Research On High-Performance Fast Steering Mirror

Fast steering mirror (FSM) is a kind of optical scanning device, which is one of the most important components in the applications of light detection and ranging (lidar), adaptive optics, space optical communications, and so on. Domestic traditional FSM cannot meet the requirements of the high-end applications because of the limitation of their frequency, sizes, power consumptions and control. Laser scanners abroad in many fields are very mature, but advanced equipments importing are restricted due to the technology blockade policy of the western developed countries. Therefore, the research of laser scanner system for the high-end applications is urgent.This thesis gives an overview of the existing laser scanners. The performance of the existing foreign FSMs driven by voice coil actuator (VCA) and PbZrTiO3 (PZT) is presented. The composition and role of the hardware and software structure of the FSM is introduced. Three different FSMs based on two different actuators are fabricated. The primary content of the dissertation includes:In the aspect of the mechanical structure, the overall structures of the FSM are introduced, and the work principles are analyzed respectively. Key components which include the VCAs and amplified piezo actuators are simulated and calculated based on these different structures. And the optimized structures are obtained. In order to convert the output of the actuators to the suitable scanning deflection successful, the special consideration of the flexible support is necessary with the requirements of the frequency and angle. Different efficient flexible support structures are designed after simulation, measurement, modification and optimization for different FSMs. Different feedback structures for the detection of scan status are designed with the requirements of different structural layout and space size.In the aspect of the electrical design, common control circuits of the three FSMs are designed. Each unique drive circuit and signal processing circuit are set up for different FSMs. Feedback signal conditioning circuit and audio amplifier chip driver circuit for the two-dimensional (2D) FSM driven by VCAs are introduced. Isolation circuit based on the optical coupler for the soft start of VCA is designed. Cooling module is designed by the combination of demand of the chip cooling. Feedback circuit based on the resistance strain gauge and high-voltage driver circuit based on the separation device are introduced for the one-dimensional (1D) FSM driven by PZT. Notch circuit to restrain the resonant of the mechanical structure is set up. Corresponding to different frequency and the attenuation, the principle of the notch filter circuit is analyzed. Integrated high voltage driver circuit and signal conditioning circuit based on capacitive displacement sensor are achieved for the 2D FSMs driven by PZT.In the aspect of control algorithm, the signal noise filtering algorithm is designed and optimized to eliminate the effects of the noise in the signal acquisition to the control process. Three different control algorithms for the FSMs are described. A controller based on the model of the VCA is designed to realize feedback control in 2D scanning. The controller is used to reduce the oscillation of the FSM driven by VCAs at resonance frequency. To design a qualified controller, the model of the FSM is set up. The transfer function of the model is identified based on the tested data. The principle and method of amending the piezoelectric scanner hysteresis loop are analyzed for the 1D FSMs. The control algorithm based on self-learning feed-forward controller is introduced. The hysteresis characteristics are well restrained. For the unique support structure of the 2D FSMs driven by PZT, the driving algorithm is decoupled. Single-mirror 2D scanning driven by three actuators is simulated. The impact of the angle between the incident light and the mirror normal on the field of the view is analyzed.In the aspect of the performance measurement, a testing bench based on the position sensitive detector (PSD) and data acquisition card (DAQ) is built. Testing program based on virtual instrument is designed. The basic steps of the test are introduced. The scanning angle, scanning frequency and scanning linearity of three FSMs are testrd. The scanning performance of the FSMs is remarkably improved by controlling process.Finally, an array FSM for the multi-target detection and interference is introduced. The thesis laid the foundation fot the development of the array FSM.