Modern Lens Design, 2nd Edition

Chapter 11Double-Meniscus Anastigmats

11.1 Meniscus Components

All anastigmats achieve a flat field by the longitudinal separation of positive and negative power (surface, element, or component power). The earliest anastigmats flattened the field by using a thick meniscus component, which separated the positive and negative outer surfaces. At the time there were no antireflection coatings, and designers tried to minimize the number of air-glass surfaces so that the surface reflections would not cause unacceptable ghost images or reduced contrast. For this reason, most of the early anastigmats were limited to two cemented meniscus components (with only four air-glass surfaces).

11.2 The Hypergon, Topogon, and Metrogon

The Hypergon lens of Fig. ...