Back Scattered Electron Test Specimens

BSE Atomic Reference Specimen

Electron micrograph of the
nickel/copper backscattered
electron reference specimen.
BSE image at low magnification.
The contrast difference between
the two wires is visible due to
the atomic number difference
between the nickel/copper.

An electron microscope, when equipped with a backscattered electron detector, has the capability to produce images in which the contrast is controlled by differences in atomic number (Z) across the specimen. Four reference specimens are now available that are suitable for testing the atomic number contrast performance of a backscattered electron detection system.

Each of the reference specimens consists of two high purity elements that have an atomic number difference of 1. They are in the form of two wires embedded side by side in a contrasting matrix.

The specimens are available as a single mount either 3mm or 5mm diameter brass or aluminium tubes or alternatively can be incorporated into a block of standards.

Duplex Reference Specimen

An alternative and very sensitive test is by means of an alloy with two major copper/zinc phases separated by an atomic number difference of 0.1. The light phase illustrated in the micrograph has a mean atomic number of 29.47 and the dark phase a mean atomic number of 29.37.