Characterization and optimization of liquid crystal displays for data storage applications

We present the characterization and the optimization of the phase and amplitude modulation of a liquid crystal display (LCD) applied to holographic data storage. We discuss the main LCD modulation regimes demanded in the literature in the application to holographic memories: binary amplitude, binary phase and hybrid ternary modulation (HTM). We show how to obtain optimally these modulation regimes with a LCD. In our strategy it is essential the accuracy demonstrated by the model we use to describe the modulation properties of the LCD. This accuracy allows for a reliable computer search of the configurations enabling for an optimum LCD complex amplitude modulation. Results are given for the calibration of a commercial LCD. Optimum configurations close to the ideal for each of the modulation regimes are also obtained and the values of the various parameters characterizing the quality of these configurations are provided. We have also analyzed the performance of these configurations to perform the Fourier transform (FT) of a binary data page. We see that the optimum configurations obtained for the binary phase and the HTM regimes produce a homogeneous distribution of the energy in the Fourier plane with no DC peak.