Static orbit hyper-spectrum detection system applied to high-aging dirt and carbon collaborative observation

Abstract

The invention discloses a stationary orbit hyper-spectrum detection system applied to high-aging dirt and carbon collaborative observation. According to the method, the problem of performance optimization caused by insufficient observation gas component elements, low spatial resolution, low observation timeliness and system integration of an existing remote sensor is solved. The invention provides a stationary orbit hyper-spectrum detection system for cooperative observation of pollution and carbon, which integrates pollution gas and greenhouse gas detection spectrum sections while exerting the advantage of high-time-efficiency observation of a stationary orbit, and realizes large dynamic range, ultra-high spectral resolution and high-sensitivity detection capability of near ultraviolet to short wave infrared atmospheric absorption spectrum.

Description

Technical Field

[0001] This invention relates to the technical field of optical remote sensing, and in particular to a geostationary orbit hyperspectral detection system for high-time-efficiency co-observation of pollution and carbon. Background Technology

[0002] Comprehensive detection methods for pollutants and greenhouse gases can be used to study and differentiate between anthropogenic and natural carbon emission sources, revealing the synergistic patterns between pollution and carbon emissions. This is of great significance for serving my country's "dual carbon" goals and the coordinated governance of environmental pollution. Satellite remote sensing is characterized by objectivity, spatial continuity, and efficient coverage. Employing spaceborne hyperspectral detection methods, and utilizing atmospheric absorption spectra, quantitative information on gas concentrations can be further obtained, thus providing scientific data support for pollution reduction and carbon reduction policies.

[0003] However, low-Earth orbit (LEO) satellites employ ultra-wide swath designs, enabling 24-hour updates of atmospheric composition data, which is insufficient to meet the hourly observation frequency requirements and thus lacks the capability to monitor gas emission processes. Furthermore, their current spatial resolution is only 7 km, limiting their ability to identify the spatial distribution of emission sources. Existing geostationary atmospheric composition remote sensors only have a pollutant gas monitoring spectrum with a spatial resolution of 8 km and lack the capability for simultaneous observation of pollutants and greenhouse gases. The ultraviolet-visible spectral band used for pollutant gas detection is characterized by high solar spectral radiance and intense ozone absorption in certain bands; the energy in this band varies greatly with wavelength, requiring a detection system with high dynamic response capabilities. To address the need for improved spatial resolution in monitoring rapid changes in atmospheric composition and identifying emission sources, a highly integrated geostationary hyperspectral detection system with co-observation capabilities for pollution and carbon emissions is needed. This system would provide real-time monitoring of the complex diurnal cycle of photochemically driven pollutants with high temporal and spatial resolution, and observe the emission and diffusion processes of sudden greenhouse gas events. Summary of the Invention

[0004] This invention provides a geostationary orbit hyperspectral detection system for high-time-efficiency co-observation of pollution and carbon, aiming to overcome the limitations of existing remote sensors in terms of insufficient gas composition elements, low spatial resolution and observation timeliness, as well as performance optimization problems caused by system integration. This invention proposes a geostationary orbit hyperspectral detection system for co-observation of pollution and carbon, which, while leveraging the advantages of high-time-efficiency geostationary orbit observation, integrates the detection spectral bands of pollutants and greenhouse gases, achieving a wide dynamic range, ultra-high spectral resolution, and high sensitivity in the near-ultraviolet to short-wave infrared atmospheric absorption spectrum.

[0005] Firstly, a geostationary orbit hyperspectral detection system for high-time-efficiency co-observation of pollution and carbon is provided, comprising: a scanning mirror, a front-mounted telescope system, a spectral dispersive system, a detector, and a signal processing system; the scanning mirror is located at the front end of the optical path, and a mechanism drives the scanning mirror to scan from east to west, introducing reflected sunlight from different locations on the Earth's surface into the geostationary orbit hyperspectral detection system; the front-mounted telescope system images the beam from the scanning mirror onto the slit position of the spectral dispersive system; the spectral dispersive system collimates and disperses the primary image at the slit and images it onto the detector; the detector converts the imaging spectral light signal into an electrical signal, which is then processed by the signal processing system to finally obtain a digital spectral image signal.

