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Topic: Mirror galvanometer

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	Galvanometer - LoveToKnow 1911 (Site not responding. Last check: 2007-10-23)
		The magnet had a mirror attached to it, and a telescope having cross wires in the focus was used to observe the scale divisions of a fixed scale seen reflected in the mirror.
		A ray of light being thrown on the mirror from a lamp the deflexions of the needle were observed by watching the movements of a spot of light reflected from it upon a fixed scale.
		In the construction of a movable coil galvanometer, it is usual to intensify the magnetic field by inserting a fixed soft iron core in the interior of the movable coil.
	www.1911encyclopedia.org /Galvanometer (2114 words)

	Galvanometer Summary
		In the case of a moving-mirror galvanometer, a mirror is attached to the coil, and illuminated with light.
		The mirror galvanometer was of major use in laying the transatlantic telegraph cable between the United States and Europe in 1866.
		In some cases (the classical polygraph of movies or the electroencephalograph), the galvanometer is strong enough to move the pen while it remains in contact with the paper; the writing mechanism may be a heated tip on the needle writing on heat-sensitive paper or a fluid-fed pen.
	www.bookrags.com /Galvanometer (1365 words)

	Mirror galvanometer - Wikipedia, the free encyclopedia
		A mirror galvanometer is a mechanical meter that senses electric current, except that instead of moving a needle, it moves a mirror.
		Mirror galvanometers were used extensively in scientific instruments before reliable, stable electronic amplifiers were available.
		A beam of light is thrown from a lamp upon the mirror, and reflected by it upon a white screen or scale a few feet distant, where it forms a bright spot of light.
	en.wikipedia.org /wiki/Mirror_galvanometer (585 words)

	Galvanometer - Wikipedia, the free encyclopedia
		The accuracy of the reading from a mirrored scale is improved by moving the head while reading the scale so that the pointer and the reflection of the pointer are aligned; at this point, the operator's eye must be directly above the pointer and any parallax error has been minimized.
		Galvanometer mechanisms are used to position the pens of analog chart recorders such as used for making an electrocardiogram.
		In some cases (the classical polygraph of movies or the electroencephalograph), the galvanometer is strong enough to move the pen while it remains in contact with the paper; the writing mechanism may be a heated tip on the needle writing on heat-sensitive paper or a fluid-fed pen.
	en.wikipedia.org /wiki/Galvanometer (880 words)

	Galvanometers
		All galvanometers are based upon the discovery by Hans C. Oersted that a magnetic needle is deflected by the presence of an electric current in a nearby conductor.
		These meters were called tangent galvanometers because the tangent of the angle of deflection of the needle is proportional to the strength of the current in the coil (at this point in time it was impossible to construct a meter whose needle deflection was directly proportional to the current under measurement).
		One of the limitations of early galvanometers was that the length of the needle had to be kept very short in order to minimize the effects of the earth's magnetic field and reduce damping errors introduced by the mass of the needle itself.
	www.sparkmuseum.com /GALV.HTM (761 words)

	GALVANOMETER - Online Information article about GALVANOMETER
		By the sensitiveness of the Movable needle galvanometer.
		metre from the mirror, when an electromotive force of one-millionth of a volt (microvolt) is applied to the terminals of the galvanometer; it may be otherwise expressed by stating the deflexion produced under the same conditions when a current of one microampere is passed through the coil.
		swing to the next succeeding swing, and a galvanometer of which the logarithmic decrement is large, is said to be highly damped.
	encyclopedia.jrank.org /GAG_GEO/GALVANOMETER.html (3018 words)

