Charged particle dynamics inside electrostatic quadrupole. One difference concerns their respective aberrations. Accepted 8 10 2012 abstract the paper handles a new method that is utilized in determining the best bore diameter of two. V ery often ion optics with electrostatic lenses is called electron optics. Parameters of a single lens composed of two coaxial cylinders have been numerically calculated for the case of energy spread in a chargedparticle beam. Chapter 2 particle motion in electric and magnetic fields. Alabdullah department of physics college of science university of mosul received 5 2012. Pdf the effect of bore diameters in two electrodes. The term optics is used because magnetic and electrostatic lenses act upon a charged particle beam similarly to optical lenses upon a light beam electron optics calculations are crucial for the design of electron microscopes and particle accelerators. Systems of electrostatic lenses can be designed in the same way as optical lenses, so electrostatic lenses easily magnify or. The results obtained for the objective magnetic lens and the electrostatic lens for the preferable design were compared with the results of the recent published papers. Theoretical study of short electrostatic lens for the columbia ion microprobe alexander d.
Electrode geometries for the three einzel lens models. In terms of lens design, this means that the aperture, or f number, of an electrostatic lens is usually limited to keep these aberrations to a tolerable level. This book enables readers to design lens systems having useful characteristics. Here, the use of commercially available optical design programs is described as a tool to aid in solving charged particle optics problems. Very often ion optics with electrostatic lenses is called electron optics. It is shown that the focusspot size calculated from the classical formulas taking into account the coefficients found is in good agreement with the. This principle states that the interaction between any two charges is completely unaffected by the presence of other. Electron optics is a mathematical framework for the calculation of electron trajectories along electromagnetic fields. Related content the design of threeelement electrostatic electron lenses d w o heddlethe magnification behaviour of a fiveelement electrostatic lens d w o heddle and n papadovassilakis. If the cylinder is very long or is terminated without distorting the field within, the trajectories of charged particles inside it. A solenoid lens is the magnetic equivalent of the electrostatic einzel lens. We deal with eqds consisting of electrode pairs with rotational symmetry design. Simple analytical method to design electrostatic einzel lens.
An einzel lens is an electrostatic device used for focusing charged particle beams. Spectacle lens design the goal of the spectacle lens designer is to give the patient clear vision at all distances through any portion of the spectacle lens. A method of controlling deflection of a charged particle beam in an electrostatic lens includes establishing a symmetrical electrostatic lens configuration comprising a plurality of electrodes disposed at unadjusted positions that are symmetric with respect to the central ray trajectory with applied unadjusted voltages that create fields symmetric with respect to the central ray trajectory. Even though all electrostatic lenses are thick you can go quite far with simple, thin lens, ideas though ultimately you will need accurate data. Simion is an electrostatic lens analysis and design program. In this research, design electrostatic einzel lens threeelectrode accelerating and decelerating l2mm, 20mm operated under different.
He has a very limited number of degrees of freedom. An improvement in the optical properties obtained by the proposed design was noticed to be improved compared to the published results. The modification of an existing design or the generation of a completely new one is performed interactively with a graphics screen and mouse. The energetic electrons produce an enhanced copy of the light image when they strike a phosphor screen. The paper handles a new method that is utilized in determining the best bore diameter of two electrodes of the electrostatic lens design. This particular model consists of three axially aligned cylinders.
Electrostatic lenses are of great importance in the design of low energy electrostatic accelerators like cockcroftwalton and. The text covers the basic theory of the motion of charged particles in electrostatic fields and describes several methods for the calculation of the potential and field distribution for various electrode geometries. Mems lens scanners for freespace optical interconnects by jeffrey brian chou. A method of design for electrostatic lenses with given source parameters, first. Cn103688334a method and apparatus for controlling an.
The spherical and chromatic aberration coefficients of this lens have been determined. The potential and field are evaluated by the simple analytical method for a particular cylindrical einzel lens and optical properties are also evaluated approximately by the simple optical method following the section model. As an example, we can consider the treatment of cylindrical electrostatic lenses. Electrostatic force and electric charge electrostatic force charges at rest. Electrostatic lens systems, 2nd edition 2nd edition d. Different potential functions are used to describe a a threeaperture lens, b a threetube lens and c a twoaperture, centertube lens. Pdf theoretical design of electrostatic lens accelerating and. Mems lens scanners for freespace optical interconnects. An electrostatic lens system for the deceleration of high. This is different from a regular motor, which is based on magnetic. Brenner, gary johnson, and gerhard randerspehrson raraf, columbia university, 6 south broadway, irvington, new york 10533. In cgs electrostatic system, the unit of charge is called as statecoulumb or esu of charge.
The electrostatic field to calculate the force exerted by some electric charges, q1, q2, q3. In the optimization process of a transfer optics consisting of five einzel lenses, a comparison with the results obtained by means of the charge density method has proven, that this rather simple potential model is sufficiently accurate to allow a reliable preselection of promising lens designs. However, the bore diameter is considered the most important geometrical parameter in any electron optical. Even though all electrostatic lenses are thick you can go quite far with simple, thin lens, ideas though ultimately you will need accurate data to produce or analyse the final design. The general properties of electrostatic lenses and the electrostatic immersion lens are also considered. Tutorial model of an einzel lens comsol multiphysics. Design of the objective magnetic and electrostatic lenses. The concern is the control of the transverse motion of particles by shaped electric and magnetic fields.
