Digital holoscopy

Abstract

Optical coherence tomography (OCT) images three-dimensional biological tissues with micrometer resolution. While time–domain OCT required axial scanning of the imaging plane or the specimen, Fourier–domain OCT enabled parallel detection of all depths, which allowed to increase the acquisition speed by several orders of magnitude. When increasing the numerical aperture (NA) for achieving microscopic resolution, the advantage of Fourier–domain over time–domain OCT is lost. The resolution and sensitivity of FD–OCT degrade outside of the focal region. By a consequent combination of digital holography with full–field swept–source OCT, which was implemented by holoscopy, tomographic images are obtained with optimal sensitivity and resolution spanning regions much larger than the focal range. Using this technique image quality was comparable to full–field swept–source OCT. Current implementations of holoscopy face many challenges: reduced image quality caused by artifacts, incoherent background and multiple scattered photons, and lack of affordable cameras and suitable tunable light sources. If these problems are solved, higher sensitivity and acquisition speed will make holoscopy a useful alternative to other OCT techniques.