Speckle noise is one of the dominant factors that degrade image quality in optical coherence tomography (OCT). Here, we propose a new strategy, interleaved OCT (iOCT), for spatial compounding and angular compounding. We demonstrate the efficiency of compounding with iOCT to restrain speckle noise without compromising imaging speed in phantoms and tissue samples.
We demonstrate a cross-dispersed spectrometer for Spectral Domain Optical Coherence Tomography (SD-OCT). The resolution of a conventional SD-OCT spectrometer is limited by the available sizes of the linear array detectors. The adverse consequences of this finite resolution is a trade-off between achieving practical field of view (i.e. ranging depth) and maintaining high axial resolution. Inspired by spectrometer designs for astronomy, we take advantage of very high pixel-density 2D CCD arrays to map a single-shot 2D spectrum to an OCT A-scan. The basic system can be implemented using a high-resolution Echelle grating crossed with a prism in a direction orthogonal to the dispersion axis. In this geometry, the interferometric light returning from the OCT system is dispersed in two dimensions; the resulting spectrum can achieve more pixels than a traditional OCT spectrometer (which increases the ranging depth) and maintains impressive axial resolution because of the broad bandwidth of the detected OCT light. To the best of our knowledge, we present the first demonstration of OCT data using an Echelle-based cross-dispersed spectrometer. Potential applications for such a system include high-resolution imaging of the retina or the anterior segment of the eye over extended imaging depths and small animal imaging.
We describe a novel spectrometer design for spectral-domain optical coherence tomography (OCT) that enables singleshot inter-pixel shifting (IPS) for extended ranging depth. Compared to other methods of IPS, oblique incidence spectroscopy exploits the high pixel density of 2D cameras to permit sub-pixel-sized sampling of the OCT interferogram during acquisition of a single camera frame. Limited ultimately by fall-off and the pixel size, we demonstrate recovery of signal from samples positioned as deep as four times the base ranging depth of an equivalent traditional spectrometer. We also show for the first time, to the best of our knowledge, the ability to generate arbitrary ranging depths with SDOCT, including non-integer multiples of the base ranging depth.