Optical chopper
Encyclopedia
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
.
"The chopper amplifier allows for either a physical quantity to be measured or on the electrical signal from the transducer. In general it is desirable to chop the signal as close to its source as possible because only the noise that arises after chopping is removed by the process. The rotation of the chopper produces a radiant signal that fluctuates periodically between zero and some maximum intensity."
There are also electrical ways of generating pulsed light beams at a variable millisecond intervals. As an electrical alternative to the rotating disc, pulsed light is currently used to grow plants under intermittent artificial light generated using specially designed ballast systems for standard fluorescent light tubes. Because the light beam is interrupted before the light is generated, unlike devices which interrupt the light after it is generated, the electrically pulsed light tubes reduce the energy requirements of pulsed light applications by an amount equal to the percentage of pulsing, so a 50% flickered on-off light stream is made with 50% less energy. “Chopper Light” systems are also suitable for UV applications.
Late 20th century computer mice used two chopper wheels for encoding.
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
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
Hippolyte Fizeau
Armand Hippolyte Louis Fizeau was a French physicist.-Biography:Fizeau was born in Paris. His earliest work was concerned with improvements in photographic processes. Following suggestions by François Arago, Léon Foucault and Fizeau collaborated in a series of investigations on the interference of...
in the first non-astronomical measurement of the speed of light
Speed of light
The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...
.
"The chopper amplifier allows for either a physical quantity to be measured or on the electrical signal from the transducer. In general it is desirable to chop the signal as close to its source as possible because only the noise that arises after chopping is removed by the process. The rotation of the chopper produces a radiant signal that fluctuates periodically between zero and some maximum intensity."
There are also electrical ways of generating pulsed light beams at a variable millisecond intervals. As an electrical alternative to the rotating disc, pulsed light is currently used to grow plants under intermittent artificial light generated using specially designed ballast systems for standard fluorescent light tubes. Because the light beam is interrupted before the light is generated, unlike devices which interrupt the light after it is generated, the electrically pulsed light tubes reduce the energy requirements of pulsed light applications by an amount equal to the percentage of pulsing, so a 50% flickered on-off light stream is made with 50% less energy. “Chopper Light” systems are also suitable for UV applications.
Late 20th century computer mice used two chopper wheels for encoding.