Abstract: An electron beam scanning system producing an electron beam in a relatively short chamber includes an ion controlling electrode assembly located between the electron gun and system beam optics. The assembly includes a somewhat cone-shaped rotating field ion controlling electrode ("RICE") unit disposed between first and second ion controlling electrode units ("ICE"s). The RICE and ICEs each comprise element pairs symmetrically disposed on opposite sides of the chamber Z-axis, preferably forming regular polygons in cross-section. Preferably corresponding elements in each ICE are electrically coupled to each other and to an opposite element in the RICE. Preferably equal and opposite bias potentials, with respect to an average potential, are coupled to the RICE and ICE elements comprising an element pair. Because it is somewhat cone-shaped, the RICE and electron beam create a transverse electric field with no axial component.

Abstract: A dynamic correction arrangement for an electron beam projection/deflection system provides high order correction values for deflection in accordance with a correction equation. Particularly as applied to high accuracy telecentric deflection, the coefficients of terms of the correction equation may be determined by calibration for a small number of test points. Correction values may be stored in a look-up table or computed in real time by using a math co-processor in a processing pipeline. The correction provided corrects landing angle errors through the third order in telecentric projection/deflection systems such as systems utilizing variable axis immersion lenses.

Abstract: An electron beam exposure system having an electromagnetic lens for forming an electron beam into an arbitrary image and for condensing and projecting the image on a sample, and a plurality of saddle type electromagnetic deflectors for deflecting and scanning the electron beam on the sample, wherein at least one of the plurality of saddle type electromagnetic deflectors has a half angle of arc of more than 60 degrees and positions in a vicinity of a smooth connecting line which links four points plotted on a graph having coordinates of the half angle of arc of 60 degrees to no less than a radius of curvature of 30 millimeters, approximately 61.5 degrees to 14 millimeters, approximately 64 degrees to 9 millimeters, and approximately 66 degrees to 7 millimeters. Thus, the electron beam exposure system having the saddle type electromagnetic deflector and which is small and has low aberration is realized.

Abstract: An electron beam projection apparatus providing a magnetic refocusing lens for adjusting a focal position of an electron beam on an object. An axis of an auxiliary magnetic field produced by the magnetic refocusing lens is required equivalently to agree to that of a convergent magnetic field produced by a magnetic object lens. An inclination adjustment apparatus of the magnetic refocusing lens provides a rolling mechanism being independently rotatable on two axes being perpendicular to each other and also perpendicular to a direction of an axis of a convergent magnetic field. With this inclination adjustment apparatus, adjustment operation is improved.

Abstract: In an electron optical system a monopole shaped magnetic field is introduced enabling an aberration free imaging writing or detection in the system. Apparatus based on this field distribution result in improved secondary electron detection such as for chip inspection, in improved resolution in Auger electron detection for analysis, in a higher exactness in chip production in an electron beam pattern generator and in an electron beam image projector in which now also size reduction can aberration free be introduced.

Abstract: An electron beam exposure system comprises a beam source for producing and directing an electron beam along an optical axis, an evacuated column for accommodating the beam source and extending along the optical axis, an electron lens for focusing the electron beam on a substrate; and an electromagnetic deflector supplied with a control signal for deflecting the electron beam in response to the control signal.

Abstract: High magnification and large depth of field with a temporal resolution of less than 100 microseconds are possible using the present invention which combines a linear electron beam produced by a tungsten filament from an SX-40A Scanning Electron Microscope (SEM), a magnetic deflection coil with lower inductance resulting from reducing the number of turns of the saddle-coil wires, while increasing the diameter of the wires, a fast scintillator, photomultiplier tube, photomultiplier tube base, and signal amplifiers and a high speed data acquisition system which allows for a scan rate of 381 frames per second and 256.times.128 pixel density in the SEM image at a data acquisition rate of 25 MHz. The data acquisition and scan position are fully coordinated. A digitizer and a digital waveform generator which generates the sweep signals to the scan coils run off the same clock to acquire the signal in real-time.

Abstract: A novel parallel-filament type electron gun for electron beam irradiation accelerators or generators and the like having a plurality of longitudinally extending parallel transversely spaced substantially co-planar similar filaments for generating electrons and disposed between a lower co-extensive extractor grid and an upper co-extensive electrostatic lens surface for shaping the electron beam profile, and with constructional features that enable variable width and extremely wide guns to be achieved and with improved beam uniformity.

