Spatially resolved spectral interferometry for determination of subsurface structure.

We describe an instrument capable of obtaining two-dimensional images of subsurface structure in real time with no moving parts. The technique is based on spectral interferometry and uses an imaging spectrograph to obtain spatially resolved spectra. A test sample consisting of microscope coverslips and a Ronchi grating was measured, illustrating the system's depth resolution of 38 mum and transverse resolution of at least 12.7 mum . The technique is readily adaptable to endoscopic delivery as well as three-dimensional real-time image acquisition.