Scanning Interferometer Aimed at Characterizing Laser Coherence Lengths

Interference fringes generated by superposed beams of light offer one of the most striking and useful applications of wave mechanics in modern society. Utility is limited, however, by the fact that fringes, as generated by overlapping a given laser beam upon itself, can only be observed on length scales shorter than the laser beam’s coherence length. Unfortunately, the coherence lengths of many commonly available light sources, like inexpensive diode lasers and laser pointers, are often not reported. Here we summarize progress on an experiment aimed at characterizing these properties systematically. Results are expected to be relevant to the construction of low-cost interferometric devices [1] that may in turn be of use in pedagogical contexts and industry.

[1] T. M. Melody, et al., Am. J. Phys. 91, 132-141 (2023)