Sub-aperture stitching spectral calibration detection device and detection method thereof

Abstract

The application provides a kind of sub-aperture mosaic spectral calibration detection device and its detection method, wherein the detection device includes: broadband light source, wavelength division multiplexing device, coupler, integrating sphere and spectrometer;Detection device is used to detect large aperture telescope system, and telescope system includes primary mirror and secondary mirror;Broadband light source is used to emit broadband light beam to wavelength division multiplexing device, and wavelength division multiplexing device is used to select the frequency band of broadband light beam, and the incident light beam is transmitted to the pupil of telescope system through coupler, and is incident to focal plane after being reflected twice in primary mirror and secondary mirror of telescope system, and integrating sphere is arranged at the focal plane of telescope system, and the outgoing light beam is transmitted to spectrometer by multimode optical fiber to obtain the actual measured spectral data T (i). The application selects spectrum by wavelength division multiplexing device, and the response generated by different spectrum, finally realizes the splicing detection of system through the cooperation of three domains of space domain, time domain and frequency domain.

Description

Technical Field

[0001] This invention relates to the field of spectroscopy, and in particular to a sub-aperture splicing spectral calibration and detection device and its detection method. Background Technology

[0002] Currently, astronomical observations are developing towards multi-messenger, multi-platform approaches. To achieve higher spatial resolution and ultimate detection capabilities, telescopes will possess higher sensitivity, higher spatial, temporal, and spectral resolution, stronger light-gathering ability, and larger fields of view. Future ground-based telescopes will be in the 30-40 meter range, while space telescopes are expanding from the 6-meter class to the 10-meter class. The James Webb Space Telescope, launched in 2021, has already achieved its first light. Compared to the Hubble Space Telescope, it has a larger aperture, more powerful terminal detectors, and covers the mid-infrared spectral band, enabling it to detect the first light of the early universe. Furthermore, it explores dark matter and dark energy through gravitational lensing and explores habitable exoplanets through fine spectral analysis (during transits with host stars).

[0003] The 3.5-meter Herschel Space Observatory (HSE) can better understand the characteristics of the early universe by detecting infrared light. Furthermore, because infrared light has some penetrating power through interstellar dust, it can observe astronomical phenomena such as galaxy assembly within galactic dust. To achieve high imaging quality and maximize its detection capabilities, the HSE employs discrete phase sub-apertures for integrated detection, ultimately achieving a detection accuracy of 400 nm (λ = 80 μm).

[0004] The LAMOST survey, currently the world's largest spectroscopic survey, has entered the medium-resolution survey stage (R=7500). By acquiring massive amounts of information on celestial physical parameters and chemical abundances, and integrating this information with existing digital survey projects to construct multi-dimensional data, it further promotes the development of temporal astronomy and astronomical big data. For large-aperture, wide-field-of-view systems, off-axis aberrations increase rapidly with the misalignment of telescope optical elements. This, combined with the inherent stiffness limitations of the large-aperture system, ultimately renders observations impossible. Therefore, active attitude control of optical elements and terminals is necessary. Wavefront sensing systems, as the feedback sensing pathway for active optics systems, are fundamental to achieving refined astronomical observations.

[0005] The construction of these large-aperture telescopes not only extends humanity's understanding of the universe to the initial dark ages, enabling the observation of "first light," but also, the combination of large apertures and adaptive optics allows for more detailed observations of the cosmic structure, which is of great significance for understanding important astronomical topics such as black holes, dark matter and dark energy, and Earth-like planets. During the overall assembly and adjustment of the telescopes, as well as the overall wavefront quality testing of the system, wavefront detection is necessary. Current technology uses plane mirrors for self-collimation and collimators to emit plane wavefronts. However, as telescope apertures gradually increase, the cost and technical risks of constructing matching large-aperture plane mirrors and collimators increase rapidly with the increase in aperture. Summary of the Invention

[0006] In view of the above problems, the purpose of this invention is to propose a sub-aperture splicing spectral calibration and detection device and its detection method, which can realize the detection and adjustment of large-aperture telescope optical systems at a lower cost, reduce the dependence on large-aperture collimators, and the separate small-aperture system is less affected by the atmosphere, reducing the volume of the integrating sphere and further improving the detection accuracy.