	Multibeam laser drilling apparatus - Patent 6849824
		Provided is a multi-beam laser drilling apparatus for drilling a workpiece, simultaneously at two positions while telecentric errors are suppressed, in which a conventional optical system in which galvanometer mirrors are used for a first laser beam, and a galvanometer-mirror system is located close to an f.theta.
		Thus, the galvanometer mirrors 1a, 1b, 2a, 2b can be located closer to one another, and accordingly, telecentric errors of the f.theta.
		Further, since the galvanometer mirrors can be located closer to one another, the scanning width of the second laser beam 10 can be decreased on the galvanometer mirrors 1a, 1b, and accordingly, the sizes of the galvanometer mirrors 1a, 1b can be decreased.
	www.freepatentsonline.com /6849824.html (3072 words)

	United States Patent Application: 0030174120
		The vertical shifting device 27 may be an electrically driven galvanometer mirror or a manually (mechanically) driven mirror that rotates on an axis to shift the position of the projected image vertically on the screen or wall.
		The vertical shift device 43 may be an electrically driven galvanometer mirror or a manually (mechanically) driven mirror that rotates on an axis to shift the position of the projected image vertically on the screen or wall.
		The vertical shift device 381 may be an electrically driven galvanometer mirror or a manually (mechanically) driven mirror that rotates on an axis to shift the position of the projected image vertically on the screen or wall.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1="20030174120".PGNR.&OS=DN/20030174120&RS=DN/20030174120 (7955 words)

	Thomson's Mirror Galvanometer (Site not responding. Last check: 2007-10-23)
		A sensitive galvanometer designed by William Thomson (later Lord Kelvin) in 1858 to detect the current through the Atlantic cable.
		A small mirror is suspended by a thread between two coils, and on the back of the mirror are glued several short and light magnets.
		The curved bar over the galvanometer case is a permanent magnet which can be rotated and raised or lowered to minimize the effect of the earth's magnetic field and to center the supension system.
	web.grinnell.edu /physics/PMuseum/MirrorGalv.html (95 words)

	William Thomson, 1st Baron Kelvin - Wikipedia, the free encyclopedia (Site not responding. Last check: 2007-10-23)
		Thomson invented the mirror galvanometer in response to the need for an instrument that could indicate with sensibility all the variations of the current in a long cable.
		The practical advantage of this extreme delicacy is that the signal waves of the current may follow each other so closely as almost entirely to coalesce, leaving only a very slight rise and fall of their crests, like ripples on the surface of a flowing stream, and yet the light spot will respond to each.
		The principle of the telegraph siphon recorder is exactly the inverse of the mirror galvanometer.
	www.secaucus.us /project/wikipedia/index.php/Lord_Kelvin (2877 words)

	Galvanometers (Site not responding. Last check: 2007-10-23)
		In the tangent galvanometer there is a circular coil having one or more turns of wire, at the center of which a magnetic needle is either balanced on a point or suspended by a fine fiber of silk or quartz.
		The galvanometer was purchased for Caltech's freshman physics lab in the fall of 1921.
		The galvanometer is graduated in degrees of the horizontal rotation.
	chem.ch.huji.ac.il /~eugeniik/instruments/test/galvanometers.htm (2541 words)

	Kelvin Exhibit -- Prolific Inventor
		The first commercially viable version of his mirror galvanometer was produced in 1858.
		Galvanometers were the predominant electrical measurement instruments of the 19th century.
		An example is the astatic mirror galvanometer that had quite a remarkable sensitivity, being capable of detecting currents in the order of 20 picoamperes (pA).
	www.physics.gla.ac.uk /Physics3/Kelvin_online/inventor.html (787 words)

	Multi-wavelength programmable laser processing mechanisms and apparatus utilizing vaporization detection - Patent ...
		The curvature of the concave cylindrical mirror 77, is typically tilted at a 45 degree angle in the X-Y plane, and is of a radius of curvature 78, that corrects the field curvature in the image plane 75.
		Galvanometer 50 permits bidirectional scanning, i.e., scanning of a beam on a workpiece from one end of a scan axis to the other end, and then retracing the scan axis from the second end back again to the first end.
		The curvature of the concave cylindrical mirror 104 is typically tilted at a 45 degree angle in the X-Z plane, and is of a radius of curvature 106 that also corrects the field curvature of focused beam 100" on the image plane 110 on detector 108.
	www.freepatentsonline.com /5751588.html (10490 words)

