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Scope

1.1 This practice provides a reproducible means by which one aspect of the performance of a scanning electron microscope (SEM) may be characterized. The resolution of an SEM depends on many factors, some of which are electron beam voltage and current, lens aberrations, contrast in the specimen, and operator-instrument-material interaction. However, the resolution for any set of conditions is limited by the size of the electron beam. This size can be quantified through the measurement of an effective apparent edge sharpness for a number of materials, two of which are suggested. This practice requires an SEM with the capability to perform line-scan traces, for example, Y-deflection waveform generation, for the suggested materials. The range of SEM magnification at which this practice is of utility is from 1000 to 50 000 x. Higher magnifications may be attempted, but difficulty in making precise measurements can be expected.

1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. 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.

Significance and Use

The traditional resolution test of the SEM requires, as a first step, a photomicrograph of a fine particulate sample taken at a high magnification. The operator is required to measure a distance on the photomicrograph between two adjacent, but separate edges. These edges are usually less than one millimetre apart. Their image quality is often less than optimum limited by the S/N ratio of a beam with such a small diameter and low current. Operator judgment is dependent on the individual acuity of the person making the measurement and can vary significantly.

Use of this practice results in SEM electron beam size characterization which is significantly more reproducible than the traditional resolution test using a fine particulate sample.

Keywords

electron beam size; E 766; graphite fiber; magnification; NIST-SRM 2069B; resolution; SEM; SEM performance; spot size; waveform; ICS Number Code 31.120 (Electronic display devices); 37.020 (Optical equipment)

To find similar documents by ASTM Volume:

03.01 (Metals -- Mechanical Testing; Elevated and Low-Temperature Tests; Metallography)

To find similar documents by classification:

31.120 (Electronic display devices Including liquid crystal displays)

37.020 (Optical equipment Including microscopes, telescopes, binoculars, optical materials, optical components and optical systems Ophthalmic equipment, see 11.040.70 Optical measuring instruments, see 17.180.30 Photographic equipment lenses, see 37.040.10)

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