Instrument for noninvasive photonic assessments of biological materials

Abstract

We have developed a new instrument for non-invasive assessments of biological materials. A new technique was implemented to measure the light-tissue interaction in samples using an efficient light delivery and detection method. The optical properties measured were, transmitted, forward scattered, diffusely reflected and specularly reflected light. Measurements were made using a white light source, as well as with spectrally-resolved signals. Using artificial, human, and rabbit corneas as models, measurements were made to determine correlations of the above optical properties in the different tissues. The instrument repeatability using non-biological controls, was between 0.1% and 0.2% for the measured optical properties. The repeatability was consistent even at low light conditions of 0.01 to 0.05 relative intensity. The instrument repeatability was better than the variability of samples within a test group. For both transmitted and reflected non-specular light, there was an equivalent correlation measured between artificial and human corneas. The instrument also proved useful in tracking time-dependant responses of biological tissues subjected to various insults. This new instrument is a reliable tool for measuring static and dynamic optical properties of various biological tissues. The ability to measure small relative changes in optical properties of tissues make it an invaluable diagnostic tool.