[0006] In conjunction with the first aspect, in some implementations of the first aspect, the spectral dispersion system includes a slit, a collimation system, a dichroic element, a dichroic element, an ultraviolet-visible spectral imaging system, a near-infrared spectral imaging system, and a short-wave infrared spectral imaging system; Light from the front telescope system is transmitted to the collimation system through a slit; the light emitted by the collimation system passes through the dichroic element and forms three spectral channels: ultraviolet-visible channel, near-infrared channel, and short-wave infrared channel; The dichroic element reflects the ultraviolet-visible channel signal to the ultraviolet-visible spectral imaging system and transmits near-infrared to short-wave infrared signals; the signal transmitted by the dichroic element is then split by the dichroic element. The color separation element reflects the near-infrared channel signal to the near-infrared spectral imaging system and transmits the short-wave infrared channel signal to the short-wave infrared spectral imaging system, thereby achieving the division of the three spectral channels.

[0007] In conjunction with the first aspect, in some implementations of the first aspect, the ultraviolet-visible channel is used as the pollutant gas detection channel, the short-wave infrared channel is used as the greenhouse gas detection channel, and the near-infrared channel is used as the correction information acquisition channel for quantitative inversion of gas concentration.

[0008] In conjunction with the first aspect, in some implementations of the first aspect, the front telescope system adopts an off-axis three-mirror structure, and the mirrors of the front telescope system adopt freeform surfaces; the collimation system adopts an off-axis three-mirror structure, and the mirrors of the collimation system adopt an aspherical design.

[0009] In conjunction with the first aspect, in some implementations of the first aspect, the ultraviolet-visible spectral imaging system employs a transmission grating whose diffraction efficiency varies with wavelength in a trend opposite to the distribution of energy input to the solar spectrum in that spectral band; the imaging lens of the ultraviolet-visible spectral imaging system employs spherical and aspherical surfaces, and spectral curvature and spectral linearity are corrected by prisms.

[0010] In conjunction with the first aspect, in some implementations of the first aspect, the ultraviolet-visible spectral imaging system includes an ultraviolet-visible transmission grating, a prism group, and a converging lens group; the ultraviolet-visible transmission grating disperses the incident parallel light, the subsequent prism group further plays the role of weak dispersion and spectral distortion correction, and then the converging lens group images the dispersed slit image well onto the focal plane.

[0011] In conjunction with the first aspect, in some implementations of the first aspect, the UV-Vis transmission grating groove type is a blazed groove, the blazed wavelength is in the spectral range of 300~320nm, and the grating diffraction efficiency of 310nm wavelength / grating diffraction efficiency of 490nm wavelength = 1.75~2.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, the near-infrared spectral imaging system employs a transmission grating; the imaging lens of the near-infrared spectral imaging system employs spherical and aspherical surfaces, and spectral curvature and spectral linearity are corrected by a prism.

[0013] In conjunction with the first aspect, in some implementations of the first aspect, the short-wave infrared spectral imaging system employs an immersion reflective grating; the imaging lens of the short-wave infrared spectral imaging system employs spherical and aspherical surfaces, and spectral curvature and spectral linearity are corrected by a prism.

[0014] In conjunction with the first aspect, in some implementations of the first aspect, the scanning speed of the scanning mirror is matched with the dwell time of a single ground pixel in the detector and signal processing system to achieve hourly area coverage and perform multi-frame overlay during digital signal processing of spectral images.

[0015] Compared with the prior art, the solution provided by the present invention has at least the following beneficial technical effects: (1) The integrated design of the free-form surface off-axis three-mirror telescope system of the present invention with the ultraviolet-visible, near-infrared and short-wave infrared three-channel grating spectrometer system can meet the requirements of high imaging quality with long focal length in static orbit, improve spatial resolution and spectral sampling rate, and enable the spectral dispersive system to adopt conventional spherical or aspherical surfaces, reducing design difficulty. Thus, the simultaneous detection of pollutant gases and greenhouse gases can be achieved through a single system, solving the problem of insufficient observation of gas composition elements by existing remote sensors. It can be used to study and distinguish between anthropogenic and natural carbon emission sources and reveal the synergistic relationship between pollution emissions and carbon emissions.

[0016] (2) While leveraging the advantages of high-efficiency observation from geostationary orbit and achieving hourly regional coverage, this invention further enhances the spatial resolution and detection sensitivity of the remote sensor by optimizing the performance of the optical system, rationally setting the detector integration time, and superimposing multi-frame data during data processing, thereby improving the ability to identify the spatial distribution of emission sources. Through the design of an ultraviolet-visible transmission grating, the variation of the input solar spectral energy with wavelength in this spectral band is compensated, improving the flatness of the spectral response of the ultraviolet-visible channel and realizing the acquisition of energy over a large dynamic range of atmospheric absorption spectra. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the composition principle of the geostationary orbit hyperspectral detection system for high-time-efficiency co-observation of pollution and carbon.

