Optical chopper
![An assortment of chopper wheels](/Images/godic/202501/31/Chopper_wheels4024.jpg")
![](/Images/godic/202501/31/Seaman_send_Morse_code_signals4024.jpg")
![US Navy sailor sending Morse code using a signal lamp](/Images/godic/202501/31/Mouse_mechanism_diagram.svg4024.png")
An optical chopper is a 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.