	Measurement instruments
		This is d’Arsonval’s galvanometer of the Siemens firm.
		The galvanometer is composed by a multiplier made of a long and thin wire.
		Through a slit it send a light beam onto the mirror that reflects it on graduated scale placed at a distance of 60 cm from the galvanometer and enhances the very small deviations.
	spazioinwind.libero.it /gabinetto_di_fisica/elmag/electricmeasuresu.htm (852 words)

	Help me ID this British galvanometer (Site not responding. Last check: 2007-10-23)
		Furthermore, it appears to be a mirror galvanometer.
		There is a coil suspended between the poles of the magnet and it is connected to the two terminals and has a resistance of 3,000 ohms.
		Mirror galvanometers were used on the receiving end of submarine telegraph cables.
	www.telegraph-office.com /pages/unknown_galvo_brit.html (303 words)

	oe magazine - Tutorial - Scanning the Scene (Site not responding. Last check: 2007-10-23)
		Galvanometers are used across a broad spectrum of industries including transportation, biotechnology, entertainment, medical diagnostics and therapeutics, and defense (see figure 1).
		Galvanometers project laser beams that are used in the construction of buildings and jets.
		Mirror size and shape is based on the diameter of the beam to be reflected, the incident angle, and the required scan angle.
	oemagazine.com /fromthemagazine/may04/tutorial.html (1485 words)

	Laser Focus World - CUSTOM OPTICS: New generation of applications raises performance bar for scanning mirrors
		In a galvanometer scanner, mirror inertia is often the fundamental limitation on the maximum frequency at which scanning can be performed, and on the top acceleration that can be reached.
		Minimum required mirror size is determined by projecting the beam cross section on to the mirror surface at all angles of use.
		Mirror aspect ratio (the substrate diameter or diagonal length, divided by its thickness) also affects the ability to achieve a given flatness specification or clear-aperture value.
	www.laserfocusworld.com /articles/article_display.html?id=257231 (1652 words)

	How Laser Shows Work - Scanning Systems - www.LaserFX.com
		The galvanometer (often abbreviated to galvo) is a current-sensitive device that operates in a similar manner to an analogue meter.
		The position of the shaft (and it's attached mirror) is derived from the photo detector in the position detection circuit, which sends that signal to a position correction circuit.
		The position correction circuit compares the actual position of the mirror, with the position the mirror should be in according to the signal from the input conditioning circuit.
	www.laserfx.com /Works/Works3S.html (1687 words)

	Cambridge Technology: Choose A Closed Loop Galvanometer Based Scanner
		A galvo system consists of three main components: the galvanometer, the mirror (or mirrors) and the servo driver board that controls the system.
		The ability to execute large-angle steps with low cross-scan mirror wobble and timing jitter, together with high galvo power-handling capacity, are critical as extreme levels of repeatability from scan to scan at high repetition rates are required.
		The closed-loop galvanometer offers the system designer a powerful combination of speed, accuracy and low cost, as well as a flexibility that is not possible with other scanner technologies.
	www.camtech.com /news/Choosing_A_Galvanometer.html (1860 words)

	D'Arsonval Galvanometer
		Since the electro-magnetic torque is proportional to the current in the coil and the restoring toque is proportional to the angle of twist of the suspension fiber, at equilibrium the current through the coil is linearly proportional to its angular deflection.
		Self-contained galvanometers, such as the one by Rubicon at the right, used to be standard equipment for voltage measurements with a potentiometer.
		A 6 volt light bulb is used as a optical source, and, after a parallel beam is formed with a stop and a lens, the beam reflects from the mirror on the galvanometer movement, and, after several reflections inside to lengthen the optical lever, falls on the frosted-glass scale.
	physics.kenyon.edu /EarlyApparatus/Electrical_Measurements/DArsonval_Galvanometer/DArsonval_Galvanometer.html (678 words)

