Speckle intensity correlation and optical diffusion profile in biological media

摘要

Short-range speckle correlation techniques were used to measure the refractive index of turbid biological media. The refractive index depends on the cell content, which is about 80% water and 15% protein. The variation in water or protein content produced various small shifts in the oscillatory features of the speckle intensity spatial correlation function for correlation distances shorter than the transport mean free path. Optical diffusion profiles in transmission, and long range speckle intensity correlation techniques were used to measure the transport mean free path. The optical system was calibrated with a porous silicate slab, and live yeast was the biological system studied. It is found that the techniques employed could serve as markers for the cell's water and protein contents. Consistent results were also found for chicken tissue and a combined yeast sample. Extension to abnormal cell detection, and the application to in-situ refractive index mapping are also discussed.