Abstract: A method and apparatus for high-resolution interferometry and high-resolution spectrometry. The apparatus includes a beam splitter, at least one test path reflector, a fixed reflector mount, a movable reflector mount with at least one test path reflector thereon, a reference return reflector, a test return reflector on either the fixed reflector mount or the movable reflector mount, and a sensor. A beam of light hitting the beam splitter is split into a test beam and a reference beam. The test beam is directed towards the test return reflector via the test path reflectors, then is reflected by the test return reflector back to the beam splitter by the same path. The beam splitter directs part of the test beam to the sensor. The reference beam is directed towards the reference return reflector, which reflects it back to the beam splitter. The beam splitter directs part of the reference beam to the sensor. At the sensor, the test and reference beams interfere.