Full-field optical coherence tomography at 800 nm and 1300 nm simultaneously

Abstract

Optical coherence tomography (OCT) is a technique of choice for micrometer-scale resolution imaging of biological specimens [1,2]. Full-field optical coherence tomography (FF-OCT) was introduced a few years ago as an alternative method to conventional OCT. FF-OCT is based on an interference microscope with a camera as an array detector combined with a low coherence illumination source for parallel acquisition of en-face oriented tomographic images [3- 5]. FF-OCT is a technique of choice for noninvasive three-dimensional imaging of ex vivo biological tissues with ultrahigh spatial resolution (~ 1 μm) [6,7]. FF-OCT is based on phase-shifting interferometry: several interferometric images are acquired with an image sensor, a phase-shift being introduced between each of these frames by using, for example, the displacement of the reference mirror. The amplitude of the interference signal, i.e. the fringe envelope, is calculated by combination of these frames [8-11]. Recent developments in OCT technology have been carried out in order to exploit the spectroscopic response of the imaged sample. This technique, referred to as spectroscopic OCT, detects and processes the interferometric signal to provide spatially-resolved spectroscopic information. It can be used to enhance image contrast, permitting better differentiation of tissues through their spectroscopic properties and providing additional information on the sample composition [12-14]. An alternative method to take advantage of the spectroscopic response of the sample is to image at several distinct wavelengths. This can be achieved by using several detectors [15,16] or several illumination sources. Spectroscopic imaging with FF-OCT, using several detectors, is demonstrated in this paper.