Holographic zoom micro-projection system based on three spatial light modulators.

In this paper, we propose a holographic zoom micro-projection system based on three spatial light modulators (SLMs). Three color lasers, three filters, and three solid lenses form the system's collimated light sources. Three beam splitters and a prism are used in the system for beam deflection. The SLMs are used as the micro-displays in order to realize phase modulation. A liquid lens, which consists of a circular hole in the center of the middle substrate and several holes around the center, is developed in the system and it. A receiving screen is located behind the liquid lens. When the voltage applied to the liquid lens is changed, the focal length changes accordingly due to electrowetting effect. Three color holograms are loaded on the SLMs, respectively. When three color lasers are used to illuminate the corresponding holograms, the position and size of each color reproduction image can be adjusted by changing the focal length of the liquid lens and holograms loaded onto the SLMs. Therefore, three color images can be reconstructed together perfectly. The proposed system can realize function of zoom micro-projection without chromatic aberration. The experimental results verify its feasibility.