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Topic: Beam divergence

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	Beam divergence
		Beam divergence: Of an electromagnetic beam, in any plane that intersects the beam axis, the increase in beam diameter with distance from the aperture from which the beam emerges.
		Note 1: Beam divergence is usually used to characterize electromagnetic beams in the optical 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 divergence 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_divergence.html (136 words)

	Beam divergence, and the directivity of an antenna
		Beam divergence, and the directivity of an antenna.
		For practical beams, where the radiation does not suddenly fall to zero at the cone edges, we may take the beamwidth between -3dB contours as (2 alpha), as alpha is the cone semi-angle.
		For a non-conical beam shape we can very roughly approximate the area of the beam footprint on the unit sphere as the product of the beam widths in E-plane and H-plane, or in azimuth and elevation.
	www.ee.surrey.ac.uk /Personal/D.Jefferies/antpoint.html (540 words)

	CASCADE LASER CORP.: Manual Laser Beam Expanders (Site not responding. Last check: 2007-10-21)
		Beam expanders are frequently used in combination with gas or solid state lasers in order to expand the exiting beam to the extent desired.
		To increase the transmission and to reduce scattered light, the elements of these beam expanders are coated with a reflection-reducing layer of the type V coordinated to their nominal wavelength; the laser diode beam expander (780 nm to 860 nm) has a broadband coating for 630 nm to 1070 nm.
		Divergence reduction: An immediate consequence of the inverted telescope principle used in the beam expander is the reduction in beam divergence inversely proportional to the expansion factor (when the telescope is inverted, its magnification factor gamma' becomes the reciprocal reduction factor).
	www.cascadelaser.com /beamexpand2.htm (1806 words)

	Beam Width Analysis (Site not responding. Last check: 2007-10-21)
		Beam divergence in a focused probe's beam is rarely considered.
		An " approximate" beam divergence for the phased array probe in the lateral direction is indicated using a " natural focus" of 2.7mm at 70mm along the beam axis.
		The divergence from the trendline information derived from the spherically focused indicates a 2.02° divergence after focused and this compares to 3.2° in the lateral plane for the phased array beam.
	www.ndt.net /article/v06n09/ginzel/ginzel.htm (1848 words)

	Introducing the Particle-Beam Weapon (Site not responding. Last check: 2007-10-21)
		As the particles of the beam collide with the atoms, protons, and electrons of the material composing the target, the energy of the particles in the beam is passed on to the atoms of the target much like a cue ball breaks apart a racked group of billiard balls.
		In describing a particle beam, it is conventional to speak of the energy of the beam (in electron-volts), the beam current (in amperes), and the power of the beam (in watts).
		If the beam were to diverge from a pencil point to only the diameter of a penny after twelve miles of travel, this would represent a divergence of one part in a million (one meter for each 1000 kilometers traveled).
	www.airpower.maxwell.af.mil /airchronicles/aureview/1984/jul-aug/roberds.html (5096 words)

	Transducer Beam Spread
		Beam spread is a measure of the whole angle from side to side of the main lobe of the sound beam in the far field.
		Beam divergence is a measure of the angle from one side of the sound beam to the central axis of the beam in the far field.
		Beam spread occurs because the vibrating particle of the material (through which the wave is traveling) do not always transfer all of their energy in the direction of wave propagation.
	www.ndt-ed.org /EducationResources/CommunityCollege/Ultrasonics/EquipmentTrans/beamspread.htm (766 words)

	LEOT Laser Tutorial - Course 1: Introduction to Lasers - Module 9: Spatial Characteristics of Lasers (Site not responding. Last check: 2007-10-21)
		Given the diameter (or spot size) of a laser beam and the diameter of a circular aperture upon which the beam is centered, calculate the fraction of the power transmitted through the aperture.
		Given the divergence angle of a laser beam and the focal length of a positive lens used to focus the beam, calculate the diameter of the focused spot.
		The laser beam diverges in the cavity as it strikes the output coupler, and would diverge even more outside the cavity if the second surface of the output coupler were flat.
	repairfaq.ece.drexel.edu /sam/CORD/leot/course01_mod09/mod01-09.html (3693 words)

	Teachers Supplements
		To determine divergence, measure the beam diameter at a distance of several meters from the laser.
		The brighter beams of the higher power lasers are better for large lecture hall demonstrations, for long-distance communications, and for research and lab work where detailed observation and measurements of diffraction patterns and interference fringes are desired.
		To compensate for the divergence of the light that is transmitted through the front mirror, the exterior surface of the mirror has a curve similar to that of a converging lens.
	www.metrologic.com /edu/global_info/spplmnts.asp (3980 words)

