Fabry-Perot interferometer for satellite optical system and coupled with telescope

Abstract

The invention relates to a Fabry-Perot interferometer used for a satellite optical system and coupled with a telescope, an elastic support part comprises an elastic supporter, a push rod and a pressing ring, a heat preservation part comprises a mirror chamber, a temperature thermocouple, a heating sheet and a thermal control thermal insulation layer, the mirror chamber surrounds the outer periphery of an optical element, and the temperature thermocouple is arranged in the mirror chamber. The heating sheet surrounds the periphery of the outer side of the mirror chamber, the thermal control thermal insulation layer wraps the heating sheet to play a role in heat preservation and insulation protection, and the base part comprises a soft rubber buffer gasket and a base and is used for supporting and fixing an interferometer. An image received from a satellite telescope passes through a Fabry-Perot interferometer before being transmitted to a focal plane component detector to form an interference pattern of concentric rings, and each interference fringe represents a different wavelength. The invention is a wide-angle Fabry-Perot interferometer having a large aperture, which can maximize the optical throughput and high fineness, thereby providing high spectral resolution, enabling the measurement of precise wavelengths in each pixel of the detector.

Description

Technical Field

[0001] The invention relates to the technical field of optical measurement, in particular to a Fabry-Perot interferometer used in a satellite optical system and coupled to a telescope. Background Art

[0002] With the continuous improvement of environmental awareness, the demand for monitoring harmful gases that may be produced in industrial production processes is also growing. At present, in addition to the use of continuous emission monitoring systems installed on industrial facilities to monitor atmospheric emissions, some large scientific satellites have been developed internationally for monitoring atmospheric trace gases, such as Europe's Envisat and Sentinel-5P, but these satellites still have problems with field of view size and spatial resolution, and cannot guarantee that the satellite will collect enough light in a single pass to measure atmospheric trace gases in different wavelength ranges. Summary of the invention

[0003] In order to solve the above problems existing in the existing atmospheric trace gas monitoring, the present invention proposes a Fabry-Perot interferometer for a satellite optical system and coupled to a telescope, and the interferometer is a wide-angle Fabry-Perot interferometer. The image received from the satellite telescope passes through the Fabry-Perot interferometer before being transmitted to the focal plane component detector, and forms an interference pattern of concentric rings on the focal plane component detector, and each interference fringe represents a different wavelength. The Fabry-Perot interferometer has a large aperture to maximize the light throughput and high fineness, thereby providing high spectral resolution, which enables the precise wavelength in each pixel of the focal plane component detector to be measured.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A Fabry-Perot interferometer for a satellite optical system coupled with a telescope, wherein the satellite optical system comprises a focal plane component detector, an imaging lens group, a Fabry-Perot interferometer, a telescope group, and a light shield, wherein the light emitted by the telescope group sequentially passes through the Fabry-Perot interferometer and the imaging lens group and then enters the focal plane component detector, and the Fabry-Perot interferometer comprises:

[0006] A base, wherein the base is provided with a plurality of first through holes for connecting with the mirror chamber, and the inner side of the base is provided with three supporting bosses evenly distributed around the circumference, each supporting boss supporting the optical element through a soft rubber supporting gasket thereon;

[0007] The optical element adopts a parallel plane cavity for receiving and transmitting light from the telescope group;

[0008] The mirror chamber is surrounded by the outside of the optical element and is used to support and protect the optical element;

[0009] Three temperature measuring thermocouples are evenly arranged on the outer wall of the mirror chamber and are used to detect the temperature of the mirror chamber;

[0010] A heating plate, which is coated on the outside of the mirror chamber and the temperature measuring thermocouple, and is used to cooperate with the temperature measuring thermocouple to heat the mirror chamber so as to keep the optical element at an optimal working temperature;

[0011] A thermal control insulation layer, covering the outside of the heating plate, for providing thermal insulation and insulation protection to the mirror chamber and the optical element;

[0012] A pressing ring, the pressing ring is in the shape of a concentric disk, the outer edge of the disk is provided with three notches that cooperate with the limit plate at the bottom of the fixed end of the elastic supporter, a second through hole for connecting with the mirror chamber is provided between any two notches, and the pressing ring is also provided with a third through hole for the push rod to pass through;

[0013] Three elastic supports with the same structure, each elastic support having a fourth through hole for connecting with the mirror chamber at a fixed end, and a screw installed in the through hole at the free end to contact with the push rod (320);

[0014] Three push rods, each push rod contacts the optical element after passing through the corresponding third through hole, and is used to work with the elastic support to ensure the positional relationship between the reflectors of the optical element.