Abstract: This invention provides for an integrated electron optical/differential pumping/imaging signal detection system for an environmental scanning electron microscope (ESEM). The ESEM includes a substantially cylindrical objective lens magnetic housing containing an axially disposed vacuum liner tube and containing means for magnetically focusing a beam of electrons passing through said liner tube. An annular ring comprised of magnetic materials abuts said magnetic housing at the lower end thereof and contains at least two pumping ports therein located axially with respect to one another. At least two annular nonmagnetic diaphragms and a final magnetic annular diaphragm are attached to the annular ring at different axial locations and extending inwardly therefrom. The diaphragms define at least two interior passages which each communicate with one of the pumping ports formed in the annular ring.

Abstract: An electron beam device having a single pole electromagnetic objective lens whose pole top face is positioned in front of a sample as viewed from the side of an electron beam source. A secondary electron detector is provided in the vicinity of the pole top face of an inner cylinder of the objective lens. The objective lens has a circular cylindrical or conical shape at the top of the objective lens and the vertical angle of the circular cylindrical or conical shape is 45.degree.-90.degree.. The working distance between the top of the objective lens and sample is less than 6 mm. It is possible to survey the sample with a resolving power corresponding to a dimension about one-half that of the prior art under low accelerating voltage conditions.

Abstract: In an electron microscope correction of spherical and chromatic aberration can be achieved in a number of freely adjustable directions by using a multipole correction element whereby a magnetic or electrostatic octupole field, rotatable about the optical axis, or a combined rotatable magnetic and electrostatic quadrupole field is generated. A corrected overall image can be obtained by combination of images successively corrected in different directions. In the case of holographic images, correction in the direction perpendicular to the line direction in the hologram enhances the accuracy of phase determination. A correction element of this kind, having comparatively small dimensions of from 1 to 2 cm, can be simply mounted, notably in a transmission electron microscope, in a space provided for the stigmator.

Abstract: The apparatus of the present invention selects from particles emitted by a radioactive source those particles having momentum within a desired range and focuses the selected particles in a beam having at least one narrow cross-dimension, and at the same time attenuates potentially disruptive gamma rays and low energy particles. Two major components of the present invention are an achromatic bending and focusing system, which includes sector magnets and quadrupole, and a quadrupole doublet final focus system. Permanent magnets utilized in the apparatus are constructed of a ceramic (ferrite) material which is inexpensive and easily machined.

Abstract: An electron beam scanning system employing a relatively short housing chamber wherein an electron beam is produced includes an ion controlling electrode assembly. Located in the housing between the electron gun and system beam optics, the assembly includes a generally cone-shaped rotating field ion controlling electrode (or "RICE") unit comprising cylindrically symmetrical element pairs disposed on opposite sides of the housing Z-axis. Preferably equal and opposite potential sources coupled to elements comprising an element pair create a transverse electric field therebetween. The vector sum of the fields produced by all element pairs is the transverse field created by the RICE unit. The potentials are varied, rotating the overall RICE field to controllably remove most but not all positive ions. The remaining ions improve the electron beam space-charge density, resulting in a sharply focused scanning electron beam.

Abstract: A condenser means for focusing an electron beam onto a specimen and a scanning means for scanning the beam in two dimensions on the specimen placed inside a specimen chamber are disposed inside an electron beam column. The top portion of the specimem chamber is connected with the column by an annular member of a high magnetic permeability which surrounds the column. Magnetic flux passed through the top wall of the chamber is made to penetrate the annular member of a high magnetic permeability. The flux is then caused to enter the portion of the upper wall remote from the column, after which the flux leaks out. Thus, leakage of the magnetic flux into the specimem chamber is prevented.

Abstract: The invention is directed to an electron energy filter which is assembled from three or four plates placed together in a sandwich-like configuration. The pole pieces are seated on the inner sides of the outer plates and attached thereto. The pole pieces can therefore be produced in pairs so that their outer surfaces match precisely. This assembly is economical and provides a precise manufacture.

Abstract: A charged particle beam lithography system includes a beam source of a charged particle beam, a beam shaping aperture for providing a predetermined cross section to the charged particle beam, a first focusing system for focusing the charged particle beam on a first crossover point located on the optical axis, a second focusing system provided between the first crossover point and an object for focusing the charged particle beam on a second crossover point located on the optical axis, a beam deflection system for deflecting the electron beam such that the beam is displaced on the surface of the object, a stage for supporting the object, a mask provided in a vicinity of said first focusing system, and an addressing system for selectively deflecting the charged particle beam such that the charged particle beam is passed through a selected aperture on the mask.

