Multi-spectral random illumination using a liquid crystal spatial light modulator

Abstract

BackgroundUsing phase-only liquid crystal spatial light modulator (LC-SLM) to generate random illumination is always used in phase-retrieval and single pixel imaging as it have high energy efficiency. While the methods were only used to generate monochromatic illumination. This paper aims to use LC-SLM generating the multi-spectral random illumination.MethodsThe method requires only one SLM; multiple laser beams are simultaneously used to illuminate the entire SLM. Random voltages designed with a probability density function (PDF) are applied to modulate the random phases in the multi-spectral emitted light beam, leading to random amplitude spots in the far field. By optimize the PDF, the random illumination spot can be close to uniform distributed with high efficiency.ResultsThe average intensities of the random light spots are almost uniformly distributed within the range of the first diffraction order. And the zero-order beam is eliminated. The proposed method has a high energy efficiency and refresh rate and does not require the SLM to have an excessive modulation range.ConclusionThis paper provides a method to generate multi-spectral random illumination using a LC-SLM, which can be used in phase-retrieval and single pixel imaging.