Optical properties measurement of highly diffusive tissue phantoms for biomedical applications

Extensive research in biomedical optics essentially requires the determination of optical properties of various biological tissues. Quantitative characterization of biological tissues in terms of optical properties is achieved with an integrating sphere. However, samples having significantly higher scattering and absorption coefficients such as malignant tissues potentially reduce the signal-to-noise ratio (SNR) and the accuracy of an integrating sphere. We describe the design, implementation and characterization of a modified sample holder (path length of up to 1 mm) for an integration sphere. Experiments conducted with various phantoms reveal significant improvement of the SNR for a wide range of optical properties. The alternative approach opens up potential applications in the measurement of optical properties of highly diffusive biological samples. For 20% intralipid mu(a) = 0.112 +/- 0.046 cm(-1) and mu(s) = 392.299 +/- 10.090 cm(-1) at 632.8 nm. For 1.0% Indian ink mu(a) = 9.808 +/- 0.490 cm(-1) and mu(s) = 1.258 +/- 0.063 cm(-1) at the same wavelength. The system shows good repeatability and reproducibility within a 4.9% error.