All scanning electron microscope-based inspection instruments, whether they are in a laboratory or on the production line, slowly lose their performance and then are no longer capable of providing as good quality, sharp images as before. Loss in image quality also means loss in measurement quality. Loss of performance is related to changes in the electron source, in the alignment of the electron-optical column, astigmatism, and sample and electron optical column contamination. Detecting a loss in image sharpness easily reveals this decrease of performance. Reference Material (RM) 8091 is intended primarily for routinely checking the performance of scanning electron microscopes. RM 8091 is designed for use in conjunction with Fourier analysis software such as the NIST/SPECTEL2 SEM Monitor Program, the NIST Kurtosis program, or the University of Tenesse SMART program. This RM is supplied as a small, approximately 2 mm x 2 mm diced semiconductor chip. RM 8091 is designed to be mounted onto a so-called drop-in wafer for specialized wafer inspection or dimensional metrology scanning electron microscopes or put on a specimen stub for insertion into laboratory scanning electron microscopes. This Reference Material is fully compatible with state-of-the-art integrated circuit technology.