Holographic Zoom System Having Controllable Light Intensity Without Undesirable Light Based on Multifunctional Liquid Device

In this paper, a holographic zoom system having controllable light intensity based on a multifunctional liquid (ML) device is proposed. The system consists of a collimated beam, a PBS, a spatial light modulator (SLM), an ML device, and a receiving screen. Different from the traditional liquid device, the ML device, which consists of the aperture-change part, the focal-length-change part, and the light-intensity-change part, is proposed. The aperture-change part and the focal-length-change part are actuated by the electrowetting effect, and then, the aperture size and the focal length can be changed. In the light-intensity-change part, two polarizers are stuck on the top substrate and the bottom substrate, respectively. By controlling the voltage applied on the liquid crystal cell, the light intensity can be changed easily. When the collimated beam illuminates the SLM, the phase of a spherical wave is loaded on the SLM. By adjusting the radius of the spherical wave and the focal length of the ML device, holographic zoom function can be realized. When diffraction images pass through the ML device, the reconstructed image can be displayed without diffraction beams and high-order diffraction images. Moreover, the size and intensity of the reconstructed image can be adjusted conveniently with such a simple system. The experimental results verify the feasibility of the proposed system.