In order to obtain an optimum design, it is necessary to reduce the aberration of the focusing lenses. Electron beams, lenses, and optics, volume i deals with the physics of electron beams, lenses, and optics and covers topics ranging from the paraxial ray in symmetrical electric fields to the analytical determination of electrostatic fields. The potential array is refined using overrelaxation methods allowing voltage contours and ion trajectories to be computed and plotted. One embodiment relates to an electronicallyvariable electrostatic immersion lens in an electron beam apparatus. The lens design was optimized using the simulation data obtained with a performance characteristics of the electrostatic lens system.
Electric and magnetic field lenses the subject of charged particle optics is introduced in this chapter. The traditional approach to lens design has been either to confine the problem to situations where the approximate solutions of the paraxial ray equations could be used, or to find a good handbook where numerical. Electrostatic lenses are of great importance in the design of low energy electrostatic accelerators like cockcroftwalton and vandegraaff accelerators. This work focuses on the design and implementation of an electrostatic lens system to produce highintensity, lowenergy ion beams, by means of numerical simulation of the beam trajectories simion 7.
Electrostatic lenses are used for the extraction and acceleration of electron and ion beams. Electrostatic lenses are of great importance in the design of low energy electrostatic. Then for an arbitrary set of the electrode potential. An electrostatic lens is a device that assists in the transport of charged particles. Electrostatic lens article about electrostatic lens by. Theoretical study of short electrostatic lens for the. The electrostatic immersion lens includes a top electrode configured with a first voltage applied thereto, an upper bottom electrode configured with a second voltage applied thereto, and a lower bottom electrode configured with a third voltage applied thereto. A possible electrostatic lens consists of a cylindrical surface along which the potential varies as the square of the distance from some original plane. The book covers the basic theory of the motion of charged particles in electrostatic fields and describes several methods for the calculation of the potential and field distribution for various electrode geometries.
In this system electrostatic constant c1 for vacuum or air, one stat coulomb is defined that amount of charge which when placed at a distance of 1 cm in air from an equal. Electrostatic lenses are used for the extraction, preparation and rst acceleration of electron and ion beams. A computeraided design of focused ion beam fib system consisting of three electrostatic lenses approximated by the spline lens model, has been investigated in the present work. In general, electrostatic lenses have much larger aberrations than their optical counterparts. However, the four element lens systems can be operated with a constant magnification while keeping the image position also constant. The outer cylinders are grounded, while the cylinder in the middle is held at a fixed. Optimum design of electrostatic lenses 954 solving laplaces equation with the given boundary condi tions. Research of the national bureau of standards 76a 2735. Three element cylindrical electrostatic lens systems for. The electrode bore shape is the most important geometrical parameter in any electron optical.
The objective lens includes a magnetic pole piece and an electrostatic deflector configured within the pole piece. Practical conditions specify lens materials, safety considerations fix lens thickness, fashion dictates lens. Second edition enables readers to design lens systems for focusing beams of charged particles that have useful characteristics. Kuoyung hung, chaochih fan, fangang tseng, and yiko chen, design and fabrication of a copolymer aspheric biconvex lens utilizing thermal energy and electrostatic force in a dynamic fluidic, opt. This paper describes the influence of the front electrode bore angle on the electron optical performance of the twoelectrode electrostatic immersion lens. Prediction of twoelement cylindrical electrostatic lens parameters.
This systems was predesigned for an ion beam modification and trajectory controlling. Electrostatic lens systems with more than four elements are generally used in. For instance, it can guide electrons emitted from a sample to an electron analyzer, analogous to the way an optical lens assists in the transport of light in an optical instrument. Exploring focal and aberration properties of electrostatic lenses. Request pdf design of an electrostatic lens using the charge density method a computational investigation has been. The focusing characteristics of electron beam in twoelement cylindrical lens systems are investigated with two different nonlinear autoregressive. These fields bend charged particle orbits in a manner analogous to the bending of light rays by shaped glass lenses. This type of motor is based on coulomb forces, and its energy output is related to the change in electrostatic energy that occurs when charges are moved between the terminals of a highvoltage hv supply. Improved digital methods for the precise calculation of electric fields and trajectories. Electronicallyvariable immersion electrostatic lens. In simion an electrostatic lens is defined as a twodimensional electrostatic potential array containing both electrode and nonelectrode points. The design of the lens incorporates space for the scanning coils, the stigmator, and the beamlimiting aperture n all modern fe sems employ a semiimmersion lens design u sample sits in an electromagnetic or electrostatic field generated by the lens u significantly lowers spherical aberrations allowing better resolution. Electrostatic lens article about electrostatic lens by the free dictionary.
Accurate calculations of properties of the twotube electrostatic lens. Electric and magnetic field lenses 108 6 electric and magnetic field lenses the subject of charged particle optics is introduced in this chapter. Design of the objective magnetic and electrostatic lenses for low. The book covers the basic theory of the motion of charged particles in electrostatic fields and describes several methods for the calculation of. An electrostatic field with axial or plane symmetry which acts upon beams of charged particles of uniform velocity as glass lenses act on light beams. The effect of bore diameters in two electrodes electrostatic immersion lens design muna a. Electrostatic force can be attractive electrostatic force can be repulsive electrostatic force acts through empty space electrostatic force much stronger than gravity electrostatic forces are inverse square law forces proportional to 1r 2. Optics elements for modeling electrostatic lenses and.