大型天文望远镜中星像传输光纤的设计

发布时间：2018-06-30 19:54

本文选题：LAMOST + 多芯光纤　；参考：《哈尔滨工程大学》2016年硕士论文

【摘要】：近年来,天文领域逐渐掀起了大样本光谱巡天的研究热潮,这使得多目标光纤光谱观测成为研究热点。本文主要针对我国的大天区多目标光纤光谱天文望远镜(LAMOSt)所使用的星像传输光纤进行研究。设计了一种新型五芯特种星像传输光纤,使其在满足传统天文光纤功能的同时具有星像对准功能,以提高LAMOST的光谱获取效率。本文的主要工作内容及成果如下:利用光纤模式耦合理论计算了用于光谱传输的主芯和用于辅助对准的导星芯之间的能量串扰。主芯基模和导星芯基模间的能量最大耦合效率为4.6×10-14%。主芯中LP152模和导星芯中LP11模之间的最大能量耦合效率为1.4×10-8%,其它模式间的最大耦合效率更低。两纤芯间的串扰不会对天文观测产生不利影响,满足天文应用要求。根据模式耦合理论计算了五芯特种星像传输光纤的导星芯分别与阶跃折射率和渐变折射率分离光纤连接时的激励情况,得到了激励系数与两光纤间横向偏移量之间的关系曲线。与阶跃折射率光纤进行连接时,激励系数最大可达90.94%。仿真计算了 LAMOST系统光斑落在五芯特种星像传输光纤端面的情况,得到了各芯中基模激励系数与光斑沿径向偏移量之间的关系曲线,证明该光纤在光斑沿径向偏移100～349μm范围内时有偏移反馈信号。利用插管法制备了五芯特种星像传输光纤探头样品,并用He-Ne激光作为光源测试其对准能力,得到各纤芯出射光强灰度值与光斑径向偏移量之间的关系曲线。当五芯特种星像传输光纤探头在光斑径向偏移量在-305～-155μm和105～270μm范围内时,导星芯有偏移反馈信号。在考虑光斑质量的情况下,实验结果与理论计算基本相符。
[Abstract]:In recent years, the astronomical field has gradually raised the research upsurge of large sample spectral survey, which makes multi-target optical fiber spectral observation become a research hotspot. In this paper, the satellite image transmission fiber used in the large sky multitarget optical fiber spectral astronomical telescope (LAMOST) is studied. A novel five-core special satellite image transmission fiber is designed, which not only meets the function of traditional astronomical optical fiber, but also has the function of star image alignment, in order to improve the spectral acquisition efficiency of LAMOST. The main contents and results of this paper are as follows: the energy crosstalk between the main core for spectral transmission and the guide core for auxiliary alignment is calculated by using the optical fiber mode coupling theory. The maximum energy coupling efficiency between the core mode and the core mode is 4.6 脳 10 ~ (-14). The maximum energy coupling efficiency between the LP152 mode in the main core and the LP11 mode in the guide core is 1.4 脳 10 ~ (-8), and the maximum coupling efficiency between the other modes is even lower. Crosstalk between the two cores will not adversely affect astronomical observation and meet the requirements of astronomical application. Based on the mode coupling theory, the excitation of the guide core of the five-core special star-image transmission fiber is calculated when it is connected with the step refractive index and the graded refractive index, respectively, and the relation curve between the excitation coefficient and the transverse deviation between the two fibers is obtained. When connecting with step refractive index fiber, the maximum excitation coefficient can be up to 90.94. The simulation results show that the spot of LAMOST system falls on the end face of fiber-optic fiber with five cores of special satellite image transmission, and the relation curve between the fundamental mode excitation coefficient and the radial offset of the spot in each core is obtained. It is proved that the optical fiber has offset feedback signal in the range of 100 ~ 349 渭 m. Five core special satellite image transmission fiber probe samples were prepared by intubation method. The alignment ability of the probe was measured by He-Ne laser as light source. The relationship between the intensity gray value of each core and the radial deviation of the spot was obtained. When the radial deviation of the fiber-optic probe is in the range of -305 ~ 155 渭 m and 10 ~ 5 ~ 270 渭 m, the guide core has an offset feedback signal when the five-core special satellite image transmission fiber probe is in the range of -305 ~ 155 渭 m and 10 ~ 5 渭 m respectively. The experimental results are in good agreement with the theoretical calculation.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH751;TN253

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