Stroboscope

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Stroboscope

A stroboscope, also known as a strobe, is an instrument used to make a cyclically moving object appear to be slow-moving, or stationary. The principle is used for the study of rotating

Rotation

A rotation is a movement of an object in a circular motion. A two-dimensional object rotates around a center of rotation. A Three-dimensional space object rotates around a line called an axis....
, reciprocating

Reciprocation

Reciprocation is the action in which a body's displacement returns to its starting location in a given time repeatedly, the velocity over which the displacement occurs with each repetition not necessarily being constant....
, oscillating

Oscillation

Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and Alternating current power....
or vibrating

Vibration

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Encyclopedia

A stroboscope, also known as a strobe, is an instrument used to make a cyclically moving object appear to be slow-moving, or stationary. The principle is used for the study of rotating

Rotation

Reciprocation

Oscillation

Vibration

Vibration refers to mechanical oscillations about an equilibrium point. The oscillations may be periodic function such as the motion of a pendulum or random such as the movement of a tire on a gravel road....
objects. Machine parts and vibrating strings are common examples.

In its simplest form, a rotating disc with evenly-spaced holes is placed in the line of sight between the observer and the moving object. The rotational speed of the disc is adjusted so that it becomes synchronised with the movement of the observed system, which seems to slow and stop. The illusion is caused by temporal aliasing

Temporal aliasing

Temporal aliasing is the term applied to a visual phenomenon also known as the stroboscopic effect. It also accounts for the "wagon-wheel effect", so called because in video or motion pictures, spoked wheels on horse-drawn wagons sometimes appear to be turning backwards....
, commonly known as the "stroboscopic effect".

In electronic

Electronics

Electronics refers to the flow of charge through nonmetal electrical conductor , whereas electrical refers to the flow of charge through metal electrical conductor....
versions, the perforated disc is replaced by a lamp

Strobe light

Strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope....
capable of emitting brief and rapid flashes of light. The frequency

Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency....
of the flash is adjusted so that it is a equal to, or a unit fraction

Unit fraction

A unit fraction is a rational number written as a vulgar fraction where the numerator is 1 and the denominator is a positive integer. A unit fraction is therefore the Reciprocal of a positive integer, 1/n....
below or above the object's cyclic speed, at which point the object is seen to be either stationary or moving backward or forward, depending on the flash frequency.

History

Joseph Plateau

Joseph Antoine Ferdinand Plateau was a Belgium physicist.Born in Brussels, he studied at the University of Li?ge , where he graduated as a doctor of physical and mathematical sciences in 1829....
of Belgium

Belgium

* A small German-speaking Community of Belgium exists in eastern Wallonia. Belgium's linguistic diversity and related political and cultural conflicts are reflected in the history of Belgium and a complex Communities and regions of Belgium....
is generally credited with the invention of the stroboscope in 1832, when he used a disc with radial slits which he turned while viewing images on a separate rotating wheel. Plateau called his device the "Phenakistoscope

Phenakistoscope

The phenakistoscope was an early animation device, the predecessor of the zoetrope. It was invented in 1831 simultaneously by the Belgium Joseph Plateau and the Austrian Simon von Stampfer....
". There was a simultaneous and independent invention of the device by the Austria

Austria

Austria , officially the Republic of Austria , is a landlocked country in Central Europe. It borders both Germany and the Czech Republic to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the west....
n Simon von Stampfer, which he named the "Stroboscope", and it is his term which is used today. The etymology is from the Greek words strobo(s), meaning "whirling" and scope meaning "to look at".

As well as having important applications for scientific research, the earliest inventions received immediate popular success as methods for producing moving pictures

Film

Film encompasses individual motion pictures, the field of film as an art form, and the film industry. Films are produced by recording images from the world with cameras, or by creating images using animation techniques or special effects....
, and the principle was used for numerous toys.

