In vivo video-rate cellular-level full-field optical coherence tomography

Full-field optical coherence tomography (FF-OCT) capable of in vivo cellular-level imaging is demonstrated for nonscanning horizontal cross-sectional imaging. The system is based on a white light interference microscope illuminated by a thermal light source. A dual-channel two-dimensional (2-D) detection technique incorporated with a pair of CCD cameras has been developed, where a pair of interferometric images with phase difference of pi/2 are simultaneously captured using an achromatic phase shifter. By acquiring an additional pair of images with a conventional phase shift method, a horizontal cross section is derived from every two consecutive CCD frames, enabling OCT imaging at the video rate. Using an ultrabroad bandwidth illumination incorporated with relatively high NA (0.8 NA) water immersion objectives, an axial resolution of 0.8 microm and a transverse resolution of 0.7 microm are experimentally confirmed. A field of view of 215 microm x 215 microm is covered by the 500 x 500 pixel CCD cameras. We demonstrate, for what is believed to be the first time, in vivo cellular-level blood flow imaging of a Xenopus laevis tadpole by FF-OCT.