Dynamic coherent focus OCT with depth-independent transversal resolution

Abstract

We present a new OCT technique which renders the transversal resolution depth independent. This is achieved by an optical setup which shifts the focus of the beam illuminating the object through the object depth without changing the path length in the corresponding interferometer arm. Therefore, the coherence gate remains at the beam focus without any readjustment of the reference arm. Depth resolution was tested with the help of microscopy cover-plates and transversal resolution was tested with the help of Ronchi rulings. Resolution was 100 lines mm−1 over an object depth of 430 μm. For a first demonstration of the properties of this dynamic coherent focus scheme in a biologic system a section of a human cornea was used. We expect that this technique can further be improved to obtain transversal resolution down to the 1-μm range