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 $38 \mu \mathrm{m}$ and transverse resolution of at least $12.7 \mu \mathrm{m}$. The technique is readily adaptable to endoscopic delivery as well as three-dimensional real-time image acquisition.