VOLUMETRIC RAMAN MICROSCOPY THROUGH A TURBID MEDIUM

The need for safe and non-invasive techniques for in situ structural a nd functional analysis of biological tissue has motivated widespread i nterest in optical spectroscopic-based imaging methods. Inclusion of s pectroscopic information in the image data set can improve image contr ast and, more importantly, provide for in situ histochemical tissue an alysis via spectrochemical differences between tissue types. A promisi ng approach utilizes the inherent spatial and spectral discrimination properties of the confocal Raman microscope (CRM) to isolate and extra ct 3D spectrochemical information from objects embedded in a scatterin g matrix. This study had several objectives. First, it is shown that a wax film immersed in a turbid solution of milk and water is a valid m odel system that replicates the elastic scattering properties and Rama n activity typical of many biological tissues. Subsequently, the CRM s patial resolution (both axial and lateral) was measured as a function of solution turbidity with the tissue-equivalent phantom and the resul ts were compared with those derived from a theoretical model of CRM im age formation based on single scattering theory. The good agreement be tween the theoretical predictions and experimental results allowed lim its to be established for confocal Raman spectroscopic imaging through a scattering tissue-like medium.