	Laser Focus World - Performance monitoring saves time and money
		Once the beam has been properly sampled, it is important that the software employed in the beam profiling can accurately and reproducibly display the subtleties necessary to characterize the beam.
		The advantage of divergence measurements is clear when one understands that the beam divergence is directly related to the focused spot size in the main beam (see "The arithmetic of beam analysis," p.
		, and the beam divergence, θ0, are proportional to the ratio of the m
	lfw.pennnet.com /Articles/Article_Display.cfm?Article_ID=145192 (1330 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
		If the beam divergence has been previously measured, the diameter of the spot at the laser output can be calculated.
	www.uslasercorp.com /envoy/m2.html (676 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)

	[No title]
		Along the path of the laser, the 1st beam steering mirror is used to aim the beam at the intersection of the 2nd steering mirror with the axis of the optical train.
		If the beam is not at all visible, you may have to calibrate occasionally in order see the low energy scatter of the beam indicating whether you are moving the mirror in the right direction or not.
		It indicates the intensity of the laser beam in a two-dimensional cross-section of the beam.
	www.spiricon.com /pdf/10928_a.doc (10583 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)

	Mini E-Beam Evaporator (electron beam evaporator)
		The power supply is constructed using simple and rugged technology which permits high electron beam powers up to 600W standard to be generated without the use of complex failure-prone electronics.
		This is an additional electrode which intercepts the edge of the emerging vapour beam.
		As the vapour leaves the crucible/rod it is partially ionised by the incoming electron beam.
	www.e-beam-evaporator.com (1095 words)

	Section 2.2: Properties of Laser Beams
		Laser beam is highly directional, which implies laser light is of very small divergence.
		This is a direct consequence of the fact that laser beam comes from the resonant cavity, and only waves propagating along the optical axis can be sustained in the cavity.
		The directionality is described by the light beam divergence angle.
	www.columbia.edu /cu/mechanical/mrl/ntm/level1/ch02/html/l1c02s02.html (595 words)

	[No title]
		For a thin fiber target the rms beam size at the laser is d theta where theta is the beam divergence angle and d the distance to the laser.
		At E835 the rms beam divergence was approximately 0.2 mr and the distance to the stripper foil 24 m for an rms size of 4.8 mm.
		We must reduce the beam divergence and/or greatly reduce the distance between the target and the laser.
	www.ps.uci.edu /~markm/antihydrogen/cooling.doc (839 words)

	Phase conjugation for realizing lasers with diffraction-limited beam quality and high average power
		Lasers with diffraction-limited beam quality at high average output power are essential to increase the efficiency for many applications, such as material processing, frequency conversion and plasma generation.
		The beam distortions are generated by thermally induced lensing and stress birefringence in the active material.
		For adjusting the polarization of the incident beam to the polarization of maximum amplification in the YAlO crystal we used a half-wave plate.
	moebius.physik.tu-berlin.de /lasergrp/pc/research.html (3296 words)

	Unisantis S.A. - Single Crystal Diffraction
		It is known that for the diffraction experiment to work best, various properties of the X-ray source such as the size and the intensity of the beam should be chosen to match the equivalent characteristics of the crystal.
		In protein crystallography, it is desirable that the dimensions of the X-ray beam impinging the sample are of the order as that of the sample size under examination.
		Furthermore, the intensity of the X-ray beam should be consistent across the sample and the intensity of the X-ray beam high enough such that the detection time of the sample is reasonable.
	www.unisantis.com /products-protein.html (290 words)

	World's First Blue-Violet Laser Diode with a New Low-Noise Beam Structure
		The stable beam structure produces a vastly improved stable laser beam, which yields the low-noise, low-operating current characteristics that are required in a light source for next-generation large-capacity optical disc systems like advanced DVDs require.
		The new stable beam structure made by ion implantation significantly improves laser beam stability and yields the low-noise, low-operating current characteristics that the optical disc system requires.
		The shorter wavelength of the blue-violet laser diode however allows the beam to be focused into a reduced spot, and therefore is the key to next-generation large-capacity optical disc systems.
	www.sanyo.co.jp /koho/hypertext4-eng/0203news-e/0313-e.html (766 words)

	Mirror Enhances Diode Laser Bar's Beam - April, 2004 (Site not responding. Last check: 2007-10-21)
		But a drawback is their poor beam quality: an asymmetric, elliptical beam whose divergence is typically several degrees in the "slow" axis and tens of degrees in the "fast" one.
		This approach cannot be used with a diode laser bar, however, because the high divergence and close spacing of the individual lasers would cause light from any one laser to reflect into its neighbors.
		The slow-axis beam divergence from a normal laser bar without the striped mirror was approximately 6.2°.
	www.photonics.com /spectra/tech/XQ/ASP/techid.1622/QX/read.htm (613 words)

	Light Ion Beam Fusion Technology at Sandia National Laboratories (Site not responding. Last check: 2007-10-21)
		Ion beams provide the ability for medium distance transport (4 m) of the ions to the target, and standoff of the driver from high-yield implosions.
		Further experimental and theoretical progress needs to be made in the important areas of plasma source formation, uniformity and purity, beam and source non-uniformity and the effects on divergence, and the interaction of plasmas and neutral layers with intense applied electric and magnetic fields.
		Beam generation and acceleration are done in one or two short, closely-coupled regions at high accelerating gradients (0.5 - 1 GV/m), well above the threshold for emission of electrons from electrode surfaces.
	www.sandia.gov /capabilities/pulsed-power/hedicf/ionsource (6988 words)

