A high repetition rate polarization coaxial telescope satellite laser ranging device

Abstract

The invention discloses a high repetition frequency polarization coaxial telescope satellite laser ranging device, comprising an echo receiving terminal, a polarization coaxial device, a guide star CCD, a dichroic mirror, a main wave detector, a corner cube prism, a telescope, etc. The guide star CCD monitors a space target, a high repetition frequency linear polarization laser is emitted from the telescope to the detection target via the polarization coaxial device, and the laser echo returned by the target passes through the same telescope and the polarization coaxial device, is orthogonal to the high repetition frequency linear polarization laser, is reflected from the polarization coaxial device, and is received and detected by an echo receiving terminal with single photon sensitivity, thereby realizing the detection of the laser echo, and measuring the system delay through the corner cube prism, thereby obtaining a high-precision target distance from the laser echo and the system delay, achieving the use of the same telescope for high repetition frequency laser emission and echo reception, effectively reducing the system structure size, improving the laser ranging repetition frequency, and promoting the development and application of the laser ranging system.

Description

Technical Field

[0001] The invention belongs to the field of laser ranging, and more specifically, relates to a high repetition frequency polarization coaxial laser ranging device for a satellite laser ranging system. Background Art

[0002] Laser ranging has the advantages of high accuracy and long distance, and is widely used in the position measurement of space targets such as satellites and space debris. Artificial satellites are widely used in communications, scientific surveys and experiments, military defense, meteorology and other fields. The Global Positioning System GPS and my country's Beidou Positioning System have been widely used in people's social activities and lives, profoundly changing people's lifestyles and promoting human development. At the same time, in the process of human exploration of space, more and more artificial satellites and deep space probes are launched into space. In the harsh space environment of high radiation, vacuum and zero gravity, these human-made aircraft often have risks such as position offset and damage, and thus gradually lose their functions. Satellite laser ranging has the advantages of long distance measurement and high ranging accuracy, making it a conventional means of satellite / space debris orbit determination and monitoring, and has been valued by various countries.

[0003] At present, satellite laser ranging systems usually use a method of separating the transmitting telescope from the receiving telescope. The transmitting telescope is responsible for the emission of the laser, and the receiving telescope is responsible for the detection of laser echoes. During the tracking process of the telescope in various directions, due to the influence of temperature, mechanical and other environmental factors on the optical axis of the transmitting laser and the receiving telescope, the parallelism of the transmitting laser at various locations relative to the optical axis of the receiving telescope is inconsistent when the telescope is in different directions, and the transmitting optical path is slightly displaced, that is, the transmitting laser appears to circle in various directions of the telescope, which affects the aiming of the transmitting laser to the satellite / space debris and increases the difficulty of ranging.

[0004] In the coaxial ranging system, the laser emission optical path is the same as the target monitoring optical path, and the optical path passes through the same optical system and structure. The field of view covered by the laser emission is within the telescope monitoring field of view, and the target monitoring falls within the field of view covered by the laser emission, so the target can be quickly aimed. At the same time, since the laser emission and monitoring optical paths and the echo optical paths all pass through the same optical system and structure, the changes in the ambient temperature have the same impact on the monitoring, emission and echo optical paths, which offset each other and enhance the long-term stability of the ranging system. At present, the coaxial ranging process generally adopts the rotating mirror method. Affected by the rotating mirror speed, the measurement repetition frequency is low, the amount of measurement data is small, and it is difficult to achieve high repetition rate measurement with a repetition frequency of more than kHz. Summary of the invention

[0005] The purpose of the present invention is to provide a high repetition rate polarization coaxial telescope satellite laser ranging device, which utilizes polarization lenses, quarter wave plates, single photon detectors, etc. to achieve high repetition rate coaxial telescope ranging of a cooperative target satellite with a corner cone reflector, reduce the influence of ambient temperature changes on the ranging system, enhance the long-term stability of the system, and avoid the influence of environmental factors on the transmitting optical path and the receiving optical path, resulting in the aiming off-target caused by the circling of the transmitting laser.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A high repetition frequency polarization coaxial telescope satellite laser ranging device, comprising an echo receiving terminal, a polarization coaxial device, a guide star CCD, a dichroic mirror, a main wave detector, a corner cube prism, and a telescope; the characteristics are that when the guide star CCD observes a target, linear polarization with high power and high repetition frequency reaches the polarization coaxial device, the linear polarization rotates 90 degrees to become circular polarization light and reaches the dichroic mirror, a small amount of partial light is received by the main wave detector through the dichroic mirror and converted into an electrical signal at the time of laser emission; a large amount of light is reflected by the dichroic mirror and emitted from the telescope to the target, and the laser echo reflected by the target is received by the telescope, After passing through the dichroic mirror, it is reflected by the polarization coaxial device and enters the echo receiving terminal, where it is converted into an echo electrical signal. The laser echo time is recorded, and the distance value between the target and the system is obtained from the difference between the laser echo time and the laser main wave time. After connecting to the ground target corner cube prism, the laser returns originally, passes through the dichroic mirror, is reflected by the polarization coaxial device and enters the echo receiving terminal, and the ground target distance value of the ground target is recorded. The distance value between the target and the system is subtracted from the ground target distance value to obtain the distance between the target and the corner cube prism ground target, thereby realizing high repetition rate polarization coaxial telescope laser ranging of the target.

