Depth-sensitive reflectance measurements using obliquely oriented fiber probes

Computer simulation was used to facilitate the design of fiber-probe geometries which enable enhanced detection of optical signals arising from specific tissue depths. Obtaining understanding of the relationship between fiber-probe design and tissue interrogation is critical when developing strategies for optical detection of epithelial pre-cancers which originate at known depths from the tissue surface. We investigated how the depth of optical interrogation may be controlled through combinations of collection angles, source-detector separations and numerical apertures. We found that increasing the obliquity of collection fibers at a given source-detector separation can effectively enhance the detection of superficially scattered signals. Fiber numerical aperture provides additional depth selectivity; however, the perturbations in sampling depth achieved through this means are modest relative to the changes generated by modifying the angle of collection and source-detection separation.