An evaluation procedure for scanning interferometer based wavemeters

Abstract A common approach to wavelength measurement is the travelling interferometer (wavemeter). We present an evaluation procedure that allows to achieve high precision with a compact device. The zero crossings of the interference signal corresponding to the reference laser is used to sample the signal of the probe laser. Electronic noise and fluctuations of the laser frequency cancel due to the large number of sample points. The evaluation procedure has been applied to a wavemeter based on a continuously moving Mach–Zehnder interferometer. A travelling path of 10 cm was sufficient to yield 3σ-accuracy of Δ λ / λ =3.2×10 −9 , demonstrated by comparison with cesium saturation spectroscopy.