Quasi-simultaneous optical coherence tomography and confocal imaging

A new approach of acquiring quasi-simultaneous optical coherence tomography (OCT) and confocal images is presented. The two images are generated using different principles, OCT and confocal microscopy. When the system is used to image the retina, the two images have depth resolutions, at present, of <20 microm and approximately 1 mm, respectively. The acquisition and display of en face OCT and confocal images are quasi-simultaneous, without the need of a beamsplitter. By using a chopper to periodically obstruct the reference beam in the OCT interferometer, synchronized with the XY-transversal scanner, much higher acquisition speed is obtained than in a previous report where we flipped an opaque screen in the reference arm of the interferometer. Successful operation of the novel configuration was achieved by: (1) stable synchronization of the chopper's movement with the horizontal line scanner and (2) fast self-adjusting of the gain value of avalanche photodiodes, depending on the optical power. Images from coin, leaves, and retina in vivo have been collected to demonstrate the functionality of the system.