[0015] The present invention is used for an optical system for detecting atmospheric trace gas emissions at specific target locations by means of an observation platform that flies over these target locations. The present invention enables each pixel in the focal plane assembly detector to collect light of multiple wavelengths within a selected spectral range and form an interference pattern in the form of concentric circles according to different wavelengths. The beneficial effects of the present invention are:

[0016] 1) The Fabry-Perot interferometer of the present invention is a wide-angle interferometer with an extremely narrow bandpass width, which has the advantages of easy adjustment, high resolution and transmittance, and is suitable for large-aperture and near-infrared observations;

[0017] 2) The Fabry-Perot interferometer of the present invention has a larger aperture, can maximize light throughput, and has higher resolution and transmittance, so that the precise wavelength on each pixel in the focal plane component detector can be measured;

[0018] 3) After the light passes through the Fabry-Perot interferometer of the present invention, a concentric interference pattern is formed in the focal plane detector according to different wavelengths, and each pixel in the focal plane detector collects light of multiple wavelengths in the selected spectral range. During a single pass of the satellite over the target area, the emission data of different trace gases in the atmosphere can be collected simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without exceeding the scope of protection required by the present invention.

[0020] Figure 1 This is a three-dimensional structural diagram of the optical system of the satellite payload;

[0021] Figure 2 for Figure 1 a perspective view of the optical system shown;

[0022] Figure 3 3D structure diagram of Fabry-Perot interferometer;

[0023] Figure 4 for Figure 3 A perspective view of a Fabry-Perot interferometer is shown;

[0024] Figure 5 for Figure 3 An exploded view of a Fabry-Perot interferometer is shown;

[0025] Figure 6 is a transmission function diagram of the Fabry-Perot interferometer of the present invention;

[0026] Figure 7 is a graph showing the relationship between the wavelength of the Fabry-Perot interferometer of the present invention and the incident angle at which the maximum transmittance is obtained;

[0027] Figure 8 This is the concentric fringe pattern that may be produced in the wavelength range of 1630nm-1675nm.

[0028] Explanation of the reference numerals: 10, focal plane assembly detector; 20, imaging lens group; 30, Fabry-Perot interferometer; 301, elastic support; 302, push rod; 303, pressure ring; 304, optical element; 305, mirror chamber; 306, temperature measuring thermocouple; 307, heating plate; 308, thermal control insulation layer; 309, soft rubber support gasket; 310, base; 40, filter; 50, telescope group; 60, second lens group; 70, first lens group; 80, light shield. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0030] like Figure 1 and Figure 2 As shown, the satellite optical system includes a focal plane component detector 10, an imaging lens group 20, a Fabry-Perot interferometer 30, a front telescope group 50 and a light shield 80. The light emitted by the telescope group 50 passes through the Fabry-Perot interferometer 30 and the imaging lens group 20 in sequence and then enters the focal plane component detector 10, wherein the front telescope group 50 includes a filter 40 and a second lens group 60 and a first lens group 70. The first lens group 70, the second lens group 60 and the filter 40 are arranged in sequence from the object side to the image side.

[0031] The satellite optical system uses filters 40 to allow multiple adjacent modes in a selected spectral range to enter the focal plane assembly detector 10 through the Fabry-Perot interferometer 30 and the imaging lens assembly 20. Each pixel in the focal plane assembly detector 10 collects light of multiple wavelengths in the selected spectral range. During a single pass of the satellite over the target area, emission data of different trace gases in the atmosphere can be collected.

[0032] This embodiment provides a Fabry-Perot interferometer used in a satellite optical system and coupled to a telescope, such as Figure 3-Figure 5 As shown, the interferometer mainly includes an elastic support part placed on the upper part of the interferometer, an optical element 304, a heat preservation part surrounding the optical element 304, and a base part. Among them, the elastic support part includes three elastic supports 301 with the same structure, three push rods 302 and a pressure ring 303, the heat preservation part includes a mirror chamber 305, three temperature measuring thermocouples 306, a heating plate 307 and a thermal control insulation layer 308, and the base part includes a soft rubber support pad 309 and a base 310.

[0033] Specifically, the pressing ring 303 is in the shape of a concentric disk, and three notches for placing the elastic supporter 301 are opened on its edge. The three notches are evenly distributed on the pressing ring 303, and each notch is used to plug and cooperate with the limit plate at the bottom of the fixed end of the elastic supporter 301, and a second through hole for connecting with the mirror chamber 305 is provided between any two notches. The pressing ring 303 is connected to the mirror chamber 305 through the second through hole and screws. The number of the second through holes can be set according to actual needs. For example, a total of six second through holes are set on the pressing ring 303. The pressing ring 303 is also provided with a third through hole for the push rod 302 to pass through. The number of the third through holes is the same as the number of the push rod 302. The diameter of the second through hole can be larger than the diameter of the third through hole. Further, as Figure 5 As shown, the third through hole is located in the inner circle of the pressing ring 303, the second through hole is located in the outer circle of the pressing ring 303, and the third through hole is closer to the center of the pressing ring 303 than the second through hole.

