关键词: 重力安平, 临界阻尼条件, 磁阻尼器, 扩束系统, 费马原理, 聚焦镜

Abstract: When we use the laser image method to measure the deflection，the case whether the laser transmitter can automatically adjust the level，the length of adjusting time and the size of the projected spot have direct impact on the accuracy of the deflection monitoring. So，a laser system of self-adjusting level for deflection monitoring is designed. Gravity pendulum is used for self-adjusting. Through the analysis of stress and trajectory of the gravity pendulum，critical damping conditions are used to determine damping coefficients and to adjust the electromagnetic damper magnetic induction intensity and the drag coefficients，which finally realize rapid hovering. In order to maintain good concentration of energy when laser is shooed in long distance，Fermat Theorem is used to design the corresponding focusing lenses，which are combined with the Galileo beam expander to compose the laser lens to realize long distance shoot. The laser lens parameters and the electromagnetic damper parameters are obtained after analyzing and deducing. The achievement provides theoretical foundation for the appearance of the real laser emission device.

Key words: self-adjustinglevelbygravity, criticaldampingconditions, reluctancedamper, beamexpander, Fermat＇sprinciple, focusinglens