[0007] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0008] This invention provides a sub-aperture splicing spectral calibration and detection device, comprising: a broadband light source, a wavelength division multiplexing device, a coupler, an integrating sphere, and a spectrometer;

[0009] The detection device is used to detect a large-aperture telescope system, which includes a primary mirror and a secondary mirror.

[0010] The broadband light source is used to emit a broadband beam to the wavelength division multiplexing device. The wavelength division multiplexing device is used to select the frequency band of the broadband beam and transmit the incident beam to the pupil of the telescope system through the coupler. After being reflected twice by the primary mirror and the secondary mirror in the telescope system, the beam is incident on the focal plane. An integrating sphere is set at the focal plane of the telescope system. The outgoing beam is transmitted to the spectrometer by a multimode fiber to obtain the actual measured spectral data T(i).

[0011] Preferably, a scanning pentaprism is provided at the exit position of the coupler, and the detection of different positions of the large-aperture telescope system can be achieved by moving the scanning pentaprism.

[0012] Preferably, the corrected spectral data T0(i) is obtained by correcting the spectral data T(i) obtained from the actual measurement. The calculation process includes:

[0013]

[0014] Where α(i) is the i-th single wavelength λ i Spectral gain, i = 1, 2, ..., N, I(λ) i I0(λ) represents the light intensity measured by the spectrometer. i The intensity of the incident beam is denoted as .

[0015]

[0016] Wherein, G(i) is the total spectral gain of multiple wavelengths at the same location in the telescope system;

[0017]

[0018] in, This represents the average gain of the telescope system at different locations.

[0019]

[0020] Where T(i) is the spectral data obtained from actual measurement, and T0(i) is the corrected spectral data.

[0021] This invention also provides a sub-aperture splicing spectral calibration and detection method, comprising the following steps:

[0022] S1. A broadband light source emits a broadband beam to a wavelength division multiplexing device, wherein the wavelength division multiplexing device selects the frequency band of the broadband beam;

[0023] S2. After frequency band selection, the incident beam is obtained. The incident beam is transmitted to the pupil of the telescope system through the coupler, and after two reflections by the primary mirror and secondary mirror in the telescope system, it is incident on the focal plane to obtain the outgoing beam.

[0024] S3. The emitted beam is transmitted to the spectrometer through the integrating sphere and multimode fiber to obtain the actual measured spectral data T(i);

[0025] S4. By correcting the spectral data T(i) obtained from the actual measurement, the corrected spectral data T0(i) is obtained.

[0026] Preferably, the sub-aperture splicing spectral calibration and detection method according to claim 4 is characterized in that step S4 includes:

[0027]

[0028] Where α(i) is the i-th single wavelength λ i Spectral gain, i = 1, 2, ..., N, I(λ) i I0(λ) represents the light intensity measured by the spectrometer. i The intensity of the incident beam is denoted as .

[0029]

[0030] Wherein, G(i) is the total spectral gain of multiple wavelengths at the same location in the telescope system;

[0031]

[0032] in, This represents the average gain of the telescope system at different locations.

[0033]

[0034] Where T(i) is the spectral data obtained from actual measurement, and T0(i) is the corrected spectral data.

[0035] Compared to existing technologies, this invention uses wavelength division multiplexing (WDM) devices for spectral selection and analyzes the responses generated by different spectra. The final response functions are then stitched together at different frequencies, ultimately achieving system stitching detection through the coordinated operation of the spatial, temporal, and frequency domains. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the sub-aperture splicing spectral calibration and detection device provided in an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram illustrating the relationship between different incident wavelengths and optical fiber modes according to an embodiment of the present invention.