	Olympus FluoView Resource Center: Introduction to Confocal Microscopy
		As the laser is reflected by a dichromatic mirror and scanned across the specimen in a defined focal plane, secondary fluorescence emitted from points on the specimen (in the same focal plane) pass back through the dichromatic mirror and are focused as a confocal point at the detector pinhole aperture.
		The speed of the scanning mirrors is very slow relative to the speed of light, so the secondary emission follows a light path along the optical axis that is identical to the original excitation beam.
		After leaving the scanning mirrors, the fluorescence emission passes directly through the dichromatic mirror and is focused at the detector pinhole aperture.
	www.olympusconfocal.com /theory/confocalintro.html (4303 words)

	Ancillary equipment
		The standard technique of drum recording is to illuminate the galvanometer mirror with light from a vertical line source, and to bring an image of the source into focus on the recording surface by means of a convex lens in front of the galvanometer mirror.
		A rocking prism or mirror between the light source and the galvanometer displaces the image to provide timing marks or a shutter is used to interrupt the light beam.
		Galvanometers should be connected so that North, East and Upward motion of the ground moves the trace towards the top of the page.
	www.seismo.com /msop/msop79/inst/inst6.html (4309 words)

	Poggendorff (Site not responding. Last check: 2007-10-23)
		In the same year (1826) as Nobili constructed his new galvanometer, Poggendorff invented a method of reading a galvanometer scale by means of a mirror - he designed a mirror galvanometer.
		The design of a mirror galvanometer comprises a coil of wire wound on a soft iron core suspended in the magnetic field of a permanent magnet - this coil is suspended generally by means of a strip of phosphor bronze wire and located centrally between the poles of the permanent magnet.
		A small mirror is attached to the coil so that a beam of light reflected by this mirror will sweep through an angle which is proportional to the current passing through the coil.
	chem.ch.huji.ac.il /~eugeniik/history/poggendorff.html (355 words)

	Thomson's Mirror Galvanometer
		A sensitive galvanometer designed by William Thomson (later Lord Kelvin) in 1858 to detect the current through the Atlantic cable.
		A small mirror is suspended by a thread between two coils, and on the back of the mirror are glued several short and light magnets.
		The curved bar over the galvanometer case is a permanent magnet which can be rotated and raised or lowered to minimize the effect of the earth's magnetic field and to center the supension system.
	www.grinnell.edu /physics/PMuseum/MirrorGalv.html (95 words)

	Untitled Document
		In the succeeding winter he invented his mirror galvanometer which was designed to detect even the faintest currents.
		It comprised a small mirror affixed to a tiny magnet; the mirror reflected the light from a lamp on to a scale that was graduated in degrees.
		The galvanometer rendered invaluable service throughout, its tiny spot of light being observed 'as anxiously as a physician watches a patient during a crisis'.
	www.assumption.edu /ahc/desktopatlan/PageDesign/CastThomson.html (1096 words)

	Galvanometer (Site not responding. Last check: 2007-10-23)
		Galvanometer - An instrument used to detect, measure, and determine the direction of small electric currents by means of mechanical effects produced by a current-carrying coil in a magnetic field.
		Galvanometer is an electromechanical instrument which is used for the detection of electric currents through a circuit.
		The deflection is measured by a pointer attached to the coil.
	www.closedloopgalvanometer.com (516 words)

	Sample HTML
		By placing a high resistance in series with the galvanometer, the current that flows through the combined resistance of the galvanometer and the additional resistance is proportional to the voltage applied.
		With the mirror stationary, light from the source strikes face A of the mirror, is reflected from this face to the distant mirror, then back to face C, and then to the eye of the observer.
		One pair of rays travels through the half-silvered mirror to mirror #1, back to the front surface of the half-silvered mirror from which it is reflected to observer.
	www.physics.brown.edu /physics/demopages/Demo/overheads/oh.html (3553 words)

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