Theoretical And Technique Research Of Lensless Op-Tical Correlator Based On LCOS SLM

Represented as the key device in real time optical information processing, Spatial Light Modulators(SLMs) have been widely used in opto-electronic hybrid systems. Re-cently, with the rapid development of Large Scale Integration (LSI) technology, a kind of novel SLM named Liquid Crystal On Silicon (LCOS) SLM has been invented. LCOS SLMs are excellently suited to achieve pure, linear and precise phase control and fea-tured with high light utilization efficiency, high diffraction efficiency, high refresh rate et. al..Optical correlator based on LCOS SLM has been used in Automatic Target recogni-tion system. Compared with electric processing technology, optical correlator feature in high speed, parallel processing, large bandwidth et. al.. However, there exists some disad-vantages of traditional optical correlator, for example, complex system configuration, low signal-to-noise ratio (SNR), bad channel uniformity, and difficulty in optical path align-ment. In order to overcome these disadvantages, in this dissertation, we proposed Lensless Optical Correlator (LOC).LOC is based on two phase-only LCOS SLMs, both input and filter holograms are generated by superimposing phase-only Fresnel Lens Patterns (FLPs) on input and filter patterns. A method to improve SNR of correlation signal is presented by superimposing phase gratings on filter hologram.In the following, another kind of LOC which is composed with one LCOS SLM and a mirror is proposed. The input and filter holograms are displayed on the same LCOS SLM side by side.Next, we proposed multichannel LOC based on single channel LOC configuration. Two types of hologram generation techniques, spatial multiplexing and frequency mul-tiplexing, are introduced to realize multichannel optical processing. In the spatial multi-plexing technique, the input pattern is constructed by superimposing Fresnel Lens Array (FLA) on input targets. While in the frequency multiplexing technique, the input pattern is generated by superimposing input targets with different phase gratings.This LOC system is not only superior in compact design (f system), but also free from optical path alignment, it can adjust the optical path in three dimension space by modifying FLP on input hologram without moving hardware. Compared with LOC on two LCOS SLMs, single LCOS SLM LOC system is more compact and the cost is lower as it only utilizes one SLM. The advantage of multichannel LOC is parallel processing, besides, the optical path of each channel is adjustable in spatial multiplexing LOC, which leads to high channel uniformity is high compared with former optical correlator.Characters recognition and fingerprints recognition experiments are constructed to demonstrate the capability of LOC in low frequency and high frequency phase processing, correspondingly, the optical path alignment resolution is demonstrated to be±10μm in experiment. Moreover, experiment is constructed based on SNR improvement technique. Experimental results show the system SNR is improved from0.77to0.84. Through the experiments, the channel difference of4channel spatial multiplexing LOC is less than6%, the mean value and RMS of16and64channel spatial multiplexing LOC are148.63and23.07,191.56and31.38, correspondingly.Finally, we present a man-machine interactive holographic optical tweezers system based on LCOS SLM. The proposal system is characterized by convenient operation and friendly user interface, enabling manipulation on particles by simple click and drag with mouse.Some of the work is made in the4th research group at Central Research Laboratory of Hamamatsu Photonics K. K..