Principles of High-Temperature Microscopy

An extensive summary of literature is presented which deals with (1) the design of microscope objectives suitable for high-temperature work, (2) the design of high-temperature microscope stages and furnaces, and (3) the problems of high-temperature photomicrography. Designs of microscope systems of long working distance and with numerical apertures of 0 or greater are available and have been shown to be suitable for studying microstructures at temperatures above 750° C. Numerical apertures as low as 0.1 are suitable for the observation of specimens in image-type furnaces and for the observation of macrostructures. Several types of excellent furnaces are available commercially.