The characterization of lithography tool performance during evaluation and in the production tool line is traditionally a time-consuming operation. The work presented here describes a technique which uses scattering of an optical probe from latent images in exposed, undeveloped resist to make rapid and reproducible measurements of a number of optical projection tool printing characteristics. Lens characteristics such as field curvature, astigmatism and coma as well as machine parameters such as column tip, focus and standard exposure dose may be measured. In addition, resolution and defocus sensitivity characteristics may be observed. Results have been obtained on exposure tools operating at various wavelengths and numerical apertures. The speed and accuracy of Latent Image Metrology (LIM) has enabled precise determination of exposure and barometric pressure induced focus variations. Changes in the field curvature, astigmatism and other imaging properties of lenses have been observed when they are subjected to high exposure doses.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.