Measurement of optical properties of biological tissues by low-coherence reflectometry

We show that optical properties of dense biological tissues can be determined from backscattered power curves measured by a low-coherence reflectometer. Our measurement approach is based on a first-order scattering theory that relates the backscattered power to the total and backscattering cross sections of scatterers in a turbid medium. As a validation of the technique, measurements were made with a commercially available reflectometer on suspensions of polystyrene microspheres having known optical properties. With this reflectometer, which employs a 1300-nm LED source that emits less than 20 µW, we found that skin tissues could be probed to a depth of nearly 1 mm. Estimates of optical coefficients of human dermis and of a variety of excised animal tissues are given.