Basic Principles

        The principle OCT is white light or low coherence interferometry. The optical setup typically consists of an

        interferometer with a low coherence, broad bandwidth light  

        source. Light is split into and recombined from reference and

        sample arm, respectively.

        In time domain OCT the pathlength of the reference arm is

        translated longitudinally in time. The interference of two

        partially coherent light beams can be expressed as

        In frequency domain OCT the broadband intereference is acquired with spectrally separated detectors (either by

        encoding the optical frequency in time with a spectrally scanning source or with a dispersive detector, like a

        grating and a linear detector array).

         Focusing the light beam to a point on the surface of the sample under test, and recombining the reflected light

         with the reference will yield an interferogram with sample information corresponding to a single A-scan (Z axis

         only). Scanning of the sample can be accomplished by either scanning the light on the sample, or by moving

         the sample under test.

Designed by Jingjing Jiang