Speckle Size in Optical Coherence Tomography

摘要

Speckle is inherent to any Optical Coherence Tomography (OCT) imaging of biological tissue. It is often seen as degrading the signal, but it also carries information about the tissue microstructure. One parameter of interest is the speckle size. We study the variations in speckle size on optical phantoms with different density of scatterers. Phantoms are fabricated with a new approach by introducing silica microspheres in a curing silicon matrix, providing phantoms with a controlled density of scatterers. These phantoms are also solid, deformable, and conservable. Experimental results are obtained with Time-Domain OCT (TD-OCT). Modeling is performed by simulating a phantom as a random distribution with of discrete scatterers. Both experimental results and modeling show that the speckle size varies when there are few scatterers contained within the probed volume, the latter being defined by the coherence length and the spot size of the focusing optics. As a criterion to differentiate tissues, the speckle size has the same sensitivity as the contrast parameter that is studied in Ref. 1. This work also contributes to a better understanding of speckle in OCT.