[0034] The fixed end of each elastic support 301 is provided with a fourth through hole for connecting with the mirror chamber 305, and the fixed end is fixedly connected with the mirror chamber 305 through the notch of the pressure ring 303 and the fourth through hole, for example, by screws, and the through hole at the free end of the elastic support 301 is equipped with a screw, and the screw contacts one end of the push rod 302, and the other end of the push rod 302 contacts the optical element 304, thereby transmitting the preload from the elastic support 301 to the optical element 304, so that the optical element 304 in the Fabry-Perot interferometer 30 is fixed in the correct position to prevent position changes caused by vibration or mechanical disturbance. Further, the shape of the elastic support 301 in this embodiment is arc-shaped, and three arc-shaped elastic supports 301 are staggered on the pressure ring 303.

[0035] Each push rod 302 is only located in the pressure ring 303 . After passing through the corresponding third through hole, the push rod 302 contacts the optical element 304 . The push rod 302 is used to work with the elastic support 301 to ensure the positional relationship between the reflectors of the optical element 304 .

[0036] The optical element 304 uses a parallel plane cavity and is placed in the mirror chamber 305 for receiving and transmitting light from the satellite telescope assembly 50 .

[0037] The mirror chamber 305 surrounds the outer side of the optical element 304 and is used to support and protect the optical element 304 .

[0038] Three temperature measuring thermocouples 306 are respectively placed on the outer wall of the mirror chamber 305 through the mounting grooves to detect the temperature of the mirror chamber 305. Optionally, the three temperature measuring thermocouples 306 are evenly distributed on the outer wall of the mirror chamber 305 to measure the temperature of the mirror chamber 305 more accurately.

[0039] The heating plate 307 is coated on the outside of the mirror chamber 305 and the temperature measuring thermocouple 306, and is used in conjunction with the temperature measuring thermocouple 306 to keep the Fabry-Perot interferometer 30 at an optimal working temperature. Further, for easy disassembly and assembly, the heating plate 307 is formed by splicing two symmetrical semicircular heating plates.

[0040] The thermal control insulation layer 308 is coated on the outside of the heating plate 307 to provide heat preservation and insulation protection for the mirror chamber 305 and the optical element 304 .

[0041] A plurality of first through holes are formed on the base 310, and the base 310 is fixedly connected to the mirror chamber 305 through the first through holes and screws, and the heating plate 307 and the thermal control insulation layer 308 surrounding the mirror chamber 305 are on the base 310. Three support bosses evenly distributed around the circumference are provided on the inner side of the base 310, and a soft rubber support gasket 309 is placed on each support boss, and the support boss supports the optical element 304 through the soft rubber support gasket 309 thereon.

[0042] Further, see Figure 5 Three pairs of fastening bosses are provided at corresponding positions on the inner side of the base 310 and the inner side of the mirror chamber 305, and each pair of fastening bosses is provided with two through holes, so as to facilitate the fixed connection between the base 310 and the mirror chamber 305. The inner surface of each pair of fastening bosses is an arc that matches the edge curvature radius of the optical element 304.

[0043] In order to further explain the solution of the present invention, the relevant description of the interference cavity of the optical part of the Fabry-Perot interferometer 30 in the present invention is given here.

[0044] The Fabry-Perot interferometer 30 can be viewed as a combination of narrow bandpass filters whose central wavelengths are separated by a fixed amount (free spectral range), and each peak in the Fabry-Perot interferometer cavity transfer function is called a mode. In addition, a characteristic of the Fabry-Perot interferometer 30 is the finesse, which is related to the mirror reflectivity and surface quality of the interferometer cavity. The transmission function of the Fabry-Perot interferometer cavity is as follows:

[0045]

