The fabric of digital micromirror device (DMD) and its operation are presented. Based on analyzing the electronic circuits and control signals of several types of commercial DLP projectors, the circuits of the projector that relate to warm-up, inter-locked protection, UHP lamp control and testing and color wheel control and detecting are successfully separated. After having simulated these control signals by a digital logic circuit experimentally and applied them to the main control board of the projector, the DMD chip operates normally. The modulating and multi spectrum imaging properties of the modified DMD spatial light modulator are dealt with in details. A compact 4f Fourier transfer system is designed and assembled for multi spectrum coherent image read-out. As a practical use, an experimental setup for holographic stereograms is established using the modified DMD spatial modulator. The created synthetic holographic stereograms have high contrast and low noise. The fabric of digital micromirror device (DMD) and its operation are presented. Based on analyzing the electronic circuits and control signals of several types of commercial DLP projectors, the circuits of the projector that relate to warm-up, inter-locked protection, UHP lamp control and testing and color wheel control and detecting are successfully separated. After having simulated these control signals by a digital logic circuit experimentally and applied them to the main control board of the projector, the DMD chip operates normally. The modulating and multi spectrum imaging properties of the modified DMD spatial light modulator are dealt with in details.