Research On Controlling Methods Of DMD Based On FPGA

Digital micromirror device(DMD)is a highly-performed spatial light modulator(SLM).It is widely used in the digital lithography,the 3D volumetric display with rotating mirror and other fields.The performance requirements of DMD are discrepant in different applications.In digital lithography,DMD is used to display grayscale images to complete 3D lithography.At the same time,DMD is used to scroll the display to complete scanning lithography.However,the transmission and storage of large-scale gray image data cannot be performed well by current methods.The gray images and their bit-planes must be split when they are rolling displayed,which is inefficiency.DMD is required to refresh the hologram at ultra-high frame rate in the 3D volumetric display.The binary image can be displayed at ultra-high frame rate by existing DMD equipment,while part of the holographic information will be lost.The controlling methods of DMD based on FPGA are researched to address the above mentioned issues.The main work of this thesis are as follows:(1)In the application of digital lithography,a high frame rate 8-bit gray-scale with 419.6Hz modulation method is completed according to the specifications of DMD by FPGA.At the same time,the computer software and the data receiving module in FPGA are improved so that the large-size gray image data can be directly transmitted,which simplifies the workflow of the DMD display device.(2)An interval storage method is proposed to realize the storage of large-size image data.The scrolling display of grayscale images is completed by the method.The DDR2 readwrite controller is ameliorated to increase the reading bandwidth of DDR2 Memory.Hence the DDR2 bandwidth is no longer a factor restricting the frame rate of DMD display.At the same time,the image data can be stored by the DDR2 read-write controller and FIFOs while loading the DMD data.(3)The DMD controller is optimized to meet the performance requirements of the 3D volumetric display with rotating mirror.A high-frame rate image modulation method is designed in order to reduce the loss of holographic information and improve the quality of 3D object reconstructions.Thus the display content of DMD is promoted from 1-bit images to 4-bits images and the frame rate is maintained highly enough simultaneously.