[0008] Preferably, the dichroic mirror is highly reflective to the high repetition frequency laser wavelength used, and highly transparent to light of other wavelengths.

[0009] Preferably, the guide star CCD is composed of the third convex lens and the CCD. The target light passes through the telescope through the dichroic mirror and is focused by the third convex lens onto the guide star camera CCD to monitor the star image.

[0010] Preferably, the laser echo receiving terminal is composed of the 45° high-reflection mirror, the first convex lens, the second convex lens, the pinhole aperture, the narrow-band filter and the single-photon detector.

[0011] Preferably, the narrowband filter is placed in front of the single-photon detector, the central wavelength of the narrowband filter is consistent with the central wavelength of the high repetition rate laser, and the line width is 0.1-0.5 nm.

[0012] Preferably, the focal length of the first convex lens is three times that of the second convex lens, and the first convex lens and the second convex lens form a 4f system.

[0013] Preferably, the pinhole aperture is placed at the focus of the first convex lens, and the aperture is adjustable from 0.1 mm to 2 mm, so as to filter out most of the laser diffuse light entering the single-photon detector.

[0014] Preferably, the polarization coaxial device is composed of the linear polarizer and the quarter wave plate, the linear polarizer is a 45° polarizer, and the polarization ratio is ≥1000:1.

[0015] Preferably, the polarizer, quarter wave plate, dichroic lens, 45° reflector, transmitting telescope, receiving telescope and detection receiving terminal are coated with a high reflection film or a high transmission film consistent with the laser light band.

[0016] The beneficial effects brought by the technical solution provided by the present invention are:

[0017] (1) The present invention provides a high repetition rate polarization coaxial telescope satellite laser ranging device, which uses polarization to achieve laser emission and laser echo emission and reception at the same telescope. The repetition frequency of the emitted laser pulse is not affected by the polarization mode, thereby achieving high repetition rate laser ranging;

[0018] (2) The present invention realizes high repetition frequency laser emission and reception by the same telescope, reduces the system's bulk, offsets the impact of the environment on the light transmission and reception path, avoids aiming off-target caused by circling the emitted laser, realizes accurate and rapid distance measurement of the target, increases the amount of distance measurement data of the target, and improves the target monitoring capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0020] Figure 1 It is a schematic diagram of a high repetition rate polarization coaxial laser ranging device according to a preferred embodiment of the present invention.

[0021] Figure 2 Yes Figure 1 A high repetition rate polarization coaxial telescope satellite laser ranging device is shown, which realizes the principle diagram of high repetition rate polarization coaxial.

[0022] Figure 3 Yes Figure 1A high repetition rate polarization coaxial telescope satellite laser ranging device is shown, which is connected to a ground target corner cube prism to obtain the distance between the target and the ground target of the corner cube prism.

[0023] In the figure:

[0024] 1-echo receiving terminal, 11-single photon detector, 12-narrowband filter, 13-second convex lens, 14-pinhole aperture, 15-first convex lens, 16-45° high reflective mirror; 2-polarization coaxial, 21-linear polarizer, 22-quarter wave plate, 3-guide star CCD, 32-third convex lens, 31-CCD camera, 4-dichroic mirror, 5-primary wave detector, 6-corner cone prism, 7-telescope. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail so that the functions and features of the present invention can be better understood.

[0026] like Figure 1 The figure shows a high repetition rate polarization coaxial telescope satellite laser ranging device according to an embodiment of the present invention, including a single photon detector 11, a narrow band filter 12, a second convex lens 13, a pinhole aperture 14, a first convex lens 15, a 45° high reflective mirror 16; a linear polarizer 21, a quarter wave plate 22, a third convex lens 32, a CCD camera 31, a dichroic mirror 4, a main wave detector 5, a corner cone prism 6, and a telescope 7. The telescope 7 tracks the target, and the target is imaged on the guide star CCD 31 of the third convex lens 32 to achieve target observation. The high-power and high-repetition-frequency linearly polarized laser passes through the linear polarizer 21, and the linearly polarized light is rotated 90° by the quarter-wave plate 22 to become circularly polarized light and reaches the dichroic mirror 4. A small amount of light passes through the dichroic mirror 4 and is received by the main wave detector 5 to record the laser emission time; most of the light is reflected by the dichroic mirror 4 and emitted from the telescope 7 to the target. The laser echo reflected by the target is received by the telescope 7, and is reflected by the dichroic mirror 4, the quarter-wave plate 22, and the linear polarizer 21 to the 45° high-reflection mirror 16. The laser echo is composed of a 4f beam reduction system composed of the first convex lens 15 and the second convex lens 13. The pinhole aperture 14 filters out stray light, and the laser echo spot becomes smaller. The laser echo passes through the narrow-band filter 12 and the single-photon detector 11, and is converted into an echo electrical signal in the echo receiving terminal to record the laser echo time; the distance value between the target and the system is obtained by the difference between the laser echo time and the laser main wave time.

