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Topic: Electrostatic lens

	Night Vision Equipment
		Daylight Lens Cover - is usually made of soft plastic or rubber with a pinhole that allows a small amount of light to enter the objective lens of a night vision device.
		Focal length - is the distance from the optical center of a lens (or, the secondary principal point for a complex lens like a camera lens) to the focal point (sensor) when the lens is focused on an object at infinity.
		A 7mm focal length lens is always a 7mm focal length lens and a 300mm focal length lens is always a 300mm focal length lens.
	www.nightvisiongear.com /faq.asp (4052 words)

	Electrostatic lens - Wikipedia, the free encyclopedia
		An electrostatic lens is a lens that transports electrons emitted from a sample to an electron analyser.
		Systems of electrostatic lenses can be designed in the same way as optical lenses, so electrostatic lenses easily magnify or converge the electron trajectories.
		There are several types of electrostatic lenses: cylinder lenses, aperture lenses, and quadrupole lenses.
	en.wikipedia.org /wiki/Electrostatic_lens (312 words)

	Secondary Ion Mass Spectrometry Instrumentation Tutorial
		The electrostatic lenses and the apertures control the intensity and width of the primary ion beam.
		Electrostatic deflectors steer the primary beam in a raster pattern onto the sample.
		The secondary ions accelerate toward the ground plate of an electrostatic lens.
	pprco.tripod.com /SIMS/Instrumentation.htm (2219 words)

	I. THE MICROSCOPE (Continued)
		The lens is stronger in a plane perpendicular to the paper than in the plane of the paper, so that a point object O is imaged into two focal lines.
		Electrostatic fields are used in modern microscopes to stigmate the lens.
		Lens current stabilization takes place in a fashion similar to that for the high voltage except that it is usual to generate the lens current first and to stabilize it afterwards.
	www-ncmir.ucsd.edu /~gina/Sec-I.B/Sec-I.B.html (9841 words)

	ENEE 605:Design and Fabrication of Micro-Electro-Mechanical Systems (Site not responding. Last check: 2007-10-17)
		A traditional electrostatic lens consists of precisely aligned metal plates separated by a high quality insulator such as sapphire.
		Use electrostatic modeling and/or a ray tracing program (for example that found in Femlab) to design the dimensions and geometry of your lens.
		The ability to place the electrostatic lenses with precision (and with reasonable ease) is an essential component of this project.
	www.ee.umd.edu /class/enee605/grp/grp3.html (675 words)

	Kratos Instruments: The Magnetic Lens
		At long distances lens aberrations are large, and to obtain a reasonable degree of image resolution the input lens has to be apertured down, resulting in poor sensitivity.
		The magnetic snorkel lens, unlike conventional magnetic lenses, produces a field which is not confined within the mechanical lens structure.This enables a sample to be supported some distance away from the lens and provides a clear line of sight for excitation sources.
		The magnetic lens applied to electron spectrometry is a Kratos invention and is the outcome of years of ground breaking research and development in this field.
	www.kratos.com /Agen/MagLens.html (347 words)

	Glossary Terms: E (Site not responding. Last check: 2007-10-17)
		A lens employing a permanent magnet to produce a potential field capable of deflecting electron rays to form an image of an object.
		The apparent size of the limiting aperture of a lens or lens system (properly that of the diaphram), as seen from the object plane.
		The exit pupil of a lens system is an image of the entrance pupil (hence conjugate to it) and normally should be the image of the limiting diaphram.
	resolution.umn.edu /glossary/E.html (1148 words)

	PEM Home Page
		Data is collected and the focal properties of the lens are found using similar techniques as used in the experimental work.It is found that the experimental results of the hyperbolic lens support both the analytical study and the software simulation.
		It is also found that the experimental results of the hyperbolic lens closely match those of the conventionally designed lens, indicating that the hyperbolic model possesses properties that are general characteristics of all electrostatic lenses.
		The results also demonstrate that the hyperbolic lens is not free of spherical aberration, as has been previously posited in the relevant literature, but instead suffers from spherical aberration, as do conventional electrostatic lenses.
	web.pdx.edu /~wordr/PEEM/ToddAbstract.html (307 words)