Abstract: The charged-particle beam apparatus according to this invention is of the type in which a specimen is inserted between the upper and lower magnetic poles of an objective lens, and is constructed such that stages, which are used to move a specimen in a desired direction, are mounted one on top another from the bottom wall of the objective lens, thus preventing the specimen from being affected by external vibration. Devices, which do not generate a magnetic field, are used to drive the stages. This enables the drive devices to be directly connected to the stages, so that the stages are moved accurately.

Abstract: Particle beam apparatus for improving the spatial resolution of a conventional scanning electron microscope given low electron energies and adequately great working distances, an electrostatic immersion lens is arranged in the region of an intermediate image generated by a condenser unit. The immersion lens is composed of a beam-guiding tube that is at an anode potential and of a further tube electrode that is arranged and insulated in the column of the scanning electron microscope and is charged with a high positive potential. Since the tube electrode extends into the region of the pole piece gap of the objective lens, an electrical field that decelerates the electrons to the desired ultimate energy is built up at this location. Due to the retarding field overlaid on the focusing magnetic field of the objective lens, the lens has extremely low chromatic aberration and spherical aberration constants.

Abstract: A thermally stable magnetic deflection assembly for use in an electron or particle beam machine with several separately potted magnetic coils spaced apart and arranged in a particular vertical position on a central pipe. Non metallic, low coefficient of thermal expansion, highly thermally conductive materials are used throughout and means are provided for maintaining the entire assembly at a desired temperature. Also disclosed is a method of making a thermally stable magnetic deflection assembly.

Abstract: Method and an apparatus for automatically moving the focal plane of the electron beam produced by a scanning electron microscope to the position of specimen surface. An auxiliary coreless coil of a low inductance is disposed close to the objective lens. The exciting current fed to the coil is varied to move the focal plane of the electron beam toward the optical axis. At each of discrete positions of the focal plane, a specimen is scanned with the electron beam. The resulting secondary electrons are detected by a detector. Individual output signals from the detector are compared to select the maximum signal. Then, only the objective lens is excited. The exciting current fed to the objective lens is modified to move the focal plane along the position closest to the specimen surface.

Abstract: A single aperture ion source is used to produce a ribbon shaped ion beam through which a targer may be transported. At an aperture of the ion source the ion beam converges in a vertical direction and diverges in a horizontal direction. The ion beam is passed through the poles of an analyzing magnet. A waist of the ion beam in the vertical direction occurs at the analyzing magnet. The analyzing magnet causes the ion beam to converge in the horizontal direction. Immediately before the ion beam strikes the target, the ion beam is passed through a focussing magnet which renders the ion beam trajectories substantially parallel. Between the ion source and the target, the ion beam may be passed through one or more resolving slits, as necessary, to trim the ion beam and assure that a focused, uniform beam reached the target. At the target, the analyzing magnet projects an inverted image of the aperture of the ion source.

Abstract: The invention relates to a process for the protection of a diaphragm during the generation of electron-beam pulses by means of alternately deflecting the electron beam onto the diaphragm and onto a processing site.In order to prevent damage to the diaphragm from the thermal effect of the electron beam, the electron beam is distributed with respect to space and/or time over an enlarged striking surface.

Abstract: A focus magnet having (a) three axially magnetized hollow cylindrical permanent magnets disposed concentrically along a center axis of a cathode ray tube such that their opposite magnetic poles face each other; (b) yokes in the form of hollow discs disposed on both sides of the permanent magnets; (c) a static control coil disposed inside a center permanent magnet; (d) a horizontal dynamic control coil disposed inside one of side permanent magnets; and (e) a vertical dynamic control coil disposed inside the other side permanent magnet, whereby electron beams passing in the cathode ray tube are converged to a small spot diameter.

Abstract: A correction system for a high resolution charged particle beam apparatus provided with two hexapoles enclosing a telescopic round-lens system with two lenses which are arranged so that outer focal points of the lenses are coincident with nodal points which coincide with center points of the hexapoles. An additional coma-free round-lens doublet is added for imaging a coma-free plane of a lens to be corrected into a center plane of a first hexapole of the system. For both round-lens doublets the spacing between of the two lenses preferably equals 2f, f being the focal length of each lens.

