Simple Electrical Modulation Scheme for Laser Feedback Imaging

In this paper, we demonstrate a simple square-wave electrical modulation scheme for imaging with laser feedback interferometry (LFI). Distinct advantages of this scheme include: 1) the straightforward creation of the modulating signal, even for high-current lasers and 2) its natural suitability for lock-in detection. We compare this simple scheme against two established imaging modalities for LFI: 1) mechanical modulation using an optical chopper and 2) the swept-frequency feedback interferometry approach. The proposed scheme lends itself to high-frequency modulation, which paves the way for high frame-rate LFI imaging with no motion artefacts using off-the-shelf equipment.