| In recent years,the rapid development of mobile intelligent devices such as head-up display,smart glasses,head-mounted display and projection phone requires "embedded" micro-projection with smaller size,higher resolution and larger field of view.The laser micro-projection technology with laser as the light source and MEMS mirror scanning as the driver has many advantages,such as electronically controlled field Angle and resolution,high brightness,low loss and no need to focus,etc.In this thesis,the laser micro-projection technology based on MEMS scanning mirror was deeply studied.The main research contents are as follows:(1)The feasibility of the design scheme of laser micro-projection system was verified theoretically.The working principles of common light sources for micro-projection was analyzed,in which semiconductor laser was used as micro-projection light source because of its small size and easy modulation.The model of raster scanning analysis based on two one-dimensional MEMS scanning mirrors was built in MATLAB.The pincushion distortion of the scan pattern in the model was corrected by quadratic curve method.(2)The optical system of laser micro-projection was designed.To meet the key indicators of P720 resolution and 73? field of view,collimating lens for blue laser diode with 21? of fast axis divergence and 7? of slow axis divergence was designed in ZEMAX software.After collimating the light spot diameter was ?m200.A relay scanning multi-structure system based on MEMS scanning mirror was designed to expand the scanning angle of X scanning mirror and match the mirror size of Y scanning mirror at the same time.(3)The display scheme of image source drive circuit was designed.The drive module is mainly composed of the laser modulation circuit,the drive circuit of X scanning mirror with the drive frequency of 41738 Hz,the drive circuit of Y scanning mirror with the scan frequency of 30 Hz,and the FPGA control chip.The synchronization between the laser and the two MEMS scanning mirrors was controlled by FPGA.(4)The complete micro-projection display system was built.The system consists of optical system and driver module.Collimated by two cylindrical aspheric mirrors in different directions,the divergence Angle of the light source is 2.3mrad.The size of the scanning system is ??mm10mm8mm8.After debugging the system and correcting pincushion distortion by software,the scanning display of the monochrome binary image is correct,and the resolution is up to 720 P.The frame rate is 60 Hz,and the field of view is up to 65°.Experiments show that the "embedded" micro-projection system with high resolution and large field of view can increase the field of view and resolution of the projection by the relay scanning system while keeping the smaller size,which has broad market prospect.It is of great significance to research and develop the micro-laser projection. |
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