Holmarc’s Fabry-Perot etalon is made of plate beam splitters separated by a distance. The beam splitters are made by coating aluminium thin films on optically polished N-BK7 substrate. The reflecting surfaces are kept inside in assembly. The etalon has optical resonator properties similar to that of laser.

The apparatus consists of diode laser, etalon , lens and screen assembled on a rail and carriage system. Laser head is mounted using a kinematic holder while lens is held in position using a rigid mount. As all modules are mounted using rail carriages, distance between each modules can be adjusted conveniently. All components are made out of aluminium and stainless steel for corrosion free life. The etalon is made from research quality optics.

The Fabry-Perot etalon is operated by multiple beam interference as shown in the schematic diagram. Light which incident on the etalon is split in to a series of parallel transmitted rays by multiple reflections. Note that the ray is partially transmitted at each reflection from the second surface.