Determining the optical properties of blood using He-Ne laser and double integrating sphere set-up

Abstract

Abstract The behaviour of light interaction with biological tissue is determined by micro-optical parameters: refractive index (n), absorption coefficient (µa ), scattering coefficient (µs ), and anisotropy (g). The goal of this study is to measure the optical properties of normal whole blood using He-Ne laser (wavelength 632.8 nm). The refractive index is measured using the traveller microscope. The integrating sphere method is used to measure the macro-optical parameters: total diffusive reflectance, transmittance, and collimated transmittance at wavelength 632.8 nm. The macro-optical parameters are fed to Inverse Adding Doubling (IAD) theoretical technique, to estimate the micro-optical parameters (µs , µa , g). An alternative practical method is used to measure the g value based on utilising the goniometric table. The study reveals that the refractive index (n) equals 1.395±0.0547, absorption coefficient (µa ) equals 2.37 mm−1, scattering coefficient (µs ) equals 55.69 mm−1, and anisotropy (g) equals 0.82. In conclusion, these findings approved, in general, the applicability of the suggested experimental set up. The set up depend on using three devices: the integrating sphere method to estimate (µs , µa , g), traveller microscope (n) and goniometer (g).