A simple method for the acquisition of high-quality digital images from analog scanning electron microscopes

A method is described for converting video signals of analog scanning electron microscopes (SEMs) into digital images of high quality. A plug-in card commercially available for personal computers is used for the on-line analog/digital conversion. A Windows application program written by the authors, together with low-level software drivers supplied with the plug-in card, allow digital images to be recorded, to be displayed simultaneously on the computer monitor and to be saved as a file in a standardized format. Compared to conventional photographic images obtained from the SEM camera system, the digital images possess superior sharpness of outline, excellent image definition, diminished noise and well-defined grey-scale tones. This method provides SEM images of high quality for less than $1000 from most older analog SEMs. In addition, the advantages of digital image processing can be applied to analog SEMs, including contrast enhancement, digital filtering and multichannel recording.