Micromachined silicon collimating detector array to view objects in a highly scattering medium

摘要

Materials such as turbid liquids and tissues absorb light very weakly, but scatter it very heavily. Detection of objects within such mediums is difficult as the scattered light obscures their presence. However, using laser light and a very-high-aspect-ratio silicon micromachined collimator array (SMCA) aligned to a CCD array, one can detect objects through centimetre of a highl scattering medium. When a collimated laser beam enters a random turbid high-scattering medium, the photons spread into ballistic (unscattered), scatteredd and absorbed components. Consider light (ballistic photons) entering a very-high-aspect-ratio (200:1) micromachined collimating array consisting of 50-μm-wide etched channels with 100-μm spacing over a 10-mm width of silicon.