Optical parameters detection with multi-frequency modulation based on NIR DPDW

For measuring the optical parameters of biological tissues accurately and rapidly, this study built an optical parameters measurement system based on near-infrared (NIR) Diffuse Photon Density Waves (DPDW) technology using frequency sweep modulation. The transmitted swept optical amplitude and phase can be nonlinearly fitted according to the physical diffusive approximation equation then to obtain the absorption coefficient and reduced scattering coefficient of the tissue phantoms, respectively. The experimental results of the 20 Intralipid solutions show that the average absolute errors of μ a and μ s ′ are 0.066 cm−1 and 0.716 cm−1, respectively, and the correlation coefficients between the measured and true values were 0.965 and 0.989, respectively. The experimental results of the 3 solid phantoms show that the average absolute errors of μ a and μ s ′ are 0.1140 cm−1 and 0.0023 cm−1, respectively. Therefore, the DPDW technology with frequency sweep modulation can detect the optical parameters of the tissue phantoms accurately and quickly, and it would be optimized for tissue tomography imaging and blood components noninvasively detection in vivo.