Reflectance calibration of multimode optical fiber probes by probe-to-target distance reflectance profile modeling

Abstract

Reflectance acquired with a multimode optical fiber probe can be related to optical properties of an investigated turbid medium by utilizing a light propagation model. During this step, a calibration of the light propagation model is required, as the modeled reflectance is normalized to the light energy of the source fiber, while the experimentally acquired reflectance is normalized to a reflective standard. Since currently established calibration methods based on liquid and solid turbid phantoms suffer from drawbacks such as low stability and dependence on other characterization methods, we propose a new method for reflectance calibration that is based on modeling and acquisition of probe-to-target distance reflectance profiles from first surface mirrors. We show that the spectrally resolved calibration factors can be estimated with a repeatability of 2% and agree within 10% with the reference values obtained by using turbid phantoms based on aqueous suspensions of polystyrene microspheres.