Fast noniterative data analysis method for frequency-domain near-infrared spectroscopy with the microscopic Beer–Lambert law

By using the microscopic Beer–Lambert law (MBL), we propose a fast and effective analysis method for retrieving the absorption coefficient changes of a sample from broadband frequency-domain diffuse optical spectroscopy (FD-DOS) or frequency-domain near-infrared spectroscopy (FD-NIRS) data. To verify the advantages of our proposed method, we built a broadband frequency-domain single-distance diffuse optical imaging (DOI) system for measuring the amplitude and the phase of transmitted light. Fifteen liquid phantoms with different absorption and scattering coefficients are prepared, and the changes in the absorption coefficient Δμ_a are retrieved by using the conventional nonlinear least-squares fitting (NLSF) and the proposed MBL methods. Results show that the computation time and the precision of the MBL method are much better than those of the NLSF method, respectively.