Coherent microscopy by laser optical feedback imaging (LOFI) technique

The application of the non-conventional imaging technique LOFI (laser optical feedback imaging) to coherent microscopy is presented. This simple and efficient technique using frequency-shifted optical feedback needs the sample to be scanned in order to obtain an image. The effects on magnitude and phase signals such as vignetting and field curvature occasioned by the scanning with galvanometric mirrors are discussed. A simple monitoring method based on phase images is proposed to find the optimal position of the scanner. Finally, some experimental results illustrating this technique are presented. ► Laser optical feedback imaging (LOFI) is a novel technique for coherent microscopy. ► Galvanometric scanner induces some distortions of magnitude and phase images. ► Phase monitoring is an efficient method for scanner positioning optimization. ► LOFI imagery offers complementary information compared to standard techniques.