More than 60 years ago, Hartmann' proposed a test procedure for the optical evaluation of large aperture astronomical objectives which remains to this day the principal tool by which astronomers accept or reject the claims of the manufacturer. Unfortunately, although relatively simple in application, astronomers have not always availed themselves of the Hartmann test, many indeed are ignorant of it, with the result that many have fallen heir to instruments of dubious or unknown quality. Noticeable exceptions to this situation have occurred in those cases where the astronomer has called for final shop testing based on Hartmann's method under controlled environmental conditions. For this and other reasons, American Optical has increasingly relied on the Hartmann test in the evaluation of large optical elements. Since 1961, American Optical has certified critical components on the basis of Hartmann tests . In fact, the standards of quality now expected of the optical industry require extensive Hartmann testing in the final stages of polishing. This allows the optician to bring the optical surface to a degree of perfection that exceeds his ability to evaluate by direct observation with the knife. Of course in situ tests of the objective remain the ultimate measure of the performance of an astronomical objective.