Scanning technique for direct optical transmission imaging of highly-scattering objects

We present a spatial scanning technique for optical transmission imaging of strongly-scattering objects based on spatially-selective registration of ballistic photons originating from modulated (pulsed) laser radiation. The registration system counts the number of transmitted pulses at any pixel, forming a grayscale image. By choosing modulation regime, it is possible to record a real analog image or to outline contours of the image features, without necessity of software image processing. The developed system is tested on model scattering object (stack of paper) and biological object (human hand). Due to the automatic adjustment of the signal level, realized by the appropriate laser modulation mode, formation of an image with a structure uniformly pronounced across the aperture has been attained, even under conditions of significant changes in background transmission.