Measurement of optical pulsation and transmission spectra as reference for a Monte Carlo simulation of the finger tip

摘要

To validate a Monte Carlo simulation of light propagation in the finger tip, reference transmission and pulsation spectra are required. To obtain them, the following method is applied: A fingertip is illuminated by halogen light, and the light that passes the fingertip is recorded by a spectrometer. By comparing a reference spectrum of the light source and the transmitted spectrum, the static transmission spectrum is calculated. Furthermore, from the variation of the transmitted light spectrum in time, a pulsation amplitude spectrum is deduced which contains the change of transmission due to the pulsation of arterial blood. This spectrum resembles the in-vitro spectrum of the effective attenuation coefficient of arterial blood. In a wavelength range from 600 nm to 1300 nm, the methods described in this paper have shown to produce spectra which are suitable to serve as reference for the Monte Carlo simulation.