Active line scan with spatial gating for sub-diffuse reflectance imaging of scatter microtexture.

We examine the value of an active line scan with spatial gating for imaging sub-diffuse, wide-field reflectance microtexture. Line scanning combined with spatial gating and linear translation can be used for localized detection of features in the surface layer of a turbid target. The line scan provides broadband spatial frequency modulation, and the spatial gating effectively high-pass filters the reflectance. The major benefit of this approach is that of high dynamic range (70%-90%) signal preservation and high contrast to noise when imaging at high spatial frequencies. Alternative approaches, such as spatial frequency domain imaging, are degraded by low dynamic range in demodulated images, making it nearly impossible to image over a wide field of view at frequencies over 1.5mm-1 using commercial technology. As such, active line scanning with spatial gating presents as an inherently high sensitivity and high dynamic range method of imaging microscopic scattering features in only the surface layer of a turbid medium.