<title>Evaluation Methods In The Design Stage Of Projection Lenses</title>

Abstract

The carrying out of special evaluations in the design stage of projection lenses is essential in order to make lenses exhibit target performance during practical use. For example, the resolution of a designed lens cannot be fully estimated by the calculation of MTF alone since MTF is calculated without concern for illumination conditions actually employed. In this paper, estimation methods of resolution and depth of focus of a designed lens by calculation of image contrast from image intensity distribution under actual illumi nation conditions are introduced. Next, consideration is given to the relation between chromatic aberration and image properties, namely to the connection between residual Chromatic aberration and image contrast, and to the connection between polychromatic exposure and image properties of resist. Finally, estimation of lens-to-lens distortion, another important performance factor of projection lenses, is attempted.