	Electrostatic Components for Accelerators
		Lens settings are proportional to the energy of the ions divided by their charge, independent of mass.
		This NEC electrostatic quadrupole quadruplet lens (S.H. Sie and C.G. Ryan, Nuclear Instruments and Methods B15 (1986) 664) is designed to be part of materials analysis systems such as RBS and PIXE to provide elemental analysis of surface structures only 20 microns across.
		Although the lens is mass independent, it is presently used on instruments designed primarily for proton and helium beams.
	www.pelletron.com /escomp.htm (377 words)

	Lens Pen - FAQ (Site not responding. Last check: 2007-10-17)
		This feature is important, as electrostatic charge attracts dust and causes it to adhere to lenses.
		Extensive testing of LensPen on expensive lenses and lens coatings has proven that the cleaning compound is safe to all lenses and coatings.
		LensPen was tested by removing 500 fingerprints in a row from a lens with no discernible loss of cleaning quality.
	www.lenspen.com /404 (493 words)

	[No title] (Site not responding. Last check: 2007-10-17)
		That beam is collimated by electromagnetic condensor lenses, focussed by an objective lens, and scanned across the surface of the sample by electromagnetic deflection coils.
		The simplifications of the thin lens calculations come from the ability in many cases to consider the two principal planes to be coincident, or located at the same place.
		In an SEM, electro-magnetic lens are used almost exclusively for the condensor and objective lenses (some instruments refer to the objective lens as the final condensor lens, but I prefer using the term objective for this lens which is usually of a considerably different design than the condensors).
	www.sem.com /analytic/sem.htm (4648 words)

	[No title] (Site not responding. Last check: 2007-10-17)
		The lens, coupled to a cylindrical mirror analyser, considerably extends the energy range of the analyser to lower energies by acceleration of the electrons, and improves its angular resolution by angular magnification.
		The distribution of the potential in the lens was determined using series expansion, starting from a given function of potential at the lens axes.
		The power of the lens is demonstrated taking the spectrum of electrons emitted from He- on Ar collisions at 112 keV impact energy, in which the auto — ionization peaks originating from the (1s2p2p’) 4Pe shape resonance of He- are completely resolved.
	www.phy.bg.ac.yu /~centar3/acp19960.doc (6301 words)

	Story Page (Site not responding. Last check: 2007-10-17)
		The beam, which is diverging as it exits the gap, is refocused by an electrostatic lens to an appropriate size at the target position.
		The Duoplasmatron is a low pressure arc discharge source in which the gas to be ionized is electrostatically constricted by a funnel-shaped intermediate electrode placed between the filament and the anode.
		A strong axial magnetic field is developed between the intermediate electrode and the anode, which further constricts the discharge to a narrow plasma beam along the axis of the exit aperture.
	www.channel1.com /users/html/public/users/fchmara/page34.html (366 words)

	Exercise, Image Formation by a Converging Lens (Site not responding. Last check: 2007-10-17)
		is the distance from the object to the lens, and f is the focal distance of the lens.
		As the object is moved closer toward the lens, the image distance tends to zero from the negative side.
		Although the rays of light do not intersect, the mind perceives them to be coming from a point on the other side of the lens (this is shown by the dark green lines), which is infact the location of the virtual image.
	www.phys.hawaii.edu /~teb/optics/java/clens (386 words)

	ELECTROSTATIC LENS SYSTEMS, SECOND EDITION (Site not responding. Last check: 2007-10-17)
		If I were ever to have the pleasure of presenting a graduate course in electrostatic lens design and its application, this would certainly be a required text.
		Heddle devotes most of his effort in developing approaches to deal with axially symmetric lens systems, as these are the most commonly encountered in electrostatic optical systems.
		It is clear that Heddle favours the Bessel function expansion method, and he shows that this method has the advantage of speed, solving a test problem in 15 seconds while the 9-point finite difference method requires some 30 minutes to achieve the same accuracy in its solution.
	www.cap.ca /news/books/Electro-Heddle-Jensen.html (633 words)