Abstract: A magnetic electron focusing lens including a first pole piece, from a back side of which low-energy electrons are injected, and a second pole piece located on a front side of the first pole piece. The first and second pole pieces are coupled to form a single magnetic circuit. The first pole piece is shaped to maximize the magnetic field at a its front side at a peak much closer to the first then to the second pole piece. The specimen is located between the first and second pole pieces near the peak of the magnetic field.

Abstract: An electron-optical system devised so as to generate a pseudoeparallel micro electron-beam converging at a converging angle of 1.times.10.sup.-3 radian. The system comprises a condenser lens assembly and an asymmetric objective lens whose smaller field gradient side is directed to the condenser lens assembly. In another electron-optical system achieved by modifying the above system, the converging angle of the electron beam is made variable with an additional objective lens inserted between the condenser lens assembly and the asymmetric objective lens. The conversion angle can be varied by varying the conversion powers of both the objective lenses.

Abstract: The Delta-Phi microlens consists of a first foil (3) of a metal or alloy from the group of transition metals and a second foil (4) of a metal or alloy from the group comprising the elements of IA or IIA groups of the periodic system of elements, the second foil (4) being coated onto one surface of said first foil (3). A hole (2) extends through both foils (3, 4) in precise alignment with the axis (6) of a sharply pointed tip (1) made of conductive material and placed at a distance of the order of 1 .mu.m from that surface of said first foil (3) opposite said second foil (4). With the first foil (3) connected to ground and a potential on the order of -30 V applied at said tip (1), at ultra-high vacuum conditions, a beam of low-energy electrons will have trajectories (5) deviated towards a focal point (7).

Abstract: A scanning electron microscope is disclosed in which an objective lens includes a first pole piece and a second pole piece. The first pole piece is provided with a hole through which an electron beam passes, and is disposed between an electron gun for emitting the electron beam and the second pole piece. The second pole piece has a planar portion on which a specimen is placed, and the second pole piece being mounted on a supporting block movable in a plane substantially perpendicular to the projecting direction of the electron beam.

Abstract: A method for irradiating a workpiece, such as a strand, by charged particle, e.g.

Abstract: An electrostatic multipole lens consisting of flat electrodes, a pair of rod-like electrodes, and means for applying potentials to these electrodes. Each of the flat electrodes takes the form of a flat plate. The flat electrodes are disposed along an equipotential plane in an electrostatic n-pole field in or near planes given by y=.+-.(tan(.pi./n))x, the planes intersecting each other at the Z axis. The flat electrodes are cut out in the vicinity of the Z axis. The rod-like electrodes have surfaces which approximate in shape to a second equipotential plane in the n-pole field. The rod-like electrodes are located on the X axis in a region which contains the Z axis and is located between the planes. The potentials applied to these two kinds of electrodes correspond to the equipotential planes associated with the electrodes. Since the lens essentially consists only of the flat electrodes and the rod-like electrodes, the structure is simple. The dimension of the lens taken along the Y axis can be shortened.

Abstract: A charged particle beam lithography system comprises a beam source of a charged particle beam, a beam shaping aperture for providing a predetermined cross section to the charged particle beam, a first focusing system for focusing the charged particle beam on a first crossover point located on the optical axis, a second focusing system provided between the first crossover point and an object for focusing the charged particle beam on a second crossover point located on the optical axis, a beam deflection system for deflecting the electron beam such that the beam is moved over the surface of the object, a stage for supporting the object, a mask provided in a vicinity of said first focusing system, and addressing system for selectively deflecting the charged particle beam such that the charged particle beam is passed through a selected aperture on the mask, wherein the addressing system comprises an electrostatic deflector for variable shaping of the charged particle beam and an electromagnetic deflector for defl

Abstract: A method of correcting astigmatism of a variable shaped beam uses a charged beam lithographic apparatus having a deflector for generating the shaped beam, a focus correction coil for adjusting a focus of the shaped beam, and astigmatism correction coils for correcting the astigmatism of the shaped beam.

Abstract: A charged particle beam apparatus comprising a particle source for generating a particle beam to irradiate a specimen located in a field space of a particle lens of the apparatus is provided with an auxiliary particle source for generating a particle beam of low energy particle to be injected into the lens field space and to be directed to the surface of the specimen by the same lens field.