[0038] Figure 3 This is a schematic flowchart of the sub-aperture splicing spectral calibration and detection method provided in an embodiment of the present invention.

[0039] The accompanying reference numerals include: broadband light source 1, wavelength division multiplexing device 2, coupler 3, telescope system 4, primary mirror 41, secondary mirror 42, integrating sphere 5, and spectrometer 6. Detailed Implementation

[0040] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0041] 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.

[0042] Figure 1The structure of the sub-aperture splicing spectral calibration and detection device provided according to an embodiment of the present invention is shown.

[0043] like Figure 1 As shown, the sub-aperture splicing spectral calibration and detection device provided in this embodiment of the invention includes: a broadband light source 1, a wavelength division multiplexing device 2, a coupler 3, a telescope system 4, a primary mirror 41, a secondary mirror 42, an integrating sphere 5, and a spectrometer 6.

[0044] A broadband light source 1 is used to emit a broadband beam to a wavelength division multiplexing device 2. The wavelength division multiplexing device 2 is used to select the frequency band of the broadband beam and transmit the incident beam to the pupil of the telescope system 4 through a coupler. After two reflections by the primary mirror 41 and the secondary mirror 42 in the telescope system 4, the beam finally enters the focal plane. An integrating sphere 5 is set at the focal plane of the telescope system 4. The outgoing beam is transmitted to the spectrometer 6 by a multimode fiber to obtain the actual measured spectral data T(i).

[0045] The actual measured spectral data T(i) is corrected to obtain the corrected spectral data T0(i). The calculation process includes:

[0046]

[0047] Where α(i) is the i-th single wavelength λ i Spectral gain, i = 1, 2, ..., N, I(λ) i I0(λ) represents the light intensity measured by the spectrometer. i ) represents the intensity of the incident beam.

[0048]

[0049] Where G(i) is the total spectral gain of multiple wavelengths at the same position of a large-aperture telescope.

[0050]

[0051] in, This represents the average gain of a large-aperture telescope at different locations.

[0052]

[0053] Where T(i) is the spectral data obtained from actual measurement, and T0(i) is the corrected spectral data.

[0054] In one embodiment of the present invention, a scanning pentaprism is provided at the exit position of the coupler 3. Addressing the shortcomings of traditional free-space propagation scanning pentaprism optical paths, which are greatly affected by atmospheric and environmental vibrations and cannot directly test wavefront errors, this invention utilizes an optical fiber interconnect architecture to achieve waveguide-based photon collection and sensing. Since the optical path of the optical fiber interconnect system is not limited by mechanical structure and space, the surface quality and stiffness requirements of the back-end mechanism can be correspondingly reduced. This allows for the detection and adjustment of large-aperture telescope optical systems at a lower cost, reducing reliance on large-aperture collimators. Furthermore, the split-and-joint small-aperture spectral calibration and detection system provided by this invention is less affected by atmospheric conditions, thus improving detection accuracy.

[0055] Figure 2 The relationship between different incident wavelengths and fiber-type modes provided by embodiments of the present invention is illustrated.

[0056] As shown in the figure, when the incident light is 1560 nm, the obtained mode is the fundamental mode, and the coupling efficiency is the highest at this time, which means the corresponding spectral energy is the strongest.

[0057] This invention addresses confocal imaging, utilizing the differential principle to scan and measure wavefront positions at relatively close distances. Essentially, it measures the change in distance between different mirrors. Because large-aperture telescopes have high wavefront quality, a geometric phase element is used to achieve longer axial dispersion during the confocal process. Furthermore, analysis is performed on different modes of different wavelengths within the optical fiber. Ultimately, it is found that light with a wavelength of 1560 nm primarily exists as a base layer in multimode optical fibers, and its incident energy is higher.

[0058] Its highest energy input point can be obtained through defocusing tests at the incident end. Based on the geometric phase relationship design and the 10mm axial measurement zone containing a 200nm bandwidth, a spectral resolution of 0.1nm is achieved, corresponding to a spatial accuracy of 5µm. For a specific wavelength, both intensity and mode are optimal when the incident angle is optimal.

