Laser micro-propulsion system based on micro-size zoom optical module

Abstract

The invention discloses a laser micro-propulsion system based on a micro-size zoom optical module. The laser micro-propulsion system comprises a laser light source, a working medium supply device, a target belt, a pre-collimating lens, a first beam expanding lens, a second beam expanding lens, a focusing lens and a diaphragm, wherein the target belt is wound on the working medium supply device, and the target belt is positioned at the rear part of the light of the diaphragm; the laser light source emits single-mode pulse laser, the single-mode pulse laser is pre-collimated by the pre-collimating lens to form a pre-collimated light beam, the pre-collimated light beam is expanded and collimated by the first beam expander and the second beam expander in sequence to obtain an expanded and collimated light beam, the expanded and collimated light beam is focused by the focusing lens to obtain a focused light beam, and the focused light beam is focused by the focusing lens to obtain a focused light beam. And the focused light beam is emitted from the diaphragm and acts on the target belt to form a jet plume. The dynamic adjustment of the specific impulse and the thrust of the micro-propulsion system is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of space micro-propulsion systems, and in particular relates to a laser micro-propulsion system based on a micro-size zoom optical module. Background Art

[0002] Micro-nano satellites have the advantages of small size, light weight, low cost, short development cycle, and flexible launch methods. They are widely used in communication, navigation, remote sensing and other fields, and are an important direction of current aerospace development. Due to the limitations of the micro-nano satellite's own payload capacity, conventional thrusters are difficult to meet the requirements of small satellite attitude and orbit control functions. Phipps of the United States first proposed a laser micro-propulsion solution for micro-nano satellites. Laser micro-propulsion technology uses lasers as energy sources, focuses the laser on the surface of the ablated material, and forms a tiny material jet to generate thrust. Laser micro-propulsion technology has the characteristics of small and controllable thrust and high specific impulse. This technology is an effective way to solve the flexible operation of micro-nano satellites in orbit.

[0003] At present, laser micro-thrusters mainly adjust thrust by changing laser power. However, the laser power adjustment range generally does not exceed one order of magnitude, and the thrust adjustment range is limited. In addition, the single laser pulse width characteristic leads to a fixed thruster working mode, and it is impossible to flexibly switch between low specific impulse and high thrust mode and high specific impulse and low thrust mode. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, to provide a laser micro-propulsion system based on a micro-size zoom optical module, and to achieve dynamic regulation of the specific impulse and thrust of the micro-propulsion system.

[0005] The objective of the present invention is achieved through the following technical solutions: A laser micro-propulsion system based on a micro-size zoom optical module, comprising: a laser light source, a working fluid supply device, a target belt, a pre-collimation mirror, a first beam expander, a second beam expander, a focusing mirror and a window; wherein the target belt is wound on the working fluid supply device, and the target belt is located at the rear of the light of the window; the laser light source emits a single-mode pulse laser, which is pre-collimated by the pre-collimation mirror to form a pre-collimated light beam, the pre-collimated light beam is expanded and collimated by the first beam expander and the second beam expander in sequence to obtain an expanded collimated light beam, the expanded collimated light beam is focused by the focusing mirror to obtain a focused light beam, the focused light beam is emitted from the window and acts on the target belt to form a jet plume.

[0006] In the above-mentioned laser micro-propulsion system based on a micro-size zoom optical module, the laser light source is a single-mode pulse fiber laser; the laser light source switches the pulse width by direct current modulation to achieve millisecond pulse width output and nanosecond pulse width output.

[0007] In the above-mentioned laser micro-propulsion system based on a micro-size zoom optical module, the pre-collimation mirror is a plano-convex lens, the first beam expander is a biconcave lens, the second beam expander is a biconvex lens, the focusing mirror is a biconvex lens, and the window piece is flat glass.

[0008] In the above-mentioned laser micro-propulsion system based on a micro-size zoom optical module, the pre-collimation mirror, the first beam expander, the second beam expander, the focusing mirror and the window plate are all on the same optical axis.

[0009] In the above-mentioned laser micro-propulsion system based on a micro-size zoom optical module, the pre-collimation mirror, the first beam expander, the second beam expander, the focusing mirror and the window piece are all made of fused quartz.