[0046] Where R is the mirror reflectivity, θ is the incident angle, d is the mirror spacing, n is the refractive index of the gap medium, λ is the wavelength, and T(λ) is the transmittance of light with a wavelength of λ. The peak value of this function is λ=dncosθ / k, where k is the interference order. If the obtained signal has box-shaped spectral information from λ1 to λ2, its average spectral radiance is α, and after passing through the Fabry-Perot interferometer 30, the output spectral radiance is α×T(λ). The transmission function diagram is as follows Figure 6 As shown, Figure 6The horizontal axis is the wavelength, and the vertical axis is the transmitted light intensity of the unit amplitude incident light, that is, the transmittance of the incident light. The above transmission function formula of the Fabry-Perot interferometer cavity is applicable to the case of an ideal reflector, that is, the absorption loss is zero and the surface is completely smooth and flat. In actual situations, there will be some defects in the mirror surface, and there are also some other ways to explain these defects. The parameters of the above interferometers are arbitrary, but they must meet two criteria: the FWHM (half the width of the peak) of the interferometer must be narrow enough to achieve the expected spectral resolution limit, and the FSR must be wide enough to transmit the required wavelength range.

[0047] The transmission function of the Fabry-Perot interferometer 30 is a function of the optical path length of the light passing through it, and changing the angle of incidence causes a change in the effective mirror spacing. When a collimated beam passes through the interferometer, different points in the field of view will be imaged with different effective spacings. If the filter only allows a single mode to enter, each pixel has a different narrow bandpass filter, and the central wavelength is a function of the radius of the optical axis. This forms a fringe pattern of concentric rings, where each fringe represents a different wavelength.

[0048] The present invention uses a Fabry-Perot interferometer 30 with a focal plane assembly detector to obtain spectral information. Most high-precision Fabry-Perot interferometer cavities are composed of two curved mirrors to form a resonant cavity. Although it is more difficult to achieve a higher precision with a plane mirror than with a curved mirror. However, since imaging can no longer be performed through an interferometer after using a curved mirror, the present invention uses a pair of mutually parallel plane mirrors to form a resonant cavity. In the present invention, the angle at which light enters the Fabry-Perot interferometer 30 changes the resonant frequency of the cavity, which enables the spectral information of the atmosphere to be obtained in the form of a ring on the focal plane assembly detector 10.

[0049] In order to obtain sufficient signal from the image to retrieve spectral information, the transparent aperture of the Fabry-Perot interferometer must be quite large. In addition, the fineness of the Fabry-Perot interferometer is a combination of reflection fineness and surface fineness. The reflection fineness is determined by the reflectivity of the reflector, and the surface fineness is determined by the surface roughness, surface curvature and relative inclination of the two reflective surfaces of the two reflectors. The Fabry-Perot interferometer 30 of the present invention combines high fineness with a large clear aperture, so that high resolution and high transmittance can be achieved.

[0050] In this embodiment, if the entire wavelength range between 1630 nm and 1675 nm is to be measured by the Fabry-Perot interferometer 30, the receiving angle range needs to be between 0° and ±7.8°. Figure 7 As shown. Figure 7 In FIG. 1 , the horizontal axis is the wavelength (nm), and the vertical axis is the incident angle at which the Fabry-Perot interferometer 30 reaches the maximum transmittance at the corresponding interference order.

[0051] Through the wide-angle Fabry-Perot interferometer 30 of the present invention, the absorption lines will appear as a fringe pattern of concentric rings, each ring representing an atmospheric absorption line, such as Figure 8 shown.

[0052] In this embodiment, the working spectrum of the Fabry-Perot interferometer 30 is 1630nm-1675nm. Correspondingly, the acceptance angle of the interferometer ranges from 0° to ±7.8°. In order to obtain sufficient signals, the aperture of the Fabry-Perot interferometer 30 is 20mm. The optical element 304 in the interferometer uses a plane mirror with a reflectivity of 98%, and the reflection fineness of the plane mirror is 155.5. In addition, the expected surface fineness of this solution is 200. Although the above embodiment is only used as an example to illustrate the use of the present invention in a specific spectral range, the present invention can also be used for spectra outside the above range.

[0053] The Fabry-Perot interferometer proposed by the present invention and used in a satellite optical system coupled with a telescope has the following advantages:

[0054] 1) The Fabry-Perot interferometer of the present invention is a wide-angle interferometer with an extremely narrow bandpass width, which has the advantages of easy adjustment, high resolution and transmittance, and is suitable for large-aperture and near-infrared observations;

[0055] 2) The Fabry-Perot interferometer of the present invention has a larger aperture, can maximize light throughput, and has higher resolution and transmittance, so that the precise wavelength on each pixel in the focal plane component detector can be measured;

[0056] 3) After the light passes through the Fabry-Perot interferometer of the present invention, a concentric interference pattern is formed in the focal plane detector according to different wavelengths, and each pixel in the focal plane detector collects light of multiple wavelengths in the selected spectral range. During a single pass of the satellite over the target area, the emission data of different trace gases in the atmosphere can be collected simultaneously.

