A reliable, compact and low-cost Michelson wavemeter for laser wavelength measurement

We describe the construction and operation of a simple, compact, and cost effective Michelson wavemeter with picometer accuracy. The low cost of the device means that it can form the basis of an undergraduate laboratory experiment, yet it is sufficiently reliable and accurate that it has become an important tool in our research laboratory, where it is regularly used to tune lasers to atomic transitions. The usefulness and accuracy of the wavemeter is demonstrated by tuning two separate extended cavity diode lasers to achieve two-step excitation of the Rb [5.sup.2]D state, observed by detecting 420 nm blue fluorescence from the [5.sup.2]D [approaches] [6.sup.2]P [approaches] [5.sup.2]S decay path.