[0018] Figure 2 This is the optical path diagram of the free-form surface off-axis three-reflector telescope system used in this invention.

[0019] Figure 3 This is a schematic diagram of the spectral dispersive system used in this invention.

[0020] Figure 4 This is the optical path diagram of the ultraviolet-visible spectral imaging system used in this invention.

[0021] Figure 5 This is a diffraction efficiency curve of the ultraviolet-visible transmission grating used in this invention. Detailed Implementation

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

[0023] like Figure 1 As shown, this invention provides a geostationary orbit hyperspectral detection system for high-time-efficiency co-observation of pollution and carbon, comprising: a scanning mirror 1, a front-mounted telescope system 2, a spectral dispersive system 3, a detector 4, and a signal processing system 5. The scanning mirror 1 is located at the front end of the optical path and is driven by a mechanism to scan from east to west, introducing reflected sunlight from different locations on the Earth's surface into the geostationary orbit hyperspectral detection system. The front-mounted telescope system 2 images the light beam from the scanning mirror 1 onto the slit of the spectral dispersive system 3. The spectral dispersive system 3 collimates and disperses the primary image at the slit and images it onto the detector 4. The detector 4 converts the imaging spectral light signal into an electrical signal, which is then processed by the signal processing system 5 to finally obtain a digital spectral image signal.

[0024] The front-mounted telescope system 2 features a wide spectral range and a large field of view, employing an off-axis three-mirror structure. Depending on focal length and image quality requirements, the mirrors of the front-mounted telescope system 2 can be aspherical or freeform. In some embodiments, for cases requiring long focal lengths and high image quality in stationary orbits, and where the focal lengths in the spectral and spatial directions differ significantly, the front-mounted telescope system 2 uses freeform surfaces. This allows the spectral dispersive system 3 to utilize conventional spherical or aspherical surfaces while meeting performance requirements, reducing design complexity. Figure 2 As shown, the front telescope system 2 includes a primary mirror 2-1, a secondary mirror 2-2, and a tertiary mirror 2-3. The primary mirror 2-1, the secondary mirror 2-2, and the tertiary mirror 2-3 all adopt freeform surfaces to achieve different focal lengths in the spectral and spatial directions, thus meeting the high image quality requirements at long focal lengths.

[0025] like Figure 3 As shown, the spectral dispersion system 3 includes a slit 3-1, a collimation system 3-2, a dichroic element 3-3, a dichroic element 3-4, an ultraviolet-visible spectral imaging system 3-5, a near-infrared spectral imaging system 3-6, and a short-wave infrared spectral imaging system 3-7. Light from the front-mounted telescope system 2 is transmitted through the slit 3-1 to the collimation system 3-2. The light emitted by the collimation system 3-2 passes through the dichroic elements 3-3 and 3-4 to form three spectral channels. The dichroic element 3-3 reflects the ultraviolet-visible channel signal to the ultraviolet-visible spectral imaging system 3-5 and transmits the near-infrared to short-wave infrared signals. The signal transmitted by the dichroic element 3-3 is then dispersed by the dichroic element 3-4. The dichroic element 3-4 reflects the near-infrared channel signal to the near-infrared spectral imaging system 3-6 and transmits the short-wave infrared channel signal to the short-wave infrared spectral imaging system 3-7. This achieves the division of the three spectral channels. The ultraviolet-visible channel is used for detecting pollutant gases, the short-wave infrared channel is used for detecting greenhouse gases, and the near-infrared channel is used for obtaining correction information required for quantitative inversion of gas concentration.

[0026] In some embodiments, the collimation system 3-2 adopts an off-axis three-mirror configuration, and the mirrors are aspherical. All three spectral imaging systems employ grating dispersion, and each system includes a grating and an imaging lens group. The ultraviolet-visible and near-infrared spectral imaging systems use transmission gratings to achieve high diffraction efficiency, while the short-wave infrared spectral imaging system uses an immersion-type reflection grating to improve dispersion while reducing the spectrometer size. The imaging lenses are spherical and aspherical, and spectral curvature and linearity are corrected by prisms.

