Eliminate The Zero-order Diffracted Light And The Background Noise. Digital Holography

Digital holography is a novel optical technology, which combined by conventional optical holography and computer technology. Besides of the advantages of conventional optical holography, it also has its special superiorities. It mainly manifested in avoiding the chemical processing of plate, and it is more convenient to get the phase of wavefield in observation direction. In recent years, digital holography is a focal in the studies of information optics, but its theoretical study is not enough system and maturity. In spite of the separation of several diffraction images can be completed by using off-axis reference light in the processing of digital holography reconstruction, but the reconstructed image is also ambiguous due to the interference of zero-order diffraction light and conjugate image. So it is important to eliminate the zero-order diffraction light and conjugate image. The major job of this paper is a discussion on the method of how to do it.This paper takes digital real-time holography which detect small rotation of aluminum washer for example, gives a brief discussion on the features of scattered light digital real-time holography technology, and also gives a comparison between two methods of eliminating zero-order diffraction light technology based on one or two hologram images in the research. The result indicates that under the premise of time which is longer than the CCD response time, the key to realize corret measurement is choose the smaller measurement time-interval as far as possible. In addition, technology of eliminating zero-order diffraction light can enhance measurement result's signal-to-noise ratio effectively. But for real-time detection, to guarantee the measurement quality, echnology of eliminating zero-order diffraction light based on one interference image should be used as much as possible.