[0027] Please see again Figure 2 ,for Figure 1The polarization coaxial principle is shown in the figure. Linear polarized light passes through the polarizer TPF, and is rotated 90° by the quarter-wave plate QWP to become circular polarized light, which is emitted from the telescope TS. The returned laser echo passes through the telescope TS and the quarter-wave plate QWP again. At this time, the circular polarized light becomes vertically polarized light and is reflected from the polarizer TPF, thereby realizing the output and reception of the transmitting laser and the receiving laser by the same telescope.

[0028] Please see again Figure 3 ; Connect to the ground target angle cube prism 6, the linearly polarized laser passes through the linear polarizer 21, and the linearly polarized light is rotated 90° by the quarter wave plate 22 to become circularly polarized light and reaches the dichroic mirror 4. A small part of the light passes through the dichroic mirror 4 and is received by the main wave detector 5 to record the laser emission time; most of the light is reflected by the dichroic mirror 4, emitted from the telescope 7 to the ground target angle cube prism 6, and the laser returns to the original path of the angle cube prism 6, passes through the dichroic mirror 4, and passes through the dichroic mirror 4 to form a point on the guide star CCD as Figure 1 At the position point of the target observation, the reflected light passes through the dichroic mirror 4, the quarter-wave plate 22, the polarizer 21, the high-reflection mirror 16, the first convex lens 15, the pinhole aperture 14, the second convex lens 13, and the narrow-band filter 12 to the single-photon detector 11, and the laser echo moment of the corner cube prism 6 of the ground target is recorded to obtain the ground target distance value of the ground target. Figure 1 The distance between the target and the system is subtracted from the ground target distance to obtain the measured distance of the target.

[0029] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A high repetition rate polarization coaxial telescope satellite laser ranging device, comprising an echo receiving terminal (1), a polarization coaxial device (2), a guide star CCD (3), a dichroic mirror (4), a main wave detector (5), a corner cube prism (6), and a telescope (7), characterized in that: According to the satellite forecast, the guide star CCD monitors the satellite target, the laser is emitted to the measurement target through the polarization coaxial device (2), the dichroic mirror (4), and the telescope (7), and the laser echo is transmitted to the echo receiving terminal through the telescope (7) and the polarization coaxial device (2), so as to realize the reception of the echo; the corner cube prism (6) performs delay measurement on the device, so as to obtain the high-precision target distance from the laser echo and the system delay; The polarization coaxial device (2) is composed of a linear polarizer (21) and a quarter wave plate (22); the linear polarizer (21) is a 45° polarizer; and the linear polarizer (21) and the quarter wave plate (22) have a light aperture of 10 to 40 mm.

2. The high repetition rate polarization coaxial telescope satellite laser ranging device according to claim 1, characterized in that: The echo receiving terminal (1) is composed of a 45° high-reflection mirror (16), a first convex lens (15), a second convex lens (13), a pinhole aperture (14), a narrow-band filter (12) and a single-photon detector (11), wherein the focal length of the first convex lens (15) is three times that of the second convex lens (13).

3. The high repetition rate polarization coaxial telescope satellite laser ranging device according to claim 2, characterized in that: The pinhole aperture (14) is placed at the focus of the first convex lens (15), and the aperture is adjustable from 0.1 mm to 1 mm.

4. The high repetition rate polarization coaxial telescope satellite laser ranging device according to claim 2, characterized in that: The narrowband filter (12) is placed in front of the single-photon detector (11); the central wavelength of the narrowband filter is consistent with the central wavelength of the high repetition frequency laser, and the line width is 0.1-0.5 nm.

5. The high repetition rate polarization coaxial telescope satellite laser ranging device according to claim 1, characterized in that: The dichroic mirror (4) has high transmittance to light of laser wavelength and other wavelengths.

6. The high repetition rate polarization coaxial telescope satellite laser ranging device according to claim 1, characterized in that: The echo receiving terminal (1), the polarization coaxial device (2), the dichroic mirror (4), the corner cube prism (6), and the telescope (7) are coated with a high-reflection film or a high-transmittance film consistent with the laser wavelength.

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