[0027] The UV-Vis spectral imaging system 3-5 employs a transmission grating. Its diffraction efficiency varies with wavelength in a trend opposite to the distribution of energy input from the solar spectrum in that spectral band. This improves the flatness of the UV-Vis channel spectral response, enabling the acquisition of spectral energy over a large dynamic range. The imaging lenses of the UV-Vis spectral imaging system 3-5 utilize both spherical and aspherical surfaces, with prisms used to correct spectral curvature and linearity.

[0028] The near-infrared spectral imaging system 3-6 employs a transmission grating, which has high diffraction efficiency. The imaging lenses of the near-infrared spectral imaging system 3-6 utilize both spherical and aspherical surfaces, with prisms used to correct spectral curvature and linearity.

[0029] The short-wave infrared spectral imaging system 3-7 employs an immersion-type reflective grating, which improves dispersion while reducing the size of the spectrometer. The imaging lenses of the short-wave infrared spectral imaging system 3-7 utilize both spherical and aspherical surfaces, with prisms used to correct spectral curvature and linearity.

[0030] UV-Vis spectral imaging system 3-5 system such as Figure 4 As shown, the system includes a UV-Vis transmission grating 3-8, prisms 3-9 and 3-10, and lenses 3-11, 3-12, 3-13, 3-14, 3-15, and 3-16. The UV-Vis transmission grating 3-8 disperses the incident parallel light, and the prisms (prisms 3-9 and 3-10) further weaken the dispersion and correct spectral distortion. Then, the converging lens group (lenses 3-11, 3-12, 3-13, 3-14, 3-15, and 3-16) effectively images the dispersed slit image onto the focal plane.

[0031] In some embodiments, the 3-8 groove type of the ultraviolet-visible transmission grating is a blazed groove, with the blazed wavelength around 300 nm on the shorter wavelength side of the spectral range, and the grating diffraction efficiency distribution is as follows: Figure 5 As shown, the diffraction efficiency at the near-ultraviolet end is approximately twice that at the visible light end (diffraction efficiency of a grating at 310 nm wavelength / diffraction efficiency of a grating at 490 nm wavelength = 1.75~2). This is opposite to the trend of the input solar spectral energy in this spectral band changing with wavelength, which can improve the flatness of the spectral response of the ultraviolet-visible channel and achieve large dynamic range spectral energy acquisition.

[0032] In some embodiments, the scanning speed of the scanning mirror 1 is matched with the ground single-pixel dwell time of the detector 4 and the signal processing system 5 to achieve hourly area coverage, reduce the single-frame integration time, further improve the dynamic range, and perform multi-frame superposition during spectral image digital signal processing to improve the system's detection sensitivity.

[0033] According to one embodiment of the present invention, a geostationary orbit hyperspectral detection system comprises three spectral channels: 300nm-500nm (ultraviolet-visible channel), 750nm-775nm (near-infrared channel), and 1590-1675nm (short-wave infrared channel). The ultraviolet-visible channel is for detecting pollutant gases, the short-wave infrared channel is for detecting greenhouse gases, and the near-infrared channel is for acquiring correction information required for quantitative inversion of gas concentrations. The spectral resolutions of the three channels are 0.6nm, 0.12nm, and 0.3nm, respectively, with a spectral sampling rate of 3, a field of view of 4°, a nadir pixel resolution of 2.5km, and a side-view resolution of 4km at 40° North latitude. The spatial focal length of the ultraviolet-visible and near-infrared channels is 370.6mm, and the spectral focal length is 702mm; the spatial focal length of the short-wave infrared channel is 456mm, and the spectral focal length is 648mm.

[0034] The scanning mirror 1 has a scanning angular velocity of 3.8° per hour, corresponding to a dwell time of 5.8 seconds for scanning 4km of ground pixels. This scanning speed matches the dwell time of a single ground pixel in the detector and signal processing system. This speed enables observation capabilities covering an area of ​​2500km × 2500km within one hour, leveraging the advantages of geostationary orbit for high-timeliness atmospheric environment change monitoring. The 5.8s dwell time can be subdivided into 16-48 frames. By reducing the integration time of a single frame, the dynamic range is further improved. Multi-frame superposition during spectral image digital signal processing enhances the system's detection sensitivity.

[0035] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims of the present invention.

