The scattering phase function (the probability distribution of the scattering angle) is intimately associated with the cellular organization and ultrastructure of tissue. Since these physical parameters change during e.g. carcinogenesis; quantification of the phase function and related parameters may allow for improved non-invasive, in vivo discrimination between healthy and diseased tissue. Furthermore, for the derivation of models to interpret measured optical signals, assumptions about the phase function of tissue are often made – regularly assuming a Modified Henyey Greenstein. However, in contrast to other optical properties, the phase function has not yet been extensively measured for different tissue types.
With conventional goniometers, the exact backscatter direction of 180 degrees cannot be measured. Especially for techniques that detect backscattered light – such as Optical Coherence Tomography and Elastic Scattering spectroscopy – the details of the backward part of the phase function will have a considerable impact on the measured signal.
We have therefore developed a setup that can measure the backward part of the phase function: 134 to 180 degrees. Our design is based on full field Optical Coherence Tomography. We detect all angles simultaneously with a camera, while scanning the reference mirror. The phase function scales with the amplitude of the OCT signal for each angle. We will show our results for validation measurements on two silica bead samples of 200 nm and 400 nm beads.
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