[0010] In the above-mentioned laser micro-propulsion system based on a micro-size zoom optical module, the target belt is a double-layer structure, wherein the substrate of the target belt is a transparent constrained film material, and the energetic polymer is uniformly coated on the substrate surface as an ablative working fluid.

[0011] In the above-mentioned laser micro-propulsion system based on the micro-size zoom optical module, the position of the first beam expander is changed in the direction of the optical axis to adjust the size of the focused light spot on the target zone.

[0012] In the above-mentioned laser micro-propulsion system based on the micro-size zoom optical module, the diameter of the focused light spot is 50 μm to 2 mm.

[0013] In the above-mentioned laser micro-propulsion system based on the micro-size zoom optical module, the laser center wavelength of the laser light source is 1 μm, the average power is 50 W, the pulse width range is 10 ns to 1 ms, and the repetition rate is 100 Hz.

[0014] In the above-mentioned laser micro-propulsion system based on the micro-size zoom optical module, the focal length of the pre-collimator is 8.88mm-8.9mm, and the thickness of the pre-collimator is 2mm-2.2mm; the focal length of the first beam expander is -4.571mm~-4.5mm, and the thickness of the first beam expander is 2mm-2.2mm; the focal length of the second beam expander is 20mm~21mm, and the thickness of the second beam expander is 2.5mm~2.8mm.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The present invention realizes the switching of different working modes of the propulsion system, namely, high specific impulse, low thrust and low specific impulse, high thrust, by adjusting the pulse width of the pulsed laser; the dynamic adjustment of the specific impulse and thrust of the micro-propulsion system is realized by changing the position of the first beam expander in the direction of the optical axis to change the target spot size; the present invention has a clear design principle, and the effect it can achieve breaks through the limitation of the single working mode of the general laser micro-propulsion system, and significantly improves the ability of the propulsion system to be applied in multi-task scenarios;

[0017] (2) The present invention uses pulsed fiber laser as the energy source, which has the advantages of easy integration, high reliability, large single pulse energy, and controllable overall power consumption, and is suitable for small space platform propulsion systems with certain thrust requirements. In addition, the pulse width tunable function can meet the requirements of two working modes: low specific impulse and high thrust, and high specific impulse and low thrust;

[0018] (3) The present invention uses a micro-sized zoom optical module to focus the laser beam, and the laser power density adjustment range is increased by three orders of magnitude, which can greatly increase the thrust range;

[0019] (4) The present invention adopts a transmission-type double-layer target strip structure. The substrate can constrain the splashing direction of the ablative working fluid to obtain higher propulsion efficiency. The transmission mode can effectively reduce the contamination of the plume to the optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0021] Figure 1 is a schematic diagram of a laser micro-propulsion system based on a micro-size zoom optical module provided by an embodiment of the present invention;

[0022] Figure 2 is a three-dimensional schematic diagram of the optical path of an optical module provided by an embodiment of the present invention;

[0023] Figure 3 are different zoom states of the optical module provided by the embodiment of the present invention;

[0024] FIG4( a ) is a simulation diagram of a focusing state with a spot diameter of 50 μm provided by an embodiment of the present invention;

[0025] FIG4( b ) is a simulation diagram of a focusing state with a spot diameter of 1 mm provided by an embodiment of the present invention;

[0026] FIG4( c ) is a simulation diagram of a focusing state with a spot diameter of 2 mm provided by an embodiment of the present invention;

[0027] Figure 5 It is a schematic diagram of the structure of the target belt provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0028] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0029] Figure 1 Schematic diagram of a laser micro-propulsion system based on a micro-sized zoom optical module provided by an embodiment of the present invention. Figure 1 As shown, the laser micro-propulsion system based on the micro-size zoom optical module includes: a laser light source 1, a working fluid supply device 2, a target belt 3, a pre-collimation mirror 4, a first beam expander 5, a second beam expander 6, a focusing mirror 7 and a window 8; wherein the target belt 3 is wound on the working fluid supply device 2, and the target belt 3 is located at the rear of the light of the window 8; the laser light source 1 emits a single-mode pulse laser, which is pre-collimated by the pre-collimation mirror 4 to form a pre-collimated beam, and the pre-collimated beam is expanded and collimated by the first beam expander 5 and the second beam expander 6 in sequence to obtain an expanded collimated beam, and the expanded collimated beam is focused by the focusing mirror 7 to obtain a focused beam, and the focused beam is emitted from the window 8 and acts on the target belt 3 to form a jet plume. The size of the focused spot on the target belt 3 is adjusted by changing the position of the first beam expander 5 in the direction of the optical axis. The diameter of the focused spot is 50μm to 2mm.

