Full-field optical coherence tomography (FF-OCT) is a powerful tool for nondestructive
assessment of biological tissue, i.e., for the structural examination of tissue in
depth at a cellular resolution. Mostly known as a microscopy device for ex vivo analysis,
FF-OCT has also been adapted to endoscopy setups since it shows good potential for
in situ cancer diagnosis and biopsy guidance. Nevertheless, all the attempts to perform
endoscopic FF-OCT imaging did not go beyond lab setups. We describe here, to the best
of our knowledge, the first handheld FF-OCT endoscope based on a tandem interferometry
assembly using incoherent illumination. A common-path passive imaging interferometer
at the tip of an optical probe makes it robust and insensitive to environmental perturbations,
and a low finesse Fabry-Perot processing interferometer guarantees a compact system.
A good resolution (2.7 μm transverse and 6 μm axial) is maintained through the long
distance, small diameter relay optics of the probe, and a good signal-to-noise ratio
is achieved in a limited 100 ms acquisition time. High-resolution images and a movie
of a rat brain slice have been recorded by moving the contact endoscope over the surface
of the sample, allowing for tissue microscopic exploration at 20 m under the surface.
These promising ex vivo results open new perspectives for in vivo imaging of biological
tissue, in particular, in the field of cancer and surgical margin assessment.