Confocal laser feedback microscopy for in-depth imaging applications

We propose confocal laser feedback microscopy for in-depth imaging of highly scattering samples. This technique provides a compact configuration for microscopy in reflectance mode; it is based on laser feedback interferometry which is a sensing technique where the laser acts as both transmitter and receiver of the beam. Operating at 850 nm, it offers an ideal platform for non-invasive and in vivo imaging of soft biological tissues. To explore the technique, the authors performed microscopic imaging of micro-glass-spheres (with diameter sizes of 10–20 µm) deep within an agar gel sample, at depth of 0.43 mm from the surface. Experimental results show the feasibility of a compact, low-cost, and simple laser-scanning microscope with possible biomedical imaging applications.