Study Of Pixel-level Light Modulating Technology Based On DMD

With the development of science and technology,there is an increasing demand for research in the field of high dynamic range imaging such as deep space detection,military detection and surface detection of strong reflective objects in industrial manufacturing.However,limited by the potential well depth of the charge coupled device(CCD),the application of the CCD camera to the imaging of strong light targets in the above fields is limited.Therefore,there is necessity to further develop imaging technologies to extend applications of CCD camera.Optical information modulation technology is an important part of the emerging computational imaging technology.The imaging system can modulate the intensity of the incident light signal and enhance the dynamic range of the camera utilizing a spatial light modulator.Digital micro-mirror device(DMD)is the most advanced and widely used reflective space sight modulator.It consists of millions of independently programmed and controlled micro-mirrors,each of which can perform high-speed state switching through binary pulse width modulation.In this paper,a DMD is used to build an imaging system that can accurately modulate incident light information.Meanwhile,an accurate pixel-topixel mapping in this imaging system using absolute phase method is proposed.Finally,the experiments prove the accuracy and applicability of the mapping method and the modulating capability of the imaging system.The main works of the paper are embodied in three aspects:(1)An imaging system based on a DMD that modulates the intensity of incident light in pixel level is built.According to the experimental requirements,the optical path of the system has been optimized to improve the imaging quality.(2)A precise pixel-to-pixel mapping algorithm in this imaging system using absolute phase is proposed,and compared with the traditional polynomial distortion fitting algorithm and back propagation(BP)neural network fitting algorithm base on the match and alignment between DMD mirrors and CCD pixels.Experiments show that the mapping error of absolute phase method is within(-0.6,0.6)pixel,which is more accurate than the polynomial distortion fitting algorithm and BP neural network algorithm.(3)The response curve of the modulating system is calibrated,and the intensity modulation and high dynamic imaging of the gauge block with high-brightness surface is performed.