	Nuclear Solid State Physics - Experimental Facility
		A 50 keV ion beam (for our purpose we typically use a 50 keV ion beam) is decelerated in the electrostatic lens which is mounted in a differentially pumped UHV section of the beamline.
		In front of the lens a faraday cup and beam profile monitor are installed to monitor the beam current and shape.
		First the ions are accelerated towards the entrance of the lens and subsequently slowed down in the lens so that they reach the sample with the desired energy.
	fys.kuleuven.be /iks/nvsf/Exp_Facility/lens.htm (470 words)

	I. THE MICROSCOPE (Site not responding. Last check: 2007-10-17)
		Consists of i) an objective lens which focuses the beam after it passes through the specimen and forms an intermediate image of the specimen and ii) the projector lens(es) which magnifies a portion of the intermediate image to form the final image.
		In a magnetic electron lens the focal length is determined by the field strength in the lens gap and by the speed of the electrons (determined by the accelerating voltage).
		Since the focal length of the lens is directly proportional to the accelerating voltage, a variation in the velocity of the electrons in the imaging beam affects image quality by eliminating perfect focus (chromatic aberration).
	em-outreach.ucsd.edu /web-course/Sec-I.A/Sec-I.A.html (7496 words)

	A Theorem on High-Order Geometric Spherical Aberrations for Hutter's Electrostatic Lens -- from Mathematica Information ...
		A Theorem on High-Order Geometric Spherical Aberrations for Hutter's Electrostatic Lens
		In this paper third-, fifth-, seventh-, and ninth-order geometric spherical aberrations for Hutter's electrostatic lens have been studied analytically and calculated numerically by means of Mathematica.
		This theoretical conclusion would be regarded as a complement of Scherzer's theorem on the third-order spherical aberration and may be helpful for estimating the effect of high-order spherical aberrations in electrostatic immersion lenses.
	library.wolfram.com /infocenter/Articles/5405 (149 words)

	EPG283: A new Form for the Third—Order Asymptotic Aberration Coefficients of Electrostatic Lenses (Site not responding. Last check: 2007-10-17)
		The third—order asymptotic aberration coefficients of round electrostatic lenses are reformulated in terms of the coordinates formed by the projections of the asymptotic incident and final rays onto the reference plane of the lens.
		In this formulation, all aberration coefficients are finite for all lenses, in contrast to the formulation in terms of coordinates projected onto the focal planes of the lenses, where all of the coefficients become infinite in the limit of very weak lenses and for certain strong lenses.
		Using these equations and previously calculated potentials and first—order trajectories, we have computed the six aberration coefficients for the accelerating and decelerating two—tube electrostatic lens for voltage ratios from 1.1 to 10000.
	physics.nist.gov /Divisions/Div841/Gp3/Pubs/abstract/epg283.html (178 words)

	An Analytical Study of First- and Third-Order Chromatic Aberrations for Hutter's Electrostatic Immersion Lenses -- from ...
		In this paper electron optical canonical aberration theory and the generalized integration transformation have been applied to Hutter's electrostatic immersion lens whose axial potential distribution has an exponential-arctangent form.
		As a result, analytical expressions of first- and third-order chromatic aberrations for such electrostatic immersion lenses have first been derived and numerical computations have been carried out by using a computer algebra language Mathematica.
		It is expected that this work may be useful for estimating first- and third-order chromatic aberrations in electrostatic immersion lenses.
	library.wolfram.com /infocenter/Articles/2220 (134 words)

	A 'movable' electrostatic lens
		A novel electrostatic lens system consisting of several short, closely-spaced elements is described.
		If such a lens has n independent voltages it can be used to maintain (n-1) properties of an image, or of more than one image, constant while other properties are varied, within the constraints imposed by the Helmholtz-Lagrange relationship.
		A movable three-cylinder lens is considered as an example and the necessary data are presented to enable three different pairs of image properties to be kept constant.
	stacks.iop.org /0022-3735/16/636 (251 words)

