Transport properties of optically thin solid dielectrics from frequency correlations of randomly scattered light.

Frequency-dependent intensity correlation function measurements can be employed to determine the optical turbidity of solid disordered dielectrics. Here we demonstrate a speckle frequency correlation experiment with a focused beam and using an area detector. We show how to apply frequency correlation measurements to optically thin solid samples with the aim of determining the light diffusion coefficient and transport mean free path ℓ*. To give a practical example, we extract the optical transport mean free path of PTFE (Teflon) slabs, with a thickness of L = 0.4-3.5 mm, covering optical densities L/ℓ* ∼ 4-15.