Abstract: A micromachined interferometer is achieved using a half plane beam splitter. The beam splitter is optically coupled to receive an incident beam and operates to split the incident beam into two interfering beams, each propagating in a different medium. A fixed mirror embedded in one of the mediums reflects one of the interfering beams back towards the half plane beam splitter through such medium, while a moveable mirror, which is controlled by an actuator, reflects the other interfering beam back towards said half plane beam splitter through the other medium. A detection plane detects an interference pattern produced as a result of interference between the reflected interfering beams.