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Topic: Beam diameter

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	How To Measure A Beam Waist - Qwiki
		It is often necessary to measure the waist of a Gaussian beam in lab.
		This is used to find the beam measurements that are then used to calculate the beam parameters.
		If the beam is elliptical and the razor is drawn along either the major or minor axis, perfectly sensible results for the beam parameters along that axis will be given.
	qwiki.caltech.edu /wiki/How_To_Measure_A_Beam_Waist (169 words)

	Beam diameter
		Beam diameter: Of an electromagnetic beam, along any specified line that (a) intersects the beam axis and (b) lies in any specified plane normal to the beam axis, the distance between the two diametrically opposite points at which the irradiance[?] is a specified fraction, e.g., ½ or 1/ε, of the beam's peak irradiance.
		Note 1: Beam diameter is usually used to characterize electromagnetic beams in the optical regime, and occasionally in the microwave regime, i.e., cases in which the aperture from which the beam emerges is very large with respect to the wavelength.
		A beam may, for example, have an elliptical cross section, in which case the orientation of the beam diameter must be specified, e.g., with respect to the major or minor axis of the elliptical cross section.
	www.ebroadcast.com.au /lookup/encyclopedia/be/Beam_diameter.html (154 words)

	Apparatus for measuring the mode quality of a laser beam - Patent 5214485
		The advantage of obtaining the second beam diameter measurement at this location is that it is a precisely known distance from the previously measured transformed waist, namely the diameter D of the circle drawn by the aperture in a full rotation, which as noted above is being referred to as the diameter of the hub.
		The beam parameters displayed 210, 212 for the two principal planes are calculated for the input beam, with the Y-axis 212 highlighted indicating that is the primary principal plane (the lens is being servoed to focus that axis most critically on the rear aperture position).
		Pinhole diameters in the range of 25 to 50 microns for the larger diameter, and in the range of 5 to 10 microns for the smaller diameter, are believed to be adequate sizes to generate clean pinhole profiles for a wide variety of beams from commercial lasers in the present instrument.
	www.freepatentsonline.com /5214485.html (20440 words)

	Beam Weapons (Site not responding. Last check: 2007-10-12)
		The focusing array for lasers is similar to a telescope using the same wavelength as the beam; both varieties of particle beams are focused by magnetic lenses.
		Particle beam weapons thus have a shorter effective range than lasers, but the use of heavy ion beams at high currents means that they inflict much greater damage from a successful hit.
		For this reason, particle beam weapons are of greatest effectiveness when used against targets whose surface shielding is inferior to the power output of the attacking beam weapon, such as fighters and smaller capital ships.
	www.orionsarm.com /tech/beam_weapons.html (500 words)

	Teachers Supplements
		Beam diameter is the diameter of the laser beam cross section.
		Although the diameter of a helium-neon laser beam is less than a millimeter as is emerges from the aperture, it maybe expanded, collimated into a parallel-edge beam, or focused into a tiny point with various lenses and lens combinations.
		For example, the larger the original diameter of the beam, the less expansion is required to illuminate a given area, and the greater will be the intensity when it is focused to a fine point.
	www.metrologic.com /edu/global_info/spplmnts.asp (3980 words)

	Olympus FluoView Resource Center: Laser Systems for Confocal Microscopy
		The coherence and polarization characteristics of a laser beam are measured by the distribution of light in the beam cross-section, or profile, which changes with increasing distance from the exit mirror of the laser.
		When the Gaussian beam diameter is equal to the diameter of the lens aperture, the output beam intensity profile is a mixture of the Gaussian function and that of an Airy disk.
		When a laser beam is focused by a lens onto an optical fiber, the coupling efficiency and characteristics of the beam that emerges from the fiber depend heavily on the fiber geometry.
	www.olympusfluoview.com /theory/confocallaserintro.html (5325 words)

	Beam divergence - Wikipedia, the free encyclopedia
		The beam divergence of an electromagnetic beam is the increase in beam diameter with distance from the aperture from which the beam emerges in any plane that intersects the beam axis.
		Beam divergence is usually used to characterize electromagnetic beams in the optical regime, in other words cases in which the aperture from which the beam emerges is very large with respect to the wavelength.
		A beam may, for example, have an elliptical cross section, in which case the orientation of the beam divergence must be specified, for example with respect to the major or minor axis of the elliptical cross section.
	en.wikipedia.org /wiki/Beam_divergence (203 words)

	BeamPipeVacuumShortAns
		The proposed beam pipe is a small diameter pipe centered on the interaction region with larger pipes on either end, extending to the pumps on either side of the STAR hall.
		It is assumed that the transition from the small diameter pipe to the larger pipe is abrupt.
		Likewise, the outgassing surface in the large diameter section is treated as a point source at the midpoint of this larger section.
	www-rnc.lbl.gov /~wieman/BeamPipeVacuumShortAns.htm (454 words)

