Spatial Modulation Characteristics Of Micro-lens For Irradiated Laser

With the development of optoelectronic technologies and communication technologies,micro-lens has been widely used in various types of optoelectronic systems.The traditional research on the interaction between the micro-lens and laser mainly focuses on echo intensity.However,the aperture of the micro-lens target can generate an obvious diffraction phenomenon for the reflected echo.The research based on the diffraction effect of the aperture becomes another important research project.The study on the formation mechanism of laser diffraction pattern can enrich the theory of the interaction between micro-lens and laser and provide theoretical and experimental groundings for the identification of miniature camera devices,detection and other applications.On the basis of theoretical model and analytical method of "cat’s eye effect" reflected light,this paper analyzed the feasibility of different diffraction integral theories for the diffraction effect of micro-lens aperture and established the suitable angle spectrum diffraction integral theory for laser large angle oblique incidence.Based on the angular spectral diffraction integral theory,the aperture diffraction phenomenon of a micro-lens was analyzed and the theoretical models under the condition of normal incidence and oblique incidence of the laser were established.Six distance points in the distance range of 0 to 3 meters and six distance points in the incident angle of 0 to 5degree were simulated to explore the effects on the distribution of the diffracted light field,respectively.The effects of laser wavelength and laser divergence angle on the distribution of diffraction light field were analyzed.The influence of laser wavelength and laser divergence angle on the diffraction field distribution was analyzed.The influence of the relationship between the factors such as the number of pattern pixels,the center spot energy,the center spot radius and the laser wavelength on the diffraction pattern was simulated.The influence of the incident laser divergence angle on the diffraction pattern and the influence of the focal length and aperture diameter on the diffraction pattern were simulated.In order to verify the feasibility of the theoretical model,a microscopic experiment of the spatial modulation of irradiated laser was carried out.Using polarizing beam splitting prism and ?/ 4 wave plate,the same transceiver requirement of the experiment was achieved.The spatial modulation experimental equipment for the irradiated laser was built.The influence of each factor including the distance between the laser source and the micro lens,the incident angle of the laser,the wavelength of the laser,the divergence angle of the laser,the focal length of the micro lens and the aperture diameter of the micro lens on the diffraction pattern was verified.The result was in comparison with the simulation design and the error reason was further analyzed.The experiment results show that the experimental data matches well with the simulation data,and the feasibility of the space modulation theory model for the irradiated laser is proved.