Abstract: A deflection compensating device for a converging lens includes a first electrostatic deflector by which a charged particle beam is deflected to a desired position by applying an electrical field to the charged particle beam. An electromagnetic type converging lens is where the charged particle beam is converged by applying a magnetic field to a beam deflected by the first electrostatic deflector. A second electrostatic is disposed in a magnetic field generated by the converging lens and generates an electrical field in a direction deviated by 90.degree. with respect to the direction of the electrical field generated by the first electrostatic deflector. The passage way of the charged particle beam which passes through the electromagnetic type converging lens substantially corresponds to the lens center axis of the electromagnetic type lens.

Abstract: In a charged particle beam generating apparatus, the emitter is so arranged that its distal end is disposed at a level below a peak of a distribution of a magnetic flux density. An inner diameter of a lower portion of a pole piece is smaller than an inner diameter of an upper portion of the pole piece. The peak of the magnetic flux density is disposed close to the lower end of the pole piece, and at the same time the magnetic field is prevented from extending downwardly beyond the lower end of the pole piece.

Abstract: The lens is formed by the association of two electromagnetic lenses sharing one and the same magnetic circuit crossed by one and the same central channel. The first lens is a shielded lens and has an annular gap at one of its ends. This annular gap cuts the central channel along a direction the plane of which is perpendicular to the optical axis. The second lens is a single-pole lens surrounding the annular gap of the first lens. It has an annular gap demarcated by two lips, the walls of which have shapes generated by revolution around the optical axis. Induction coils enable the magnetic flux of the gaps to be made to vary.

Abstract: In order to utilize a magnet arrangement having a magnetic flux density field for beam guidance in the deflection of a beam of monopolar charged particles, regions of the field having curved field lines, are modified to significantly linearize the field lines in the area of the beam. An additional flux density field is superimposed on the primary flux density field so that the field lines interact in an harmonic synthesis and so that the field lines of the resulting field in the region of interest, extend linearly. In this way, the deflection force on the beam is essentially independent of the beam position in the field direction and in the linearized region.

Abstract: An electron microscope eliminates external ducting for evacuation by interlinking the interiors of a sample chamber for a sample, a casing for electron lenses and a chamber for an electron gun. Those interiors form a closed space with an evacuation path extending therethrough and are evacuated by evacuation means a vacuum pump connected to the sample chamber. The electron lenses are contained within sealed modules and the evacuation path passes between the sides of those modules and the internal walls of the casing. The resulting structure may be enclosed in substantially unbroken magnetic shielding.

Abstract: An unipolar magnetic field type objective lens used as an objective lens of an electron beam device. By properly adjusting the shape and strength of the objective lens, not only the aberration coefficients of the objective lens are reduced but also the secondary electrons emitted from a sample are efficiently detected to thereby allow semiconductor wafers of large diameter to be observed at a low acceleration voltage, a large angle of inclination, and with a high resolution.

Abstract: A process and a system are disclosed for controlling the focusing of a beam of monopolar charged particles which is used, for example, to vaporize substances in vacuum coating systems. The beam (S) has a cross-sectional area (Q) in a plane (E.sub.1) transverse to the axis of the beam. Perpendicular to plane (E.sub.1) there is a plane (E.sub.2), the surface normal (R) to which indicates the direction in which the change in the cross-sectional area (Q) is to occur. According to the invention, flux density fields (B.sub.1, B.sub.2) are applied, which are parallel on opposite sides to plane (E.sub.2) but have opposing directions. As a result, the change in the focusing of the beam has essentially no effect on any deflection of the beam; that is, it is possible to control the focusing without exerting any significant effect on the deflection.

Abstract: The multipole element has an even number of pole pieces (PS, PS') which are rranged symmetrically with respect to the optical axis (OA) of an electron beam measuring device and are rigidly connected to a ring-shaped yoke (J) by bar-shaped mounting elements (PH, PH'). A beam tube (SR), which is made from an electrically insulating material and has vacuum-tight ducts to receive the mounting elements (PH, PH') which are rigidly connected to the pole pieces (PS, PS'), is arranged coaxially with respect to the optical axis (OA) inside the yoke (J) which serves to guide the magnetic flux. The coils (SP, SP') for magnetic excitation of the pole pieces (PS, PS') are arranged on the parts of the mounting elements (PH, PH') lying outside the beam tube (SR). In order to generate an electrical multipole field suitable potentials (U, U') are applied to the pole pieces (PS, PS').