	Don K's Laser Page
		The minimum divergence rate of a visible red laser beam in milliradians is approximately equal to 1 divided by its initial width in millimeters.
		The divergence may not be apparent within a few meters of the lens, if the "waist" of the beam occurs at that point.
		The beam "waist" is a region that sometimes occurs if the lens is trying to make the beam converge at the same rate that the wave nature of light is trying to make the beam diverge.
	members.misty.com /don/laserdon.html (3373 words)

	Laser Diode Application Notes - Optima Precision Inc.
		The beam divergence is measured as the full angle and at the half-maximum intensity point, known as Full Width Half Maximum or FWHM.
		– The beam from the laser diode diverges as defined by the beam divergence specification.
		In coupling the laser diodes widely divergent beam into a lens or other device such as a fiber, the result is typically less than 100%.
	optima-prec.com /notes.htm (2577 words)

	F524-77(1992) Test Methods for Measuring Beam Divergence of Pulsed Lasers by the Apertured-Detector Technique ...
		Deviation of the beam from cylindrical symmetry may decrease the precision of the test methods.
		It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
		Aperture-detector technique; Double detector method; Single detector method; beam divergence of pulsed lasers,; Beam divergence; pulsed lasers, by apertured-detector technique,; Divergence; pulsed laser beams, by apertured-detector technique,; Lasers and laser applications; beam divergence (of pulsed lasers), by aperture-detector technique,; Threshold detectors; pulsed lasers, for measuring beam divergence; 31.260
	www.astm.org /DATABASE.CART/WITHDRAWN/F524.htm (325 words)

	External Cavity Controls Transverse Mode in VCSEL - August, 2003 (Site not responding. Last check: 2007-10-21)
		As the bias current of the device is increased, however, higher-order transverse modes often begin to oscillate, increasing beam divergence and decreasing beam quality.
		The resonator is a three-mirror configuration, with the back surface of the VCSEL and an external mirror serving as end mirrors and the diffraction grating acting as the turning mirror (Figure 1).
		The zero-order reflection from the grating is the laser output, and the first-order reflection is the intracavity beam.
	www.photonics.com /spectra/tech/XQ/ASP/techid.1581/QX/read.htm (541 words)

	Lasers (Science Tracer Bullet - Science Reference Services, Libraryof Congress)
		Optical feedback elements allow a beam of radiation to either pass once through the laser medium (i.e., as in a laser amplifier) or bounce back and forth repeatedly through the laser medium, amplifying the light (i.e., as in a laser oscillator).
		Laser light is emitted in a directional beam, and can be produced from the x-ray through to the ultraviolet, visible, and infrared radiation parts of the spectrum.
		Various types of lasers differ according to characteristics such as output wavelength or wavelengths, output power, duration of emission (i.e., pulsed or continuous), beam divergence and size, coherence, efficiency, and power requirements.
	www.loc.gov /rr/scitech/tracer-bullets/laserstb.html (1291 words)

	Photon Inc. - the Laser and Light Measurement Solutions Company (Site not responding. Last check: 2007-10-21)
		Photon Inc. is a leading supplier of laser and electro-optical instrument systems for fast and accurate measurement, testing and analysis of laser and light sources, optical components for telecommunications, and other applications.
		Photon manufactures a full spectrum of beam profiling instruments for pulsed and CW sources using scanning slits, pinholes, CCD arrays, goniometric, and knife-edge technologies.
		Analysis of these irradiance patterns provides ISO Standard Laser Beam Parameters, such as beam width, centroid and Gaussian fit, and optical fiber parameters in accordance with TIA/EIA standards, such as Mode Field Diameter, Effective Area, Numerical Aperture, and Refractive Index Profile, and more.
	www.photon-inc.com (146 words)

	NEWS ITEMS (Site not responding. Last check: 2007-10-21)
		Duarte, Multiple-return-pass beam divergence and the linewidth equation, Appl.
		Duarte and J. Piper, A double-prism beam expander for pulsed dye lasers, Opt.
		Duarte and J. Piper, Dispersion theory of multiple-prism beam expander for pulsed dye lasers, Opt.
	www.opticsjournal.com /news.htm (1069 words)

	Rami Arieli: "The Laser Adventure" (Site not responding. Last check: 2007-10-21)
		Every beam of light has certain divergence while it propagates.
		means that, as the beam propagate, the same amount of radiation spread over larger area.
		Lasers are the radiation sources with the least divergence available
	www.phys.ksu.edu /perg/vqm/laserweb/Ch-7/C7s2p1.htm (70 words)

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