An optical chopper is a mechanical device which periodically interrupts a light beam. Three types are available: variable frequency rotating disc choppers, fixed frequency tuning fork choppers, and optical shutters. A rotating disc chopper was famously used in 1849 by Hippolyte Fizeau in the first non-astronomical measurement of the speed of light.

External links

• Explanation of optical choppers from Scitec Instruments, which is a specialist manufacturer of rotating disc optical choppers
• Boston Electronics, a major vendor.

Other optical chopper vendors include Electro-Optical Products Corporation(a manufacturer of tuning fork choppers), New Focus, Terahertz Technologies, SRS, Ametekand Photon Technology International.

Optical metrology