Optical parameters of biological tissues, including absorption coefficient (μa), reduced scattering coefficient (μs') or scattering coefficient (μs), anisotropy factor (g) and refractive index (n) are investigated extensively and systemically at
wavelength of 650 nm. Intralipid solution was selected to be the tissue phantom in order to test the validity of
measurements. Considering the factors of fiber orientation and haemoglobin content, we chose some fresh bulk animal
tissues in vitro which were bovine adipose, bovine muscle, porcine adipose, porcine muscle, porcine kidney, porcine liver,
mutton and chicken breast. The basic assumption is that in vitro samples are a reasonable representation of the in vivo
situation. We have gained numbers of experimental data of Intralipid and some tissues. Particularly, we have set up the
close relationships among six optical parameters involving μa, μs', μs, g, n and μt. The experimental results show that for
animal tissues, μa, μs' or μs and n rely deeply on muscle fiber orientations. Both of μs and μt range from 10mm-1 to 20mm-1. μa ranges from 10-2 mm-1 to 10-3 mm-1 and g from 0.95 to 0.99. The results of this study will be helpful in further understanding of optical properties of tissues.