[0057] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A Fabry-Perot interferometer for a satellite optical system and coupled to a telescope, the satellite optical system comprising a focal plane component detector (10), an imaging lens group (20), a Fabry-Perot interferometer (30), a telescope group (50), and a light shield (80), wherein light emitted by the telescope group (50) sequentially passes through the Fabry-Perot interferometer (30) and the imaging lens group (20) before entering the focal plane component detector (10), characterized in that: The Fabry-Perot interferometer (30) comprises: A base (310), the base (310) being provided with a plurality of first through holes for connecting with the mirror chamber (305), and the inner side of the base (310) being provided with three supporting bosses evenly distributed around the circumference, each supporting boss supporting the optical element (304) via a soft rubber supporting gasket (309) thereon; The optical element (304) is a parallel plane cavity, used for receiving and transmitting light from the telescope assembly (50); The mirror chamber (305) surrounds the outer side of the optical element (304) and is used to support and protect the optical element (304); Three temperature measuring thermocouples (306) are arranged on the outer wall of the mirror chamber (305) and are used to detect the temperature of the mirror chamber (305); A heating plate (307) is coated on the outside of the mirror chamber (305) and the temperature measuring thermocouple (306) and is used to cooperate with the temperature measuring thermocouple (306) to heat the mirror chamber (305) so as to keep the optical element (304) at an optimal working temperature; A thermal control insulation layer (308), covering the outer side of the heating plate (307), and used for providing heat preservation and insulation protection to the mirror chamber (305) and the optical element (304); A pressing ring (303), the pressing ring (303) is in the shape of a concentric circular disk, the outer edge of the circular disk is provided with three notches that cooperate with the limiting plate at the bottom of the fixed end of the elastic support (301), a second through hole for connecting with the mirror chamber (305) is provided between any two notches, and the pressing ring (303) is also provided with a third through hole for the push rod (302) to pass through; Three elastic supports (301) of identical structure, each elastic support (301) having a fourth through hole for connecting to the mirror chamber (305) at a fixed end, and a screw installed in the through hole at a free end for contacting with the push rod (320); Three push rods (302), each push rod (302) contacts the optical element (304) after passing through the corresponding third through hole, and is used to work together with the elastic support (301) to ensure the positional relationship between the reflectors of the optical element (304).

2. The Fabry-Perot interferometer for a satellite optical system and coupled to a telescope according to claim 1, characterized in that: The working spectrum of the Fabry-Perot interferometer (30) is 1630nm-1675nm, the range of the receiving angle is 0°-±7.8°, and the light aperture is 20mm.

3. The Fabry-Perot interferometer for a satellite optical system and coupled to a telescope according to claim 1, characterized in that: The optical element (304) is a plane reflector with a reflectivity of 98% and a reflection fineness of 155.

5.

4. The Fabry-Perot interferometer for a satellite optical system and coupled to a telescope according to claim 1, characterized in that: Each of the elastic supports (301) is arc-shaped, and the third through hole is located in the inner circle of the pressing ring (303), and the second through hole is located in the outer circle of the pressing ring (303).

5. The Fabry-Perot interferometer for a satellite optical system and coupled to a telescope according to claim 1, characterized in that: The heating plate (307) is formed by splicing two semicircular heating plates with symmetrical structures.

6. The Fabry-Perot interferometer for a satellite optical system and coupled to a telescope according to claim 1, characterized in that: Three pairs of fastening bosses are provided at positions corresponding to the inner side of the base (310) and the inner side of the mirror chamber (305), and each pair of the fastening bosses is provided with two through holes.

7. The Fabry-Perot interferometer for a satellite optical system and coupled to a telescope according to claim 6, characterized in that: The inner surface of each pair of the fastening bosses is an arc shape that matches the edge curvature radius of the optical element (304).

8. The Fabry-Perot interferometer for a satellite optical system and coupled to a telescope according to claim 1, characterized in that: The base (310) and the mirror chamber (305), the pressure ring (303) and the mirror chamber (305), and the elastic support (301) and the mirror chamber (305) are all fixedly connected by screws.

9. The Fabry-Perot interferometer for a satellite optical system and coupled to a telescope according to claim 1, characterized in that: The three temperature measuring thermocouples (306) are evenly distributed on the outer wall of the mirror chamber (305).

10. The Fabry-Perot interferometer for a satellite optical system and coupled to a telescope according to claim 1, characterized in that: The telescope group (50) comprises a first lens group (70), a second lens group (60) and a filter (40) which are arranged in sequence from the object side to the image side.

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