The Study Of Fast Steering Mirror In The Acquisition, Pointing And Tracking System Of The Space Laser Communication

Fast steering mirror(FSM)works between the light source and the receiver,which is used to adjust and stabilize the optical axis or light beam.The mirror is driven by the actuation to deflect,and it can adjust the beam propagation direction,therefore,the FSM has been the key component in the acquisition,pointing and tracking(APT)of the space laser communication.It also has been widely applied to some other fields,such as astronomical telescope,image stabilization and the adaptive optics because of its advantages of high accuracy,high bandwidth and high resolution ratio et al.Based on a laser communication platform,the research of the two kinds of FSMs respectively using flexure hinge support and cross-flexure bearing support has been performed in detail.The detail contents were described respectively as follows:According to the requirements of the fast steering mirror used in the the two kinds of laser communication platform,a scheme design and the performance indicators of the FSM were analyzed and presented.Two FSMs using flexure hinge and cross-flexure bearing were designed respectively.Both of the two FSMs use voice coil actuator(VCA)and the position detecting system based on the QD,and they were compact and stable with no friction and clearance.The flexure hinge with different notch shapes and the performance were summarized.A novel hyperbolic-circular flexure hinge was presented after comparative analysis,it simultaneously achieves the wide rotation range like the hyperbolic flexure hinge and the high rotation precision like the circular flexure hinge.In order to make it easier to optimize the design of this flexure hinge,its compliance formula was deduced.And the relationship between the compliance and the parameters was analyzed,which improve the design efficiency for the hyperbolic-circular flexure hinge.In addition,the compliance formula of the cross-flexure bearing was deduced,and the fatigue life of those two support structures were simulated and analyzed,it was shown that the two supports satisfied the design requirements.The symmetrical reflective position detecting system based on the QD was presented,and its mathematical model was established.Based on the model,the variation trends of the measurement range and linearity with the main parameters were simulated and analyzed,and method of optimizing deflection angle and nonlinearity of FSM is demonstrated.Then,the experiment platform was set up to verify the feasibility and effectiveness of the optimization method,and finished the design of FSMs.The simulation analysis of the resonant frequency and kinematics of the whole system was carried out.First of all,the kinematic models of the two FSMs were built according to the model analysis theory,and the first six order mode was simulated.Then,the transfer functions of the two FSMs were built according to the moment balance equation of the system and the voltage balance equation of the VCAs.Based on the obtained transfer functions,the resonant frequency in the working direction was simulated.Those two methods to simulated resonant frequency were verified reliable and high efficient to design the FSM by comparing the resonant frequency obtained by the two methods.The design,machining and assembling of the two FSMs were finished,and in order to test the static and dynamic characteristics and performance indicator of the FSMs,the experiments were set up,respectively.The experiment results showed that: the static and dynamic performances of the two FSMs can satisfy the requirement of engineering design.Comparing the FSMs in this paper with others,it was shown that the hyperbolic-circular flexure hinge really improve the deflection angle and the rotation precision;the position detecting system based QD efficiently improved the deflection angle and linearity and insured the high closed-loop bandwidth,simultaneously.