	Beam diameter - Wikipedia, the free encyclopedia
		Beam diameter is usually used to characterize electromagnetic beams in the optical regime, and occasionally in the microwave regime, i.e.
		cases in which the aperture from which the beam emerges is very large with respect to the wavelength.
		A beam may, for example, have an elliptical cross section, in which case the orientation of the beam diameter must be specified, e.g.
	en.wikipedia.org /wiki/Beam_diameter (135 words)

	Diffraction Limited Beams and Gaussian Optics
		Uniformly Illuminated Apertures: Generally, when discussing beam widths and beam shapes of microwave dishes and optical telescopes, it is usual to assume the simple case of uniform illumination, i.e., constant beam intensity across the aperture, with a sudden cut-off of the beam at the extremes of the aperture.
		Beam divergence for a beam with a Gaussian density profile.
		(4), and THETA3 = 0.0102", the corresponding FWHM diameter of the Gaussian beam at 10 L.Y. is:
	www.coseti.org /radobs14.htm (2178 words)

	US LASER CORP: Tech. Note Beam Quality and Determination of M²
		The technique is similar to focal plane divergence measurement technique with two major differences: (1) two diameters (instead of one) are taken at different locations along the beam; (2) the measurement of the actual beam waist and its position, not the diameter at the ideal waist position is used.
		is the theoretical "imbedded Gaussian" beam diameter, and 2
		The lens should be selected such that the focused beam diameter (times the square root of 2) on the CCD is as large as possible without overfilling.
	www.uslasercorp.com /envoy/m2.html (678 words)

	Compare the Properties of Wicked Laser Beams (Site not responding. Last check: 2007-10-12)
		Beam diameter and beam divergences are two of the most important technical specifications to consider when choosing a laser.
		Common senses tell us that if a laser beam diameter is small, it can go further and burn with more power than if it is big.
		However, at a distance of two meters, the beam diameter of the Nexus 95mW and the Evo 95mW are nearly identical; the burning capabilities are also nearly identical.
	www.wickedlasers.com /laser-tech/laser_beam_comparison.html (504 words)

	ALLEGRETTO WAVE Custom LASIK Excimer Laser System
		A small diameter laser beam or also known as spot size is very important for both accuracy and smoothness.
		If the size of the laser beam is larger the result is that the beam is too large to make fine adjustments throughout the cornea.
		The result is that with a small beam less than 1 mm with a gaussian profile allows for the proper and accurate treatment of the smallest curvatures of the cornea and also allowing for a smooth corneal surface.
	www.allegretto.ca /patient/beam.html (146 words)

	Beams
		The theory of beams was only perfected in the late 17th century with the rise of the science of elasticity, and was shown to be a subject of great complexity for which a full and accurate solution was very difficult.
		Two useful examples, especially for wooden beams, are the rectangular beam of height h and width b, and the circular beam of diameter d.
		The diameter of a circular beam is given at once; for the rectangular beam, we must decide on a ratio of the depth to the width, on the basis of other considerations.
	www.du.edu /~jcalvert/tech/beam.htm (6893 words)

	II-VI INFRARED: BEAM EXPANDERS (Site not responding. Last check: 2007-10-12)
		A beam expander is any optical system consisting of two or more elements which changes the size and angular divergence characteristics of a beam passing through it.
		Beam expanders have numerous uses: by expanding a beam prior to focusing, smaller focal spot sizes can be achieved.
		Beam expanders can also be used to reduce beam diameter which may be useful when using acousto- or electro-optic modulators.
	www.iiviinfrared.com /beamexp.html (88 words)

	Laboratory 2
		The variation of the beam diameter in the vicinity of the beam waist is given by
		First, the beam is diverged with a short focal length lens and then the diverging beam is re-collimated with a larger beam waist and smaller divergence.
		Use lens paper in the beam path to observe the incident as well as the reflected beam and adjust the mirror so that the reflected beam overlaps the incident beam.
	electron9.phys.utk.edu /optics421/Laboratories/Lab2.htm (827 words)

	Edmund Optics
		The beam diameter is first increased in size by this power and then the beam divergence is reduced by the same power.
		This equation is an approximation for the collimated output beam size at a given distance.
		The beam expander power (MP) is equal to the ratio of the effective focal length (EFL) of the objective lens to the effective focal length of the entrance optic.
	www.edmundoptics.com /TechSupport/DisplayArticle.cfm?articleid=270 (423 words)

	Melles Griot Optics Guide - Beam Waist and Divergence (Site not responding. Last check: 2007-10-12)
		The Gaussian shape is truncated at some diameter either by the internal dimensions of the laser or by some limiting aperture in the optical train.
		The spreading of a laser beam is in precise accord with the predictions of pure diffraction theory; aberration is totally insignificant in the present context.
		At the beam waist (z = 0), the wavefront is planer (R(0) = ∞).
	www.mellesgriot.com /products/optics/gb_2_1.htm (750 words)