	PHYS 319 mid-term 1998
		(a) spherical aberration (b) chromatic aberration (c) diffraction and (d) all of the above vary with diameter of the aperture inserted at the back-focal plane of the objective lens.
		(f) Calculate the radius of the disk of confusion (referred to the specimen plane) introduced when the final image plane is lowered by 20 cm, assuming that the lens conditions remain the same and that the total magnification is 45 000.
		(d) The second condenser lens allows the diameter of illumination at the specimen to be continuously varied.
	laser.phys.ualberta.ca /~egerton/p319mt98.htm (540 words)

	ESTS0238: SIMION, Electrostatic Lens Analysis and Design
		In SIMION an electrostatic lens is defined as a two-dimensional electrostatic potential array containing both electrode and non-electrode points.
		The electrostatic fields are modeled as boundary value problem solutions of a Laplace elliptical partial differential equation.
		A finite difference technique called dynamically self-adjusting over-relaxation is applied to the two-dimensional potential array of points representing electrode and non-electrode regions to obtain a best estimate of the voltages for those points within the array that depict non-electrode regions.
	www.nea.fr /abs/html/ests0238.html (676 words)

	Prof. GONCHAROV, Alexey A. (Site not responding. Last check: 2007-10-17)
		Since 1985 he has focused on the investigation of high-current electrostatic plasma lenses for applications in high dose ion implantation and in heavy ion linear accelerators.
		In the recent years he concentrates on the researches and elaborations novel plasma generation devices based on plasma lens for advanced application in high-tech area.
		A.Goncharov, "Status of the electrostatic plasma lens", Rev. Sci.
	www.plasma.kiev.ua /people/goncharov.html (429 words)

	Electrostatic Lens Systems (Site not responding. Last check: 2007-10-17)
		This introduction to electrostatic optics gives data on simple lenses comprising two or three apertures or cylinders, as well as some more complex cylindrical lenses with more complex properties.
		Chapters cover the optics of a simple lens; the motion of charged particles in an electrostatic field; the determination of the axial potential; the optics of simple lens systems; and aberrations.
		Ray paths are traced in the paraxial approximation.
	www.booknews.co.uk /Books/1731.htm (139 words)

	Single pole-piece objective lens with electrostatic bipotential lens for SEM -- Yonezawa et al. 51 (3): 149 -- Journal ...
		Single pole-piece objective lens with electrostatic bipotential lens for SEM -- Yonezawa et al.
		Single pole-piece objective lens with electrostatic bipotential lens for SEM
		of a compound lens that consists of a single pole-piece objective
	jmicro.oxfordjournals.org /cgi/content/abstract/51/3/149 (220 words)

	Department of Physics, University of Alberta
		Assuming that the speed of the electron remains almost unchanged, calculate the energy transferred to the carbon nucleus.
		The field lines should bridge the gap between the polepieces and appear as curved lines which are symmetric on both sides of the optic axis.
		There it is deflected towards and crosses the optic axis before entering the objective lens, where it is focused back to the optic axis at the specimen plane.
	laser.phys.ualberta.ca /~egerton/p319f02.htm (1302 words)

	[No title] (Site not responding. Last check: 2007-10-17)
		In this way electrostatic lens systems are used to control beams of charged particle with various energy and directions in several fields, for example electron microscopy, cathode ray tubes, ion accelerators and electron impact studies.
		In an electrostatic lens system quantative information is required over a wide energy range and a zoom-type of optics is needed.
		We firstly calculated the optical properties of three and four element cylinder electrostatic lenses with the help of the SIMION and LENSYS programs and developed the method for the calculation of the focal properties of five and more element lenses with afocal mode.
	www2.bc.edu /~marulcu/Texts/MULTIEL.doc (376 words)

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