Adding a Maksutov-like corrector to a refractor apochromat improves the color correction of the apochromat

Abstract

After the more than six decades since D. D. Maksutov introduced his aplanatic, catadioptric camera with the meniscus corrector plate and spherical-mirror objective, the system and its variants are well familiar within the design community. But it would have achieved limited enthusiasm had it not been for the singlet corrector's propensity for achromatization, since no balancing aberration is available in the objective. However, the refractor-objective apochromat possesses balancing, chromatic residuals that may be coupled with a Maksutov-like corrector plate to provide improved correction for chromatic aberration. The combination may be further optimized to generate a chromatic error of longitudinal aberration that is only a small fraction of that of the progenitor refractor objective alone. Examples are provided with one and two corrector elements. Caveats are discussed.