Claims

1. A geostationary orbit hyperspectral detection system for high-time-efficiency co-observation of pollution and carbon, characterized in that, include: The system consists of a scanning mirror (1), a front-mounted telescope system (2), a spectral splitting system (3), a detector (4), and a signal processing system (5). The scanning mirror (1) is located at the front end of the optical path. The mechanism drives the scanning mirror (1) to scan from east to west, introducing the reflected sunlight from different locations on the Earth's surface into the geostationary orbit hyperspectral detection system. The front-mounted telescope system (2) images the light beam from the scanning mirror (1) onto the slit of the spectral splitting system (3). The spectral splitting system (3) collimates and disperses the primary image at the slit and images it onto the detector (4). The detector (4) converts the imaging spectral light signal into an electrical signal, which is then processed by the signal processing system (5) to finally obtain the digital signal of the spectral image.

2. The geostationary orbit hyperspectral detection system according to claim 1, characterized in that, The spectral splitting system (3) includes a slit (3-1), a collimation system (3-2), a dichroic element (3-3), a dichroic element (3-4), an ultraviolet-visible spectral imaging system (3-5), a near-infrared spectral imaging system (3-6), and a short-wave infrared spectral imaging system (3-7). The light from the front telescope system (2) is transmitted to the collimation system (3-2) through the slit (3-1); the light emitted by the collimation system (3-2) is passed through the dichroic element (3-3) and the dichroic element (3-4) to form three spectral channels: ultraviolet-visible channel, near-infrared channel and short-wave infrared channel; The dichroic element (3-3) reflects the ultraviolet-visible channel signal to the ultraviolet-visible spectral imaging system (3-5) and transmits near-infrared to short-wave infrared signals; the signal transmitted by the dichroic element (3-3) is then split by the dichroic element (3-4); The color separation element (3-4) reflects the near-infrared channel signal to the near-infrared spectral imaging system (3-6) and transmits the short-wave infrared channel signal to the short-wave infrared spectral imaging system (3-7), thereby realizing the division of the three spectral channels.

3. The geostationary orbit hyperspectral detection system according to claim 2, characterized in that, The ultraviolet-visible channel is used for detecting pollutant gases, the short-wave infrared channel is used for detecting greenhouse gases, and the near-infrared channel is used for obtaining correction information for quantitative inversion of gas concentration.

4. The geostationary orbit hyperspectral detection system according to claim 2, characterized in that, The front telescope system (2) adopts an off-axis three-mirror structure, and the mirror of the front telescope system (2) adopts a free-form surface; the collimation system (3-2) adopts an off-axis three-mirror structure, and the mirror of the collimation system (3-2) adopts an aspherical design.

5. The geostationary orbit hyperspectral detection system according to claim 2, characterized in that, The ultraviolet-visible spectral imaging system (3-5) uses a transmission grating, whose diffraction efficiency varies with wavelength in the opposite direction to the distribution of solar spectral energy input in that spectral band; the imaging lens of the ultraviolet-visible spectral imaging system (3-5) uses spherical and aspherical surfaces, and prisms are used to correct spectral curvature and spectral linearity.

6. The geostationary orbit hyperspectral detection system according to claim 5, characterized in that, The ultraviolet-visible spectral imaging system (3-5) includes an ultraviolet-visible transmission grating (3-8), a prism group, and a converging lens group. The ultraviolet-visible transmission grating (3-8) disperses the incident parallel light, and the subsequent prism group further plays the role of weak dispersion and spectral distortion correction. Then, the converging lens group images the dispersed slit image well onto the focal plane.

7. The geostationary orbit hyperspectral detection system according to claim 6, characterized in that, The UV-Vis transmission grating (3-8) has a blazed groove with a blazed wavelength in the spectral range of 300~320nm. The grating diffraction efficiency of 310nm wavelength / grating diffraction efficiency of 490nm wavelength = 1.75~2.

8. The geostationary orbit hyperspectral detection system according to claim 2, characterized in that, The near-infrared spectral imaging system (3-6) uses a transmission grating; the imaging lens of the near-infrared spectral imaging system (3-6) is spherical and aspherical, and the spectral curvature and spectral linearity are corrected by a prism.

9. The geostationary orbit hyperspectral detection system according to claim 2, characterized in that, The shortwave infrared spectral imaging system (3-7) uses an immersion reflective grating; the imaging lens of the shortwave infrared spectral imaging system (3-7) is spherical and aspherical, and the spectral curvature and spectral linearity are corrected by a prism.

10. The geostationary orbit hyperspectral detection system according to claim 1, characterized in that, The scanning speed of the scanning mirror (1) is matched with the dwell time of the ground single pixel of the detector (4) and the signal processing system (5) to achieve hourly area coverage and perform multi-frame superposition during spectral image digital signal processing.

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