Assessment of incident intensity on laser speckle contrast imaging using a nematic liquid crystal spatial light modulator.

Before laser speckle contrast imaging (LSCI) can be used reliably and quantitatively in a clinical setting, there are several theoretical and practical issues that still must be addressed. In order to address some of these issues, an electro-optical system that utilizes a nematic liquid crystal spatial light modulator (SLM) to mimic LSCI experiments was assembled. The focus of this paper is to address the issue of how incident intensity affects LSCI results. Using the SLM-based system, we systematically adjusted incident intensity on the SLM and assessed the resulting first- and second-order statistics of the imaged speckle to explain the corresponding spatial contrast values in both frozen and time-integrated speckle patterns. The SLM-based system was used to generate speckle patterns with a controlled minimum speckle size, probability intensity distribution, and temporal decorrelation behavior. By eliminating many experimental parameters, this system is capable of serving as a useful intermediary tool between computer simulation and physical experimentation for further developing LSCI as a quantitative imaging modality.