The application of colour to sem imaging for increased definition

Abstract

Definition in SEM images is enhanced by the inclusion of information obtained from different SEM detectors. This visual and technical information can be combined into a single image through the use of colour imaging. In the present technique three detector images are utilized to encompass the range in energy of electrons produced by scanning the sample. The back-scattered electron (BSE), secondary electron (SE) and low collector voltage secondary electron (LCV-SE) images provide material and topographic details in the final colour image. They are assigned to be red, green and blue primary colour components, respectively, which in the composite image, will provide a complete colour spectrum. Higher atomic number features appear bright in the BSE image and are easily observed as red areas of the colour image. Metal-coated samples show morphological details both from their topography (SE image) and from the non-uniformity of the metal coating (BSE image). Combinations of red and green, formed by these images, produce the earth colours expected with biological and mineralogical specimens. The LCV-SE signal, included as the blue image component, tends to highlight details favourably oriented towards the detector. Often this results in a differentiation between subject and background which aids in the illustration of a specimen. Many of the aesthenic qualities of a photograph taken with visible light are possible by applying the present technique to SEM imaging.