Single wavelength measurements of absorption coefficients based on iso-pathlength point

Abstract

In optical sensing, to reveal the chemical composition of tissues, the main challenge is isolating absorption from scattering. Most techniques use multiple wavelengths, which adds an error due to the optical pathlength differences. We suggest using a unique measurement angle for cylindrical tissues, the iso-pathlength (IPL) point, which depends on tissue geometry only (specifically the effective radius). We present a method for absorption assessment from a single wavelength at multiple measurement angles. The IPL point presented similar optical pathlengths for different tissues, both in simulation and experiments, hence it is optimal. Finally, <i>in vivo</i> measurements validated our proposed method.