simulation analysis method for large-aperture, large-field-of-view telescopes based on photon accumulation according to claim 3, characterized in that, The establishment of the analytical model specifically includes: The light source is described using the complex amplitude expression of a spherical wave under the paraxial approximation. According to Fresnel diffraction law, calculate the complex amplitude distribution of the light field after it has been modulated by at least two mirrors; The final light intensity distribution on the detector is obtained by multiplying the complex amplitude distribution with its conjugate.

5. The simulation analysis method for large-aperture, large-field-of-view telescopes based on photon accumulation according to claim 3 or 4, characterized in that, The analytical model adopts the following wavefront optical field distribution model under a single wavelength: ； in, The wavefront light field distribution under a single wavelength, For wavelength, The amplitude of a single phase spatial frequency component. The pupil coordinate vector Spatial frequency domain coordinates, For the first Defocus amount per field of view, It is the imaginary unit.

6. The simulation analysis method for large-aperture, large-field-of-view telescopes based on photon accumulation according to claim 5, characterized in that, The curvature of the wavefront phase is proportional to the difference in light intensity along the optical axis: ； in, The energy distribution before the focal plane, The energy distribution after fozing, For the initial phase, The curvature of the wavefront phase.

7. The simulation analysis method for large-aperture, large-field-of-view telescopes based on photon accumulation according to claim 1, characterized in that, Large-aperture, wide-field-of-view telescopes consist of a primary mirror, secondary mirrors, and a third mirror. The primary mirror is composed of multiple sub-mirrors, with at least one sub-mirror having its edge tilted.

8. The simulation analysis method for large-aperture, large-field-of-view telescopes based on photon accumulation according to claim 7, characterized in that, An optical fiber is connected between the three mirrors and the detector. The order of the mode field is determined based on the numerical aperture of the optical fiber. The beam distribution within the optical fiber is fitted based on the mode field and the substrate to simulate the order of the mode field within the optical fiber.

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