Abstract: A raster scan control system (18) for use with a charged-particle beam delivery system (20) provides precise control of large currents driving an inductive load. The beam delivery system includes a nozzle through which a charged-particle beam (24), such as a proton beam, passes prior to being directed to a target (32). The nozzle includes both fast and slow sweep scan electromagnets (204, 208) that cooperate to generate a sweeping magnetic field that steers the beam along a desired raster scan pattern at the target. The electromagnets are driven by large currents (213, 215) from the raster scan control system.

Abstract: A thermally stable magnetic deflection assembly for use in an electron or particle beam machine with several separately potted magnetic coils spaced apart and arranged in a particular vertical position on a central pipe. Non metallic, low coefficient of thermal expansion, highly thermally conductive materials are used throughout and means are provided for maintaining the entire assembly at a desired temperature. Also disclosed is a method of making a thermally stable magnetic deflection assembly.

Abstract: A high performance, vacuum compatible electromagnetic electron lens coil for electron beam systems has reduced gaseous emissions and improved heat dissipation capability. It comprises a wound coil of electrically conductive wire sheathed in a selected thermoplastic resin insulator. The wire insulator is coated with a hermetic layer of low vapor pressure metal. The low vapor pressure and hermetic sealing properties of the layer provide ultra high vacuum compatibility of the coil. The high thermal conduction property of the layer provides high heat dissipation capability and therefore permits high current densities in the coil.

Abstract: An objective lens in an electron microscope is adapted to detection of Auger electrons. Using an additional lens field, preferably including the use of a VAIL lens, the electrons to be detected are spiraled to a selection space. Between the lens field and the selection space a preferably displaceable, magnetic diaphragm is arranged for the separation of lens fields.

Abstract: In a scanning electron microscope scanning a specimen by an electron beam, the electron beam is two-dimensionally deflected so that a deflection fulcrum for the electron beam is located on the principal plane of an objective lens. Further, in order that the electron beam is incident on the specimen at a predetermined angle of incidence, the electron beam is deflected in a relation in which the object point of the objective lens provides another deflection fulcrum. The angle of incidence of the electron beam incident on the specimen is changed over between +.theta. and -.theta., thereby providing a pair of stereoscopic scanned images of the specimen.

Abstract: A Variable Axis Lens system comprises at least two lenses which are arranged to be radially offset with respect to an optical axis of the apparatus. Because the lenses do not contain iron, the occurrence of disturbing eddy currents can be prevented. The lenses for axis displacement are preferably constructed as single ring conductors, a number of which can be readily arranged in one plane in a partly overlapping fashion. Such a system can also be arranged behind the object. For the lenses for axis displacement use is preferably made of a ceramic superconducting material having a comparatively high temperature coefficient and a comparatively high specific heat in the superconducting phase, so that they can be simply cooled from the outside.

Abstract: An electron beam lithography apparatus having an external magnetic field correcting device comprises an electron gun for irradiating an electron beam onto a semiconductor wafer, a electron beam column made from a high magnetic permeability material disposed around the electron beam, a coil equipped on the electron beam column, a magnetic sensor for detecting an external magnetic field which is disposed at the outside of the electron beam column, a stage for mounting and moving the semiconductor wafer, a position detecting means for detecting the position mark on the stage, a correcting device for generating a correcting signal based on the outputs from the magnetic sensor and the position detecting means, and a current adjusting device for adjusting a correcting current flown into the coil according to the correcting signal from the correcting device so as to compensate a rotational deviation of the electron beam caused by the external magnetic field.

Abstract: There is disclosed an electron microscope having an auxiliary lens inserted between the final-stage focusing lens and a set of objective lenses. The microscope is further equipped with a circuit which varies the intensity of the auxiliary lens so as to fix the position of a crossover image irrespective of the intensity of the final-stage focusing lens. The crossover image is created between the auxiliary lens and the set of objective lenses by the auxiliary lens. An aperture plate having an objective aperture is disposed at the fixed position of the crossover image.

Abstract: The invention relates to an imaging corrector of the Wien type which is especially suitable for use in an electron microscope. The corrector includes an arrangement of at least eight electrodes and at least eight magnetic poles and is mounted between two electron lenses. The corrector simultaneously corrects the chromatic and spherical aberrations especially of electron lenses of low-voltage electron microscopes. The corrector begins and ends at intermediate image planes and has an intermediate image plane in its center. The intermediate image plane at the center coacts with two symmetry planes located between the intermediate image planes for the desired imaging characteristics. All chromatic and spherical aberrations for electrons of any desired energy can be corrected with two of the correctors coacting with a thick telescopic round lens disposed therebetween.