[0030] The pulse laser is collimated and focused by the zoom optical system and acts on the transmission target belt. The position of the first beam expander 5 is adjusted in the direction of the optical axis to change the target spot size range (50μm~2mm), and a jet plume is generated to form thrust. By directly modulating the laser pulse width, millisecond pulse / nanosecond pulse laser output can be obtained respectively to meet the needs of different working modes.

[0031] The laser light source 1 is a single-mode pulse fiber laser. The pulse width is switched by direct current modulation, and the laser light source can achieve 1 millisecond pulse width output and nanosecond pulse width output respectively. The pre-collimation mirror 4 in the micro-size zoom optical module pre-collimates the pulse laser beam to form a relatively collimated beam that enters the beam expansion unit. The beam expansion unit is composed of a beam expander 5 and a beam expander 6. The unit further collimates the beam, and the collimation of the laser beam is further improved. The focusing mirror 7 focuses the aligned beam and finally acts on the target belt 3. The position of the beam expander 5 is changed in the direction of the optical axis to adjust the size of the focused spot. The window piece 8 can prevent the splashes generated during the action of the laser and the working fluid from contaminating the optical system. The working fluid supply device 2 and the target belt 3 adopt a transmission magnetic tape structure to provide ablative working fluid for the micro-thrust system.

[0032] Laser source 1 is a pulsed fiber laser with a central wavelength of 1 μm and a beam quality of M 2 <1.1, can realize direct pulse width current modulation, the pulse width tuning range is 10ns~1ms.

[0033] The pre-collimator 4 is a plano-convex lens, the first beam expander 5 is a biconcave lens, the second beam expander 6 is a biconvex lens, the focusing lens 7 is a biconvex lens, and the window 8 is a flat glass. The pre-collimator 4, the first beam expander 5, the second beam expander 6, the focusing lens 7 and the window 8 are all on the same optical axis.

[0034] The pre-collimation lens 4, the first beam expander 5, the second beam expander 6, the focusing lens 7 and the window 8 are all made of fused quartz, which is suitable for high optical power laser systems.

[0035] The working medium supply device 2 conducts the ablative working medium through the reel.

[0036] The target strip 3 is a double-layer structure, wherein the substrate of the target strip 3 is a transparent constrained film material, and the energetic polymer is used as an ablative medium and is evenly coated on the surface of the substrate.

[0037] The medium supply device 2 and the target tape 3 adopt a transmission magnetic tape structure. The medium supply device 2 conducts the ablation medium through a reel. The target tape 3 is a double-layer structure. The substrate is made of a transparent constrained film material. An energetic polymer is selected as the ablation medium and is evenly coated on the surface of the transparent substrate. The thickness of the ablation medium is 50 to 150 μm.

[0038] The laser light source 1 has a laser center wavelength of 1 μm, an average power of 50 W, a pulse width range of 10 ns to 1 ms, and a repetition rate of 100 Hz.

[0039] The focal length of the pre-collimator 4 is 8.896mm-8.9mm, and the thickness of the pre-collimator 4 is 2mm-2.2mm; the focal length of the first beam expander 5 is -4.571mm~4.5mm, and the thickness of the first beam expander 5 is 2mm-2.2mm; the focal length of the second beam expander 6 is 20mm~21mm, and the thickness of the second beam expander 6 is 2.5mm~2.8mm.

[0040] Specifically, in this embodiment, the laser light source 1 is a single-mode pulse fiber laser, and the beam has a Gaussian distribution. 2 The value is 1~1.1, the laser center wavelength is 1μm, the average power is 50W, the pulse width range is 10ns~1ms, and the repetition rate is 100Hz.

