Preliminary Research Of Active Optical Zoom System Based On Spatial Light Modulator

Optical zoom system has very important applications in the optical imaging system.In order to optically vary the magnification of an imaging system, continuous mechanical zoom lenses require multiple optical elements and the use of fine mechanical motion to precisely adjust the separations between groups of lenses. Although traditional mechanical zoom can change the magnification and adapt to changes in the shape of the actual size of the object, it demands very high in mechanical construction because mechanical optical zoom system lens group needs to be moved very precisely. Allowing for the size, the price and the rate of reaction of the lens, incorporating active elements into the optical design is proposed in this thesis. In this way, it’s possible for imaging systems to realize optical magnification without moving macroscopic parts. Active optical zoom system has more advantages than the traditional mechanical zoom. It is smaller, more flexible and more convenient.The spatial light modulator (Spatial Light Modulator,SLM) is a kind of electronic programmable device. It can modulate transmission and reflection of light, modulate the light wave amplitude, phase, frequency. This article introduces the reflective electrically addressed liquid crystal spatial light modulator-LCOS (liquid crystal on silicon). Through the application of the LCOS liquid crystal spatial light modulator as the active optical components, we can build active optical zoom system and investigate the optical zoom function.The main works and contributions of this thesis are outlined as follows:1) The phase modulation characteristics of two different types of LCOS are determined by equal inclination interference method. It can be measured that Aurora Systems, pixel pitch is8.0μm LCOS phase modulation range is close to π, the Three-Five Systems, pixel pitch is12.0μm LCOS phase modulation range is close to2π.2) An imaging system with digital lens is set up followed the objects imaging with optical lens. Active optical element is introduced and corresponding active optical zoom imaging system is build up. Experimental results show that the preliminarily function of optical zoom under coherent light and partially coherent light have been demonstrated.