Unfiltered

Overview

In unfiltered mode, the intensity (magnitude) of the cathodoluminescence (CL) signal is measured. The measurement is integrated over all wavelengths, angles, and polarizations for a defined time interval.

Sometimes referred to as panchromatic, polychromatic, or black-and-white imaging.

Data collection

Unfiltered signal: The magnitude of the total CL signal (count rate or intensity) is measured using a light-sensitive detector such as a photomultiplier tube (PMT) or solid-state diode. The electron beam of the electron microscope may be continuously positioned at a defined location on the specimen (spot mode) or scanned rapidly over a defined area, and the measured CL signal is integrated over all locations.

Unfiltered map: The electron beam is scanned across the specimen surface, and the emitted light intensity is recorded at each location and displayed as a map.

Uses

Reveal texture in mineralogy, zonation, overgrowths, and micro-cracks; and reveal extended defects in semiconductor materials and devices.

Example of an unfiltered CL image showing the spatial variation in the integrated CL emission from an array of compound semiconductor micro rods.

Cathodoluminescence techniques for the geosciences