[0041] The micro-size zoom optical module in this embodiment includes a pre-collimator 4, a first beam expander 5, a second beam expander 6, a focusing lens 7 and a window 8, and each optical component is on the same optical axis; the laser beam is pre-collimated by the pre-collimator 4 to form a relatively collimated beam that enters the beam expansion unit, which is composed of a beam expander 5 and a beam expander 6. The unit further collimates the beam, and the focusing lens 7 focuses the collimated beam, which finally acts on the target belt through the window 8. The three-dimensional effect of the optical path is as follows: Figure 2 shown.

[0042] In this embodiment, for the convenience of explanation, the surface of the lens facing the laser transmission direction is defined as the front surface, and the opposite is defined as the rear surface.

[0043] In this embodiment, the distance from the laser output end to the working medium target belt does not exceed 50mm, the focal length of the pre-collimator 4 is 8.896mm, and the thickness is 2mm; the focal length of the first beam expander 5 is -4.571mm, and the thickness is 2mm; the focal length of the second beam expander 6 is 20mm, and the thickness is 2.5mm; the distance between the rear surface of the pre-collimator 4 and the front surface of the second beam expander 6 is 15mm, and the position of the beam expander 5 is changed in the direction of the optical axis to adjust the diameter of the target spot to: 50μm~2mm, and the optical path has different zoom states such as Figure 3 As shown; the focal length of the focusing mirror 7 is 20mm and the thickness is 2.5mm; the distance between the rear surface of the beam expander 6 and the front surface of the focusing mirror 7 is 1mm, and the rear intercept is 20mm, which can prevent the window piece 8 from being contaminated by the ablated material.

[0044] When the incident laser waist diameter is 30 μm, the numerical aperture is 0.065, and the beam quality is M 2=1.05, the focusing state simulation diagrams of the first beam expander 5 at different positions are shown in Figures 4(a), 4(b) and 4(c). Figure 4(a) is a state diagram of the focused spot diameter of 50μm when the distance between the rear surface of the pre-collimator 4 and the front surface of the first beam expander 5 is 2.3mm, and the distance between the rear surface of the first beam expander 5 and the front surface of the second beam expander 6 is 11.7mm; Figure 4(b) is a state diagram of the focused spot diameter of 1mm when the distance between the rear surface of the pre-collimator 4 and the front surface of the first beam expander 5 is 6mm, and the distance between the rear surface of the first beam expander 5 and the front surface of the second beam expander 6 is 8mm; Figure 4(c) is a state diagram of the focused spot diameter of 2mm when the distance between the rear surface of the pre-collimator 4 and the front surface of the first beam expander 5 is 11mm, and the distance between the rear surface of the first beam expander 5 and the front surface of the second beam expander 6 is 3mm; It can be seen from the simulation results that the focused spot size of this zoom optical module can cover the range of 50μm to 2mm.

[0045] Figure 5 It is a schematic diagram of the target belt 3 structure. The substrate is a transparent constrained film material with a thickness of 100μm. The ablation layer is an energetic polymer, which is evenly coated on the substrate and has a thickness of 50 to 150μm. The focused laser beam acts on the target belt ablation layer through the window piece 8 to form a jet plume. After each ignition and ablation is completed, the transmission device rotates to replace the ablation surface of the target belt to provide new ablation medium.

[0046] This embodiment has the following characteristics: 1) The single pulse energy of the pulse fiber laser is large, the power consumption is controllable, and the pulse width is tunable, which can meet the two mission requirements of low specific impulse and high thrust and high specific impulse and low thrust; 2) The target spot size can be adjusted, and the laser power density range is 1.6×10 9 ~2.5×10 12 W / cm 2 , greatly improving the thrust range; 3) The double-layer target belt structure can constrain the direction of the plume injection and improve the propulsion efficiency. The transmission laser action mode can effectively avoid the ablation product from contaminating the optical system and increase the service life of the thruster.