	Frequently Asked Questions about CO2 lasers
		The smallest theoretical diameter is, roughly, wavelength of the beam.
		inversely proportional to the diameter of the beam.
		laser beam - due to diffraction and beam divergence which in turn are related to dimensions being finite - will focus to a spot size that is directly proportional to the focal length of the lens and inversely proportional to the diameter of the laser beam at the point it meets the lens.
	www.parallax-tech.com /faq.htm (3026 words)

	oe magazine - test talk (Site not responding. Last check: 2007-10-12)
		of the beam waist by moving the profiling tool along the optical rail from the beam waist toward the laser to the point at which the measured beam diameter is the Rayleigh diameter ˆ2 D
		to the other side of the beam waist by moving the profiling tool from the beam waist away from the laser to the point at which the beam diameter is again the Rayleigh diameter.
		For accurate results, the test lens diameter should be at least twice the input beam diameter to prevent clipping of the beam.
	oemagazine.com /fromTheMagazine/aug05/testtalk.html (628 words)

	Tech. Note - Measuring Laser Beam Divergence
		Since all laser beams diverge, the actual focus is located farther from the lens than the ideal focal length (see Figures 1 and 2 for an illustration).
		Once the beam diameter at the ideal focus is known, the beam divergence may be calculated using a simple formula.
		With the beam profiler, measure the beam diameter at this point in both the horizontal and vertical directions.
	www.uslasercorp.com /envoy/diverge.html (627 words)

	II-VI INFRARED: TUTORIAL: CHOOSING THE RIGHT FOCUSING LENS (Site not responding. Last check: 2007-10-12)
		To determine the input beam diameter which will provide minimum spot size we simply take the equation for spot size, differentiate it with respect to beam diameter, and then set it equal to zero to find the minimum value.
		The beam can be expanded or contracted by use of an IBEC type beam expander/condenser, or by constructing a beam expander/condenser using individual lenses.
		If it is not possible, or not desirable, to alter the beam diameter in the system, then one may wish to know what focal length to use to produce a minimum spot size.
	www.iiviinfrared.com /ttr_chooseflens.html (561 words)

	Microscan Main Page
		The Microscanning Beam Profiler can be mounted to stay directly in the beam path during operation of the laser.
		For laser beams with essentially non-Gaussian profile, Microline will output the beam diameter defined as the size of localization of 86.5% of the total laser beam power.
		The Model 600 beam profiler may also be used as a wide-scan optical multimeter to complete your laser beam characterization system.
	www.beamco.com /microscan.htm (150 words)

	Newport Corporation \| Tutorials/Training (Site not responding. Last check: 2007-10-12)
		When a beam passes through a lens, mirror, or dielectric interface, the diameter is unchanged but the wavefront curvature is changed, resulting in new values of waist position and waist diameter (or Rayleigh range) on the output side of the interface.
		At large distances from a beam waist, the beam appears to diverge as a spherical wave from a point source located at the center of the waist.
		In fact, the position of the beam waist changes contrary to what we would expect in geometric optics: the waist moves toward the lens as the focal length of the lens is increased.
	www.newport.com /servicesupport/Tutorials/default.aspx?id=112 (1650 words)

	Laser Beam Collimating is an Art Form (Site not responding. Last check: 2007-10-12)
		Beam diameter and beam divergence are the two most important technical specifications involved in choosing a laser.
		Beam diameter simply refers to the diameter of a laser beam, usually measured in millimeters.
		The actual physical diameter for a beam diameter of -4.5mm is 4.5mm (the absolute value of -4.5mm).
	www.wickedlasers.com /index.php?p=page&page_id=laser_beam (702 words)

	Section 2.7: TEM Mode, Beam Diameter,
		When a beam of finite diameter D is focussed by a lens onto a plane, the individual parts of the beam striking the lens can be imagined to be point radiators of new wave front.
		For a rectangular beam with a plane wave front, the diffraction limited beam diameter, which is the smallest focal diameter, is given by:
		is the wavelength, f is the lens focal length, D is the unfocussed beam diameter.
	www.columbia.edu /cu/mechanical/mrl/ntm/level2/ch02/html/l2c02s07.html (737 words)

	TEL-Atomic - Determination of e/m (Site not responding. Last check: 2007-10-12)
		Using the gas filled tube, the deflection of electron beams in a uniform magnetic field (with the use of Helmholtz coils) provides a means of quantitatively determining the charge-to-mass ratio of the electron, e/m.
		The tube’s n electron beam system consists of an indirectly heated oxide cathode, a Wehnelt cylinder and a perforated anode, in neon residual gas at a precisely set pressure.
		Integrated measurement marks for parallax-free determination of the diameter of the fine beam is also part of the electron beam assembly.
	www.telatomic.com /eoverm.html (214 words)

	BTeV Vacuum System & Beam Pipe Mechanical Design (Site not responding. Last check: 2007-10-12)
		An assembly drawing of the beam pipe assembly from the end of the pixel detector to the ion pump (z=8m) is posted on the
		The transition of the forward beam pipe to the RICH beam pipe is a low-mass flange.
		One of the candidates for the material of the forward beam pipe is a sandwich composite made of aluminum foil and Rohacell (a polymethacrylimide) foam core.
	home.fnal.gov /~mlwong (2527 words)

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