The accuracy of a commercial spectrophotometer with single integrating sphere for measuring optical properties of turbid sample

A commercial spectrophotometer with an integrating sphere is widely used to measure the spectra of transmittance and reflectance of turbid sample, and then the optical properties can be deduced by inverse adding-doubling algorithm. Unfortunately, the accuracy of the measurement is not been elucidated completely. What's more, for the system, there still exists some other limits, i.e., the incident light is not collimated and size of light spot is too large compared with the sample port. Thus, the purpose of our study is to evaluate the accuracy of the commercial spectrophotometer with an integrating sphere for measuring optical properties of tissue phantom. Two phantom materials, Intralipid and Evans blue, and the mixture of these two, were chosen for the experiments. Mie theory was also introduced to calculate the reduced scattering coefficient according to the particle size distribution. The results show that the phantom measurement in conjunction with IAD algorithm enable the determination of scattering coefficient mu s' to be better than 5% accuracy, absorption coefficient mu a to be better than 10% accuracy when the optical depth of sample is between 1 and 10, and the albedo is bigger than 0.4. For scattering of samples during 1-5 mm(-1), the error of mu s' is smaller than 4%; whereas for absorbing of samples >0.4 mm(-1), the maximum error is smaller than 8.3%. Therefore, spectrophotometer with an integrating sphere technique combined IAD algorithm is applicable for the measurements of optical properties for most tissue, and its repeatability and accuracy is good in proper scope of the optical depth and albedo.