| 其他摘要 | Laser ranging is a technology with high measurement accuracy in the range measurements of space targets at present. The measured data has very important scientific research and application value. The 1.2m telescope of Yunnan Observatories has carried out laser ranging research and test for many years, and now has the ability to carry out laser ranging for space targets such as satellites, space debris and lunar reflectors. Using the 1.2m telescope laser ranging system, the research team measured the distance of space debris with a 36cm diameter in 2017, and the distance of the lunar retroreflector in early 2018, which shows that the system has good detection capability. In order to further develop the detection capability of the 1.2m telescope ranging system, this paper studies a new method to improve the echo rate of the ranging system. The main work is as follows: First, according to the current situation and existing problems of the ranging technology of 1.2m telescope, a method to improve the echo rate of the ranging system is proposed, that is, the quick response and high resolution FSM are used to ensure the high-precision tracking and aiming of space targets, so as to improve the echo rate of the ranging system. Although the 1.2m telescope ranging system has good detection performance, there are still some details to be solved. After further improving the echo rate, the system will have the laser ranging capability for deep space cooperative targets and smaller, more distant non cooperative targets. Secondly, the factors that affect the echo rate in laser ranging are analyzed, including velocity aberration, telescope tracking error, atmospheric turbulence and telescope pointing error.And the relationship between velocity aberration and target orbital height is obtained. The maximum velocity aberration of space target decreases with the increase of orbital height.The maximum velocity aberration of the LEO target is about 10 ", while the maximum velocity aberration of the lunar reflector is only 1.4". The small deviation of the space target can be corrected by FSM. Thirdly, the FSM is applied to the transmission optical path of 1.2m telescope, and the FSM is used to control the laser beam direction with high resolution and high precision, so as to improve the success rate of laser ranging and the number of returned photons. (1) Analyzing the the position of FSM in transmitting optical path; (2)The resolution of the system with FSM in the transmitting optical path is tested and the effect of FSM in transmitting optical path is simulated;(3)The experiment is carried out for the FSM open-loop control by observing satellites. The experimental results show that the FSM can find the position with stronger echo by searching in laser ranging, and the farther the target is, the more obvious the effect is. Fourthly, a new FSM control algorithm is proposed, which uses the echo photon number as the feedback value of the FSM closed-loop control, and achieves good control effect. The closed-loop control system of the FSM is designed, and the closed-loop control tests are carried out for satellites with different orbital heights on the basis of the high-precision pointing of the 1.2m telescope. The test results show that the echo rate is improved under different observation conditions after using FSM closed-loop control. Fifthly, the feasibility of applying FSM to the 1.2m telescope laser ranging system is simulated and analyzed. First, the position of the FSM in the receiving optical path is designed; Then, the influence of the diameter of aperture in the receiving optical path on the receiving field view is calculated, and the satellite ranging test is carried out to calculate the distribution of echo signals of different targets in the receiving field view; Finally, the correction ability of FSM at different deviation angles of the echo signal is simulated. To sum up, this paper applies the high-speed and high-resolution FSM to the 1.2m telescope laser ranging system, and improves the system's detection capability by improving the system's ranging echo rate. It has certain reference value for daytime space target laser ranging, lunar laser ranging, and further deep space optical ranging. |
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