[0059] Figure 3 The flowchart of the sub-aperture splicing spectral calibration and detection method provided according to an embodiment of the present invention is shown.

[0060] like Figure 3 As shown, the present invention also includes a sub-aperture splicing spectral calibration and detection method, comprising the following steps:

[0061] S1. A broadband light source emits a broadband beam to a wavelength division multiplexing device, wherein the wavelength division multiplexing device selects the frequency band of the broadband beam.

[0062] S2. After frequency band selection, the incident beam is obtained. The incident beam is transmitted to the pupil of the telescope system through the coupler, and after two reflections by the primary mirror and secondary mirror in the telescope system, it is incident on the focal plane to obtain the outgoing beam.

[0063] S3. The emitted beam is transmitted to the spectrometer through the integrating sphere and multimode fiber to obtain the actual measured spectral data T(i).

[0064] S4. By correcting the spectral data T(i) obtained from the actual measurement, the corrected spectral data T0(i) is obtained.

[0065] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0066] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A sub-aperture stitched spectral calibration detection device, comprising: include: Broadband light sources, wavelength division multiplexing devices, couplers, integrating spheres, and spectrometers; The detection device is used to detect a large-aperture telescope system, which includes a primary mirror and a secondary mirror. The broadband light source is used to emit a broadband beam to the wavelength division multiplexing (WDM) device. The WDM device is used to select the frequency band of the broadband beam and transmit the incident beam to the pupil of the telescope system through the coupler. After being reflected twice by the primary and secondary mirrors in the telescope system, the beam is incident on the focal plane. An integrating sphere is set at the focal plane of the telescope system. The outgoing beam is transmitted to the spectrometer via a multimode fiber to obtain the actual measured spectral data. T ( i ).

2. The sub-aperture stitching spectral calibration detection device of claim 1, wherein, A scanning pentaprism is provided at the exit position of the coupler, and by moving the scanning pentaprism, detection can be achieved at different positions of the large-aperture telescope system.

3. The sub-aperture stitching spectral calibration detection apparatus of claim 2, wherein, by correcting the actual measured spectral data T ( i ) obtained by the actual measurement, to obtain corrected spectral data T 0( i ), calculation process include: wherein, α i is the first i single wavelength λ i of the spectral gain, i = 1, 2, …, N, I λ i is the light intensity measured by the spectrometer, I 0 λ i is the light intensity of the incident light beam;​​ Among them, G( i () represents the total spectral gain across multiple wavelengths at the same location on the telescope system; wherein is the average gain for the different positions of the telescope system; wherein T ( i ) is the actually measured spectral data, T 0( i ) is the corrected spectral data.

4. A sub-aperture stitching spectral calibration detection method, characterized in that, Includes the following steps: S1. A broadband light source emits a broadband beam to a wavelength division multiplexing device, wherein the wavelength division multiplexing device selects the frequency band of the broadband beam; S2. After frequency band selection, the incident beam is obtained. The incident beam is transmitted to the pupil of the telescope system through the coupler, and after two reflections by the primary mirror and secondary mirror in the telescope system, it is incident on the focal plane to obtain the outgoing beam. S3, the above exiting light beam is transmitted to the spectrometer through the integrating sphere and the multimode optical fiber to obtain the actually measured spectral data T ( i ) S4, the actual measured spectral data are corrected by T i T i ​​​​ 5. The method of claim 4, wherein, Step S4 includes: in, α ( i ) is the first i A single wavelength λ i Spectral gain, i =1, 2, ..., N, I ( λ i The light intensity is measured by the spectrometer. I 0( λ i The intensity of the incident beam is denoted as . where G(λ) is the total spectral gain of the telescope system at the same position; and i G(λ) = G(λ0) + G'(λ0)(λ - λ0) wherein is the average gain for the different positions of the telescope system; wherein T ( i ) is the actually measured spectral data, T 0( i ) is the corrected spectral data.

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