Practical Lens Design

Riecke, W. D.

doi:10.1007/978-3-642-81516-4_4

Cited by 12 publications

(8 citation statements)

References 56 publications

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“…At that time, they were advocated as a way of overcoming power supply instability problems (Rieke 1982), but it soon became apparent that the field strength of permanent magnets was not strong enough for many common applications in electron optics.…”

Section: Permanent Magnetsmentioning

confidence: 99%

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A portable scanning electron microscope column design based on the use of permanent magnets

1998

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Summary:A portable scanning electron microscope (SEM) column design is presented which makes use of permanent magnets. Simulation results predict that such an SEM column is feasible and that it can be compact. The column height is typically less than 12 cm. The column is designed to be modular, so that it can fit onto a wide range of different specimen chamber types, and can also be readily replaced.

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Section: Permanent Magnetsmentioning

confidence: 99%

“…Since magnetic electron lenses have cylindrical symmetry, the two possible directions of magnetisation are in the longitudinal direction, parallel to the electron optic axis, or perpendicular to it, in the radial direction. Both possibilities have been advocated for electron optics applications (Adamec et al 1995, Rieke 1982.…”

Section: Permanent Magnetsmentioning

confidence: 99%

A portable scanning electron microscope column design based on the use of permanent magnets

1998

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“…For astigmatism correction, electromagnetic stigmators are used to provide a quadrupole field to correct the beam ellipticity (Riecke 1982). A typical octopole stigmator configuration is shown in Figure 4.…”

Section: Experimental Observationsmentioning

confidence: 99%

A robust focusing and astigmatism correction method for the scanning electron microscope

1997

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Summary: This paper discusses a new approach to focusing and astigmatism correction based on the fast fourier transforms (FFTs) of scanning electron microscopy (SEM) images. From the FFTs, it is possible to obtain information on the severity of the defocus and astigmatism. This information is then processed by an algorithm to perform real-time focusing and astigmatism correction on the SEM. The algorithm has been tested on defocused and astigmatic images of different samples, including those with highly directional features. Experiments show that the images obtained after running the algorithm can be as good as those that an experienced SEM operator can achieve.

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“…There are two primary factors that limit the response speed of a magnetic lens. The inductance of the lens coil winding limits the rate at which the excitation current can change (Riecke 1982). Typical values of inductance for SEM lenses range from a few hundred millihenries to several henries at low frequencies.…”

Section: Introductionmentioning

confidence: 99%

High‐speed operation of scanning electron microscope lenses

Thong

1997

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Summary:The speed at which the focal properties of an ironshrouded magnetic electron lens can be changed is fundamentally limited by Eddy currents in the magnetic material. The effects of such Eddy currents on the lens properties can be partially compensated by modifying the lens excitation to speed up the lens response. This work considers the application of excitation pre-emphasis techniques to scanning electron microscope lenses for small and large dynamic changes in excitation. Where transient material saturation effects come into play, attempts to further improve the lens response beyond that at the onset of saturation are futile. Under such circumstances, the use of a closed-loop feedback arrangement is proposed that can provide a degree of response improvement.

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Practical Lens Design

Cited by 12 publications

References 56 publications

A portable scanning electron microscope column design based on the use of permanent magnets

A portable scanning electron microscope column design based on the use of permanent magnets

A robust focusing and astigmatism correction method for the scanning electron microscope

High‐speed operation of scanning electron microscope lenses

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