Optical diffusive imaging using Raman spectroscopy and laser speckle

Optical detection within diffuse media is a relatively new field whereby low energy photons are used to determine the internal structure of highly scattering media. The primary driving forces for this technology are medical imaging, medical diagnostics, and remote sensing. Use of low energy photons (typically visible and near IR) is not only safer than other traditional methods such as the use of x-rays, but can potentially supply a wealth of information about tissue structure and composition not available using conventional means. This research is aimed at two primary methods of diffuse optical detection. The first, speckle-based imaging, relies on the loss of coherence as photons traverse the multitude of random paths through the scattering medium. By imaging the speckle at the output of the medium, detection of heterogeneities is possible through various statistical methods. The second technique, Raman spectroscopy, relies on the nonlinear interaction between photons and matter to distinguish compositional differences within the matter. Molecules exhibiting distinct Raman signatures are detectable through lasers of scattering media, allowing for detection of distinct molecules within. This detection is useful in localizing objects having finite support, or determining relative concentrations of a dispersed species such as glucose