Computer simulation of spatial light modulators with micro optical elements

Highly efficient transmissive spatial light modulators are the key components of laser and LED projection displays. Collimated and spatially coherent laser light provides new possibilities in projection imaging by extended depth of focus and using microlens arrays. We present a method for investigation of microlens arrays, which reduce lateral dimensions of a light beamlet passing through each pixel of a spatial light modulator, down to dimension of micro-diaphragm that is created by TFT layer. In this method we exploit physical optics propagation combined with geometrical ray-tracing for both minimizing a diffraction spread and accounting for aberrations of each lenslet. It is mainly useful for designing and characterization of MLA with relatively high numerical aperture and complicated surface shape of each lenslet. Modeling the MLA enabled to predict such MLA parameters as focal spot size, longitudinal variations of spot size, transmission efficiency for given clear aperture of each pixel, output divergence of the cross talk between adjacent pixels and its minimization. Simulation data on combined effect of aberrated geometrical defocusing and diffraction spread is presented. Simulated spherical and elliptical lenslet shapes were used as a base for designing advanced spatial light modulators with high diffraction efficiency.