A stroboscope also known as strobe , is an instrument used to create moving objects on a slow-moving, or stationary-looking, cycle. It consists of rotating disks with slots or holes or lights such as flashtube that produce repeated short flashes of light. Usually the stroboscope rate is adjusted to different frequencies. When a rotating or vibrating object is observed with a stroboscope at its vibration frequency (or submultiple from it), it appears silent. So the stroboscope is also used to measure the frequency.
This principle is used to study objects that rotate, vibrate, oscillate or vibrate. The engine part and the vibrating string are common examples. A stroboscope used to adjust the ignition timing of an internal combustion engine is called a time lamp.
Video Stroboscope
Type
Mechanical
In the simplest mechanical form, a rotating cylinder (or a raised raised bowl) with a hole or slot placed evenly across the line of sight between the observer and the moving object. The observer sees through the hole/slot on the near and far side at the same time, with the slot/hole moving in the opposite direction. When the hole/slot is aligned on the opposite side, the object is seen by the observer.
Alternately, a single hole or moving slot can be used with fixed/stationary holes/slots. The stationary or slot hole limits the light to a single point of view and reduces the glare from light passing through other parts of the moving hole/slot.
Looking through a single row of holes/slots does not work, because the hole/slot looks just sweeping the whole object without the strobe effect.
The rotation speed is adjusted so that it becomes synchronized with the observed system movement, which seems to slow down and stop. This illusion is caused by temporal aliasing, commonly known as the stroboscopic effect.
Electronics
In the electronic version, the perforated disks are replaced with lights capable of emitting short, quick flashes of light. Usually a gas-discharge or solid-state lamp is used, as they are able to emit light almost instantaneously when power is applied, and extinguish just as quickly when power is removed.
For comparison, incandescent lamps have brief heating when energized, followed by a cooling period when electricity is discharged. This delay causes smudged and blurred object details that are partially illuminated during periods of heating and cooling. For most applications, incandescent lights are too slow for a clear stroboscopic effect. However when operated from their AC source it is mostly fast enough to cause audible buzzing (on multiple electrical frequencies) on optical audio playback as on film projection.
The flash frequency is adjusted so that it is equal to, or the unit fraction of the cyclic speed of the object, at which point the object looks to be stationary or moves slowly backwards or forwards, depending on the flash frequency.
Fluorescent lights or light-emitting diodes are commonly used for low intensity strobe applications, the Neon lamp is more common before the development of solid-state electronics, but is replaced by LEDs in most low intensity strobe applications.
Xenon flash lights are used for medium and high intensity strobe applications. Lightning fast enough or bright may require active cooling such as cooling air or water to prevent the xenon flash from melting.
Maps Stroboscope
History
Joseph Plateau of Belgium is generally credited with the invention of the stroboscope in 1832, when he used a disc with a radial slit that he turned when viewing images on a separate spinning wheel. Plateau calls his device "Phenakistoscope". There was a simultaneous and independent discovery of the device by Austrian Simon Ritter von Stampfer, which he named "Stroboscope", and that is the term used today. Etymology comes from the Greek word ??????? - strobos , meaning "whirlpool" and ??????? - skopein , which means "to see".
As well as having important applications for scientific research, the earliest discoveries received popular success soon as a method for producing moving images, and the principle was used for many toys. Other early pioneers used a spinning mirror, or a vibrating mirror known as a mirror galvanometer.
In 1917, French engineer Etienne Oehmichen patented the first electric stroboscope, building at the same time a camera capable of photographing 1,000 frames per second.
Strobe light strobe electronics were invented in 1931, when Harold Eugene Edgerton ("Doc" Edgerton) used flashing lights to study the moving parts of the machine. General Radio Corporation then proceeded to produce this discovery in the form of their "Strobotach".
Edgerton then uses a very short flash of light as a means to produce photographs of fast moving objects, such as bullets in flight.
Apps
Stroboscopes play an important role in the study of pressure on moving machinery, and in many other forms of research. The bright stroboscopes are able to cope with ambient lighting and create a clear stop-motion effect without requiring ambient dark operating conditions.
They are also used as a measuring instrument to determine cyclic speed. As a time light they are used to set the ignition timing of the internal combustion engine.
In the medical world, stroboscopes are used to view the vocal cords for diagnosis of conditions that produce dysphonia (hoarseness). Patients hum or speak into a microphone which in turn activates the stroboscope at the same or slightly different frequencies. Light source and camera positioned by endoscopy.
Other applications of stroboscope can be seen in many turntable gramophones. The edge of the plate has a mark at certain intervals so that when viewed under a fluorescent lamp powered at an electrical frequency, provided that the plates rotate at the correct speed, the signs appear stationary. This will not work well under incandescent bulbs, because incandescent bulbs are not significantly strobe. For this reason, some turntables have neon or LED lights next to the plate. The LED must be driven by a half wave rectifier from the parent transformer, or by an oscillator.
Flash lamps were also adapted for pop use, as a lighting effect for discos and nightclubs where they gave the impression of dancing in slow motion. The strobe level of these devices is usually not very accurate or very fast, because entertainment applications usually do not require high-level performance.
Other effects
Lightning fast can give the illusion that white light is colored with color, known as Fechner's color. In a certain range, the visible color can be controlled by the frequency of the flash, but it is an illusion generated in the mind of the observer and not the real color. The top of Benham shows the effect.
See also
- Electrotachyscope
- Flip Book
- Reciprocating movement
- Phenakistoscope
- Pre-photographic
- Spotlight
- Strobe tuner
- Tachometer
- Thaumatrope
- Zoetrope
References
External links
- Definition of dictionary stroboscope in Wiktionary
- Demonstration of Phenakistoscope and Stroboscope at North Carolina School of Science and Mathematics
Source of the article : Wikipedia
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