Low-Coherence Interference Microscopy

Abstract

Confocal microscopy is a powerful technique that permits three-dimensional (3D) imaging of thick objects. Recently, however, two new techniques have been introduced, which are rivals for 3D imaging in reflection mode. Coherence probe microscopy (CPM) is used for surface inspection and profiling, particularly in the semiconductor device industry [1–10]. Optical coherence tomography (OCT) is used for medical diagnostics, particularly in ophthalmology and dermatology [11,12]. These are both types of low coherence interferometry (LCI), in which coherence gating is used for optical sectioning. LCI has many advantages over the conventional (narrow-band source) interferometric techniques, including the ability to reject strongly light that has undergone scattering outside of a small sample volume, thus allowing precise non-invasive optical probing of dense tissue and other turbid media. LCI can be used to investigate deep, narrow structures. This feature is particularly useful for in-vivo measurement of deep tissue, for example, in transpupilliary imaging of the posterior eye and endoscoping imaging. Another application area of LCI is in optical fibre sensors [13–15].KeywordsOptical Coherence TomographyReference BeamGeometric PhaseMicroscope ObjectiveFringe VisibilityThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.