Abstract

Optical coherence microscopy¹ (OCM) is a novel technique complementary to optical coherence tomography^2,3 (OCT), which combines low-coherence interferometry with confocal microscopy to achieve micron-resolution optical imaging deep in highly scattering media. OCM can be implemented using a single-mode fiber optic low-coherence interferometer (see Fig. 1). A high numerical aperture objective is used to focus sample arm light into the specimen under examination, and the reference arm length is adjusted to match the sample arm focal plane optical depth. The sample arm of the interferometer comprises a scanning confocal microscope, in which either the sample or the probe beam is laterally scanned in a raster pattern and the optical fiber acts as a single-mode confocal aperture for illumination and collection. The axial point-spread function of the OCM is given by the product of the point-spread functions of the objective and the low-coherence interferometer, the latter of which (the "coherence gate") is very close to a Gaussian function for a superluminescent diode source.¹ With sufficiently high numerical aperture focusing, the point-spread function is dominated near the focus by the microscope objective, while far from the focus the coherence gate strongly rejects scattered light incompletely eliminated by the wings of the confocal microscope point-spread function (Fig. 2), Initial studies of OCM in model scattering media¹ have demonstrated that this technique provides improved optical sectioning depth in highly scattering tissues as compared to confocal microscopy. OCM thus has potential for applications in ín sítu dísease diagnosis in high-magnification endoscopy, or as an adjunct to conventional histopathologic techniques.

© 1996 Optical Society of America