Fabry Perot Interferometer OE-7025



A Fabry Perot Interferometer is an optical interferometer in which a beam of light undergoes multiple reflections between two reflecting surfaces and its resulting optical transmission (or reflection) is periodic in wavelength. The Fabry – Perot design contains plane surfaces that are partially reflecting so that multiple rays of light are responsible for the creation of the observed interference patterns. For high resolution spectroscopy, where a resolution in the range of MHz to GHz is required, a Fabry – Perot interferometer (FP) is used.

In Fabry – Perot interferometer, the distance between the partially reflecting mirrors are varied by using coarse and finely adjustable translation stage driven by micro-meters. One mirror is fixed and the other is mounted on the translation stage through a kinematic mount. This two axis kinematic mount is used to correct the parallelism between beam splitter.


Experiment Performed

  • To find wavelength of laser source.
  • To find the Spacing between two mirrors by using fringes.
  • To find the Finesse and Free Spectral Range of the Etalon.



  • Precision design of optical components
  • Well polished Mirrors
  • Easy to operate
  • Extended durability
  • Corrosion free mechanical assembly


Experimental set up Contain Quantity
Optical rail with stands Length 1000mm

Fabry  Perot Interferometer (Spacing of plates 4+/- 1 mm)

Convex lens with mount(f = 100mm)

Diode laser < 5mW (650nm or 532nm)

Diode laser power supply

Diffuser screen with measurement unit

White screen(Acrylic)

Kinematic laser mount