Catadioptric System Definition and Applications

Catadioptric systems may be defined as optical systems that make use of lenses and mirrors for the formation of images. In other words, an optical system is one in which reflection and refraction occurs. Catadioptric systems are a combination of dioptric (lenses) and catoptric (mirrors) systems.

Catadioptric systems have been used in a number of optical systems since as early as the 1820s.

A true catadioptric system is one that consists of both reflective and refractive elements. A hybrid-catadioptric system, on the other hand, consists of a mirror telescope, along with a refractive field corrector. Catadioptric systems are used in telescopes and photography. Catadioptric systems are characterized by an unusually large field of view.

Components of a Catadioptric System

Catadioptric systems are devoid of aberrations, because the reflecting and refracting elements cancel out their aberrations. The lens and the mirrors of the system may be placed in the path of the incoming light, thus forming a full-aperture correcting system. When the lens is placed in the cone formed by the mirrors, the catadioptric system becomes a sub-aperture corrector.

Catadioptric Telescopes

Catadioptric telescopes are optical systems that combine specially shaped mirrors and lenses for the formation of images. Telescopes that are made up of such a combination tend to have an aberration-free large field of view, and an improved error correction.

Most catadioptric telescopes incorporate correctors in their design, so that the aberrations formed by mirrors and lenses are nullified. Catadioptric dialytes, full aperture correctors, and sub-aperture correctors are the different types of catadioptric telescopes.

Photographic Catadioptric Lenses

The catadioptric lenses used in cameras are called reflex or mirror lenses. Photographic catadioptric lenses incorporate the cassegrain concept for their design; this reduces the length of the optical assembly by a large extent. These photographic lenses come with some inherent drawbacks, such as inability to use an adjustable diaphragm, and fixed F-number of lenses.

Applications of Catadioptric Systems

Catadioptric systems are used in the following applications:

• Focussing systems, such as headlamps, lighthouses, and search lights
• Telephoto lenses
• Optical telescopes
• Microscopes

References

• Catadioptric Systems – Georgia State University
• Catadioptric Image Formation – Columbia University
• Designing Mirrors for Catadioptric systems that Minimize Image Errors – Columbia University
• Catadioptric Telescopes – Telescope Optics