Design Of Opto-mechanical System For High Accuracy Laser Remote Detection

Laser remote detection is a combination of laser,atmospheric optics,target and environmental characteristics,radar,the integration of optics,mechanics,electronics and computer technology.With the development of lasers,laser remote detection has become a technology of photoelectric information detection,monitoring and collection since the 1960 s.After half a century of development by leaps and bounds,laser remote detection has been widely used in national economy,daily life and national defense construction.Under this background,the research of opto-mechanical system for two kinds of high accuracy laser remote detection has been studied.According to the project requirements,this dissertation focuses on the key technology for the design of the opto-mechanical system.The relevant solutions have been put forward,and good performance is achieved in the applications.The major research contents are as follows:Firstly,the principle of heterodyne detection is analyzed.The atmospheric wind speed and direction are analyzed with Doppler effect by measuring the frequency shift between the atmospheric aerosol scattering echo signals and the laser emission.A complete and compact 1550 nm coherent wind lidar system connected by single-mode polarization-maintaining optical fibers and free space is introduced.The optical parameters of the coherent wind lidar are analyzed based on the normalized signal-to-noise ratio.According to the RMS wavefront deviation under ?/10@1.5?m,a mathematical modeling method of 120 mm aperture off-axis telescope is presented,and there is no focus inside the telescope.Then,an optomechanical design for a low-cost and high-quality telescope with several special engineering challenges is illustrated.According to mode matching theory,the coupling efficiency of arbitrary light and single-mode optical fiber is studied.When the incident light is regarded as a plane wave,the relationship between the coupling efficiency and the relative aperture of the coupled lens is analyzed emphatically.The relative aperture with the optimal coupling efficiency is obtained.The relationship between the coupling efficiency and the alignment error is analyzed in detail.The coupling lens is designed based on third-order aberration theory.The overall integration of coherent wind lidar prototype is participated.Experimentally,the efficacy of the prototype has been verified.The Beijing Institute of Technology coherent wind lidar exhibits a 3 km wind measurement range.The principle of fluorescence spectrum generation is analyzed.With considerations of fluorescence characteristics such as short lifetime,low intensity and wavelength sensitivity,the laser-induced fluorescence remote detection with 266 nm and 355 nm dual-wavelength is proposed.The imaging principle and the aberration distribution of the classic Cassegrain telescope is studied in detail.The Cassegrain telescope with 160 mm aperture is designed and the tolerance is analyzed.According to the requirements of spectral measurement for laser-induced fluorescence remote detection,combining the theory of aberration,the aberration correction of the Czerny-Turner spectrometer is studied in depth.An advanced optical design for miniature spectrometer is presented.Reflective plane diffraction grating is adopted as the dispersion element.The theory and method of astigmatism correction are determined with the use of a concave toroidal mirror.In the design of the spectrometer,three factors affecting the spectral resolution of the optical system are considered: the width of the entrance slit,the pixel size of the detector and the aberrations.The opto-mechanical structure of the miniature spectrometer is designed and analyzed.A mercury lamp,473 nm and 663 nm minature solide-state laser are used to assemble the designed miniature spectrometer.The wavelength calibration of the miniature spectrometer uses the method of the least squares four polynomial fitting with a mercury lamp.The spectral measurement and collection are conducted by the laser-induced fluorescence remote detection prototype.The actual experiments indicate that that the center spectral resolution is less than 2nm and the edge spectral resolution is less than 0.3 nm over the broadband working wavelength from 290 nm to 650 nm.In order to improve the portability of miniature spectrometer,the improved miniature spectrometer is developed for a wider range of applications.