LCOS Holographic Imaging Based On The Calculated Axicon Phase

Spatial light modulator plays an important role in real-time signal processing. As a kind of spatial light modulators, Silicon based liquid crystal (LCOS) technology has been grafted on the advantages of liquid crystal and CMOS Technology, with high diffraction efficiency, large aperture, high resolution, low power consumption and so on. At the same time, as a kind of electronic addressing and modulation device, the characteristics of the coding based on the pixel programmable modulation is to achieve a strong function of a variety of diffractive optical elements. A variety of diffractive optical elements can be realized dynamically by specially designed LCOS application software. Actually, the calculation of LCOS technology is itself a novel research field, which can effectively improve the system architecture of holographic device for 3-D display.In this paper, the pure phase modulation LCOS is used as the platform, where the computational optics and diffractive optical elements are effectively combined to investigate the application of diffractive optical elements in the holographic display. The main research work and innovations given by this paper are summarized as follows.(1) Based on a review of the existing LCOS application software, we designed a LCOS computing software based on the MFC and OpenCV library which has a powerful image processing function and provides a rich platform for the display. Through the combination of optical and computational methods, a variety of diffractive optical elements (such as blazed grating, the phase of the spherical lens, the phase of the linear axicon, the phase of the logarithmic axicon and so on) are realized. At the same time, the software integrates the functions of LCOS calibration and computer generated hologram, and builds a bridge between the computational optics and LCOS devices.(2) The depth of focus is especially important when 3-D scenes or 3-D objects are imaged. The earlier LCOS holographic display system based on the computation of spherical phase loading can effectively reduce the use of the physical lens and realize the holographic imaging of the focal plane corresponding to the phase of the spherical surface. In this paper, we extend the focus range of the holographic display from the focal point to the depth of the focal line by using the numerical axicon phase instead of the spherical one. The imaging characteristics of holographic display can be effectively improved by using the properties of the focal line of the axicon. Further, by introducing the combined effect of the imaging lens with the axicon phase, we realized the spatial separation of zero order light and holographic reconstruction image and can easily use the aperture to eliminate the zero order light effect on holographic display.