An interferometer for characterizing a sample, the interferometer including a light emitter to produce a light beam. A wavelength modulator can dither a wavelength of the light beam to produce an input beam having an oscillating wavelength. A beam splitter can be configured to divide the input beam into a reference beam and a measurement beam. The reference beam can reflect from a mirror having a fixed position and return to the beam splitter. The measurement beam can reflect from the sample and return to the beam splitter. The beam splitter can interfere the received reference beam and measurement beam to form an output beam. A detector can convert the output beam to an electrical signal. A processor can control the wavelength modulator, receive the electrical signal, and determine a distance to the sample based on the electrical signal and the oscillating wavelength of the input beam.