Using low-finess etalons and Bayer filters for low cost yet robust laser wavelength metrology

Measuring the wavelength of a laser precisely is critical in multiple fields such as atomic spectroscopy, precision navigation, and even in gravitational wave detection. Here, we present a wavelength meter with picometer resolution based on etaloning effects of inexpensive glass slides and the built-in color filters of a low-cost CMOS camera. We demonstrate that after calibration with a standard commercial wavemeter, the device is accurate for over 16 days by regular testing with two tunable lasers. We determined the device's error is only 0.04 parts per million (ppm) within the first 24 hours and only increases to 0.90 ppm with a standard deviation of 5.29 ppm over a period of 16 days.