Other early pioneers employed rotating or vibrating mirrors. The electronic strobe light

Strobe light

Strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope....
stroboscope was invented in 1931, when Harold Eugene Edgerton

Harold Eugene Edgerton

Harold Eugene "Doc" Edgerton was a professor of electrical engineering at the Massachusetts Institute of Technology. He is largely credited with transforming the stroboscope from an obscure laboratory instrument into a common device....
("Doc" Edgerton) employed a flashing lamp to study machine parts in motion. General Radio

General Radio

General Radio Corporation was a broad-line manufacturer of electronic test equipment. Started in Cambridge, Massachusetts in 1915, the company moved to Concord, Massachusetts in the 1950s....
Corporation then went on to productize this invention in the form of their "Strobotach".

Edgerton later used very short flashes of light as a means of producing still photographs

Photography

Photography is the process, activity and art of creating still or moving by recording radiation on a sensitive medium, such as a photographic film, or an ....
of fast-moving objects, such as bullets in flight.

Applications

Stroboscopes play an important role in the study of stresses on machinery in motion, and in many other forms of research. They are also used as measuring instruments for determining cyclic speed.

As a timing light

Timing light

A timing light is a stroboscope used to dynamically set the ignition timing of an Otto cycle or similar internal combustion engine.The timing light is connected to the ignition circuit and used to illuminate the timing marks with the engine running....
they are used to set the ignition

Ignition system

An ignition system is a system for igniting a fuel-air mixture. It is best known in the field of internal combustion engines but also has other applications, e.g....
timing

Timing

Timing is the spacing of events in time. Some typical uses are:* The act of measuring the elapsed time of something or someone, often at athletic events such as swimming or running, where participants are timed with a device such as a stopwatch....
of internal combustion engine

Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs in a combustion chamber inside and integral to the engine. In an internal combustion engine it is always the expansion of the high temperature and pressure gases that are produced by the combustion which apply force to the movable component of the engine, such as...
s.

In medicine, stroboscopes are used to view the vocal cords for diagnosis. The patient hums or speaks into a microphone

Microphone

A microphone, sometimes referred to as a mike or?more recently?mic, is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal....
which in turn activates the stroboscope at either the same or a slightly different frequency. The light source and a camera are positioned by endoscopy.

Another application of the stroboscope can be seen on many gramophone

Gramophone

Gramophone might refer to:* The British English term for U.S. English "phonograph", the first device for recording and replaying sound. The two names were originally those used by rival manufacturers...
turntables. The edge of the platter has marks at specific intervals so that when viewed under fluorescent lighting powered at mains frequency, provided the platter is rotating at the correct speed, the marks appear to be stationary. This will not work under incandescent lighting

Incandescent light bulb

The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric light that works by incandescence, ....
, as incandescent bulbs don't strobe. For this reason, some turntables have a neon bulb next to the platter.

Flashing lamp

Strobe light

Strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope....
strobes are also adapted for pop use, as a lighting effect for discotheque

Discothèque

A discoth?que, , is an entertainment venue or club with music record played by "Discaires" through a PA system, rather than an Live band dance....
s and night clubs where they give the impression of dancing in slow motion.

Other effects

Rapid flashing can give the illusion that white light is tinged with colour, known as Fechner colour

Fechner color

Fechner color is an illusion of color seen when looking at certain rapidly changing or moving black-and-white patterns. They are also called pattern induced flicker colors ....
. Within certain ranges, the apparent colour can be controlled by the frequency of the flash, but it is an illusion generated in the mind of the observer and not a real colour. The Benham's top

Benham's top

Benham's top, also called Benham's disk, is named after the English toymaker Charles Benham, who, in 1895, sold a top painted with the pattern shown at right....
demonstrates the effect.

At certain frequencies, flashing light can trigger epileptic seizures

Photosensitive epilepsy

Photosensitive epilepsy is a form of epilepsy in which seizures are triggered by visual stimuli that form patterns in time or space, such as flashing lights, bold, regular patterns, or regular moving patterns....
in some people.

Stroboscope

History

Applications

Other effects

See also

External links