Digital scanning of thin sections and peels

Abstract

ABSTRACT Digital film scanners allow direct capture of high-resolution digital images of entire petrographic thin sections or acetate peels, a capability not available using standard petrographic microscopes. Using a small-format, 35 mm film scanner as an example, this article describes a means of directly scanning, at high resolution, standard petrographic thin sections, larger (2 3 in.; 5.08 7.62 cm) thin sections, and portions of acetate peels and saving them as digital images. Such images fall into the range of macrophotography and bridge the gap between standard photography and photomicrography. Because no film is used and the light passes through no distorting lenses, the images obtained are of exceptional quality and can be processed and printed immediately. By sandwiching the thin section between sheet polarizing filters, scanned images through cross-polarized light can be obtained, simulating crossed nicols. The images of acetate peels far exceed the quality of equivalent photographs. Other film scanners and scanning film backs are available in large format and can be mounted directly on microscopes for digital imaging at higher magnification and can eliminate the need for conventional film in petrographic studies.