[0047] This embodiment achieves the switching of different working modes of the propulsion system, namely, high specific impulse, low thrust and low specific impulse, high thrust, by adjusting the pulse width of the pulsed laser; by changing the position of the first beam expander in the direction of the optical axis to change the target spot size, the dynamic adjustment of the specific impulse and thrust of the micro-propulsion system is achieved; the design principle of this embodiment is clear, and the effect it can achieve breaks through the limitation of the single working mode of the general laser micro-thruster, and significantly improves the ability of the propulsion system to be applied in multi-task scenarios; this embodiment uses a pulsed fiber laser as an energy source, which has the advantages of easy integration, high reliability, large single pulse energy, and controllable overall power consumption, and is suitable for the application of small space platform propulsion systems with certain thrust requirements. In addition, the pulse width tunable function can meet the requirements of two working modes, namely, low specific impulse and high thrust, and high specific impulse and low thrust; this embodiment uses a micro-size zoom optical module to focus the laser beam, and the laser power density adjustment range is increased by three orders of magnitude, which can greatly increase the thrust range; the present invention adopts a transmission double-layer target belt structure, and the substrate can constrain the splashing direction of the ablative working fluid to obtain higher propulsion efficiency, and the transmission mode can effectively reduce the pollution of the plume to the optical system.

[0048] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A laser micro-propulsion system based on a micro-sized zoom optical module, characterized in that include: A laser light source (1), a working fluid supply device (2), a target belt (3), a pre-collimation lens (4), a first beam expander (5), a second beam expander (6), a focusing lens (7) and a window plate (8); wherein: The target belt (3) is wound on the working medium supply device (2), and the target belt (3) is located behind the light of the window plate (8); The laser light source (1) emits a single-mode pulse laser, which is pre-collimated by the pre-collimation mirror (4) to form a pre-collimated light beam, which is expanded and collimated by the first beam expander (5) and the second beam expander (6) in sequence to obtain an expanded collimated light beam, which is focused by the focusing mirror (7) to obtain a focused light beam, which is emitted from the window plate (8) and acts on the target band (3) to form a jet plume.

2. The laser micro-propulsion system based on a micro-size zoom optical module according to claim 1, characterized in that: The laser light source (1) is a single-mode pulse fiber laser; the laser light source (1) switches the pulse width by direct current modulation to achieve millisecond pulse width output and nanosecond pulse width output.

3. The laser micro-propulsion system based on a micro-size zoom optical module according to claim 1, characterized in that: The pre-collimating lens (4) is a plano-convex lens, the first beam expander (5) is a biconcave lens, the second beam expander (6) is a biconvex lens, the focusing lens (7) is a biconvex lens, and the window plate (8) is a flat glass.

4. The laser micro-propulsion system based on a micro-size zoom optical module according to claim 1, characterized in that: The pre-collimating lens (4), the first beam expander (5), the second beam expander (6), the focusing lens (7) and the window plate (8) are all located on the same optical axis.

5. The laser micro-propulsion system based on a micro-size zoom optical module according to claim 1, characterized in that: The pre-collimating lens (4), the first beam expander (5), the second beam expander (6), the focusing lens (7) and the window plate (8) are all made of fused quartz.

6. The laser micro-propulsion system based on a micro-size zoom optical module according to claim 1, characterized in that: The target belt (3) is a double-layer structure, wherein the substrate of the target belt (3) is a transparent constrained thin film material, and the energetic polymer is used as an ablative working medium and is evenly coated on the surface of the substrate.

7. The laser micro-propulsion system based on a micro-size zoom optical module according to claim 1, characterized in that: The size of the focused light spot on the target band (3) is adjusted by changing the position of the first beam expander (5) in the direction of the optical axis.

8. The laser micro-propulsion system based on a micro-size zoom optical module according to claim 1, characterized in that: The diameter of the focused spot is 50μm~2mm.

9. The laser micro-propulsion system based on a micro-size zoom optical module according to claim 1, characterized in that: The laser light source (1) has a laser center wavelength of 1 μm, an average power of 50 W, a pulse width range of 10 ns to 1 ms, and a repetition rate of 100 Hz.

10. The laser micro-propulsion system based on a micro-size zoom optical module according to claim 1, characterized in that: The focal length of the pre-collimation mirror (4) is 8.88 mm-8.9 mm, and the thickness of the pre-collimation mirror (4) is 2 mm-2.2 mm; The focal length of the first beam expander (5) is -4.571 mm to -4.5 mm, and the thickness of the first beam expander (5) is 2 mm to 2.2 mm; The focal length of the second beam expander (6) is 20 mm to 21 mm, and the thickness of the second beam expander (6) is 2.5 mm to 2.8 mm.

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