Low Magnification Calibration Standards

Available for SEM and LM

Celestial Spheres

A mean size of 9.89µm polystyrene spheres are prepared under gravity-free conditions (Shuttle Columbia). In such conditions, exceptionally uniform spheres are obtained. These spheres can be dispersed over any specimen being examined to provide a reference standard (ASTM certified No. 1960). The size distribution is a narrow Gaussian with a standard deviation of 0.9% (excluding particles not on the main peak). There are some larger particles (less than 1% of the total) which can be excluded from measurement. A statistically significant number should therefore be measured.

Please note that the certificates covers mean size and does not carry a guarantee of size of any particular particle. Spheres are available in suspension or uncoated and dispersed on a silicon disc. (Disc to be mounted on a stub by user).

Silicon Test Specimen

This Test Specimen is made of a 5mmx5mm square of single crystal silicon. It is photo-etched and the squares repeat every 10µm. The dividing lines are 1.9µm wide.

A broader etching line is written every 500µm, which is useful in light microscopy. This is an excellent test specimen for comparing magnification and assessing any distortion in the image field. It is ideally useful in the context of automated counting systems to check for unsuspected distortions. Where critical measurements must be made the sample can be mounted directly onto the calibration specimen so that an internal calibration is obtained on the micro-graph.

Example Certificate of Calibration

SEM Calibration Specimens