We present an improved time-domain optical coherence tomography technique designed for ultrahigh-resolution B-scan imaging in real-time. The technique, called line-field confocal optical coherence tomography, is based on a Linnik-type interference microscope with line illumination using a supercontinuum laser and line detection using a line-scan camera. Bscan imaging with dynamic focusing is achieved by acquiring multiple A-scans in parallel. In vivo cellular level resolution imaging of skin is demonstrated at 10 frame/s with a penetration depth of ∼ 500 μm, with a spatial resolution of 1.3 μm × 1.1 μm (transverse × axial).
This work reports on a compact full-field optical coherence microscopy (FF-OCM) setup specifically designed to meet
the needs for in vivo imaging, illuminated by a high-brightness broadband light emitting diode (LED). Broadband LEDs
have spectra potentially large enough to provide imaging spatial resolutions similar to those reached using conventional
halogen lamps, but their radiance can be much higher, which leads to high speed acquisition and makes in vivo imaging
possible. We introduce a FF-OCM setup using a 2.3 W broadband LED, with an interferometer designed to be as
compact as possible in order to provide the basis for a portable system that will make it possible to fully benefit from the
capacity for in vivo imaging by providing the ability to image any region of interest in real-time. The interferometer part
of the compact FF-OCM setup weighs 210 g for a size of 11x11x5 cm<sup>3</sup>. Using this setup, a sub-micron axial resolution
was reached, with a detection sensitivity of 68 dB at an imaging rate of 250 Hz. Due to the high imaging rate, the
sensitivity could be improved by accumulation while maintaining an acquisition time short enough for in vivo imaging. It
was possible to reach a sensitivity of 75 dB at a 50 Hz imaging rate. High resolution in vivo human skin images were
obtained with this setup and compared with images of excised human skin, showing high similarity.
This work reports on the feasibility of dynamic imaging using conventional reflectivity-based tomographic images
obtained with full-field optical coherence microscopy (FF-OCM). Implementation of speckle variance for flow mapping
with an imaging rate of 180 Hz is demonstrated by mapping 20% intralipid flowing into 100-μm-diameter microcapillary
tubes at speeds up to ~ 50 mm/s. This constitutes a significant advance in high-resolution, real-time microvasculature
mapping, using FF-OCM. The acquisition scheme in FF-OCM is particularly appropriate for en face visualization of the
microvasculature, as FF-OCM directly acquires en face tomographic images unlike conventional OCT which usually
requires reslicing of a three-dimensional data set to get en face images.