Diffraction--refraction corrector of the tertiary spectrum

This paper presents an analysis of the possibilities of rigorously superachromatizing optical systems by including a corrector in them that consists of a diffraction lens and two refraction lenses. A technique for choosing the glasses of the refraction lenses and determining the design parameters of the corrector is presented that simultaneously minimizes its Petzval curvature while superachromatizing the optical system. It is shown that combining a diffraction lens with refraction lenses in the corrector makes it possible to further substantially reduce the spherical aberration and spherical chromatism, as a result of which the polychromatic resolution of the system can be significantly enhanced both on the axis and over the entire angular field of the optical system.