An assembly includes an etalon assembly for dynamically locking a frequency of an optical beam to a set frequency, the etalon assembly being external to a laser source assembly that outputs the optical beam. The etalon assembly includes an etalon that receives the optical beam and generates via interference effects a transmission beam, the etalon having a thermal tuning range greater than one half of a free spectral range of the etalon. The etalon assembly also includes an etalon heater mounted to the etalon such that the etalon heater is configured to adjust the temperature of the etalon. The assembly includes a controller configured to retrieve calibration data based on the set frequency, calculate a set temperature for the etalon using a thermal tuning algorithm and the calibration data, and control the etalon heater such that the etalon has a temperature equal to the calculated set temperature.