Gold on Carbon Resolution Test on Short Pin Stub

This specimen has a particle size range from approximately 5 - 150nm. Each specimen has a square grid pattern with large crystals in the centre of each grid square and very fine crystals at the edges of each grid (as illustrated). Medium and high resolution point separation tests may be performed on the same specimen. In addition, the larger crystals show facets which allow an assessment of the grey level reproduction available at high resolution.

This calibration specimen provides a means of testing scanning electron microscopes. The various sizes of the gaps between gold crystals grown on a graphite substrate allow tests for the resolution attainable under real operating conditions: concomitantly, the samples canbe used to assess  the quality of grey-level reproduction at high resolution. Ideally, high resolution scanning microscopes should give good results in the gap test combined with good grey level reproduction. Medium-quality instruments may achieve a chosen gap resolution, but the grey-level production may be quite poor, for example, only 4 or 5 grey levels may appear. Grey levels arise in the secondary electron mode due to differential signal collection and this originates from geometric irregularities on the test specimen. Hence, the angular crystal faces in the larger gold crystals in this specimen can be used for the grey level assessment.