Long-Optical-Path Scanning Mechanism for Optical Coherence Tomography

A new scanning mechanism for changing long optical paths is proposed. This mechanism consists of corner reflectors arranged equally upon a disk and an outer mirror. Rotating the 120-mm (phi) disk cases a long-opticalpath change in each reflector with a near linearity of more than 40 mm. An optical coherence tomography system is described that confirms the usefulness of the proposed mechanism. Its operating characteristics and accuracy are evaluated by analysis and experiment. The deviation of the optical-path change is less than 1.52% at a reflector rotation angle of +-10 (degree). A high-speed lock-in amplifier is utilized for fundamental measurements of glass samples.