Implementation of a real-time differential path-length spectrometer system

We report on the development of an optical-fiber-based diagnostic instrument to determine the local optical properties of a turbid media. The system relies on making differential diffuse reflection measurements. We present a method to correct for the variations in the spectral characteristics of the two spectrometers. We also introduce a novel method to evaluate the differential reflectance by encoding a relative wavelength sensitivity constant into the signal processing to account for differences in the spectral sensitivity between spectrometers. This method allows us to record differential reflectance without needing to make additional reference measurements before an experiment to account for spectral variation of the lamp.