Rapid scanning all-reflective optical delay line for real-time optical coherence tomography.

We describe a dispersion-free high-speed scanning optical delay line that is suitable for real-time optical coherence tomography, in particular, when an ultrabroadband light source is used. The delay line is based on all-reflective optics consisting of two flat and one curved mirrors. We achieve optical path-length scanning by oscillating one of the two flat mirrors with a resonant galvanometer. The delay line is compact and easy to implement. A total scanning depth of 1.50 mm with an 89% duty ratio, a maximal scanning speed of approximately 9.1 m/s, and a 4.1-kHz repetition rate has been demonstrated.