Performance Analysis of Adaptive Optimization of Multiplexed Phase Fresnel Lenses

Although a computer-generated hologram that is sufficiently optimized has high quality in computer reconstruction, the quality decreases in a real optical reconstruction system. To overcome this issue, we implemented an adaptive scheme that compensates for the spatial properties of the real optical reconstruction system with a liquid-crystal spatial light modulator and feedback control based on estimation of the reconstructed diffraction pattern. We demonstrated adaptive optimization methods for multiplexed phase Fresnel lenses. We used two optimization methods: one based on regulation of the numerical aperture of each phase Fresnel lens, and the other the phase depth. The methods had high controllability of the diffraction peak intensities and significantly improved the uniformity of the peaks in the optical reconstruction. Furthermore, to determine the origin of residual error after the adaptive optimization was performed sufficiently, we also investigated the temporal characteristics of the spatial light modulator. The temporal variation of the diffraction peak intensity, derived from the phase fluctuation of the spatial light modulator, was observed. This variation was comparable to the residual error.