Long-optical-path scanning mechanism for optical coherence tomography

A new scanning mechanism for a long optical path change in an interferometer is proposed. It consists of corner reflectors, arranged on a rotating disk at regular intervals, and an outer mirror. A reference beam in the interferometer is reflected on the corner reflector and the mirror, and then comes back to the same way whenever the reflector moves along to the disk rotation. This action makes it possible to obtain a long path change with nearly linear motion. An optical path length change, a scanning speed, and a repetition rate can be designed suitably. The rotating disk of the diameter 120mm gives the optical path change of more than 40mm. The deviation of the optical path change against the linear motion is less than 0.3%. An optical coherence tomography system with the proposed long path optical scanner has been developed and evaluated the motion characteristics. With the disk size mentioned above, the maximum repetition rate was designed as 15scans/s at the disk rotation of 60rpm. We have demonstrated the fundamental experiment of samples such as stacked slide glasses and a mirror separated from a slide glass. The experiment was in good agreement with the prediction.