Katadioptrilised

Katadioptrilised refers to a class of optical instruments that use a combination of lenses and mirrors to form an image. The term "katadioptrilised" is derived from the Greek words "kata" (down) and "dioptron" (through-sight), indicating a system that works by both reflecting and refracting light. These instruments are designed to overcome some of the limitations of purely refractive or purely reflective systems.

The primary advantage of katadioptrilised designs lies in their ability to achieve long focal lengths within a relatively compact physical volume. This is accomplished by folding the light path using mirrors, allowing the instrument to be shorter than a purely refractive telescope of equivalent magnification. They often employ a primary mirror to collect and focus light, and a secondary mirror or a lens system to further manipulate the light path. Corrective lenses are frequently incorporated to reduce optical aberrations such as chromatic aberration and spherical aberration, which can degrade image quality in simpler optical systems.

Examples of katadioptrilised instruments include the Schmidt-Cassegrain telescope and the Maksutov-Cassegrain telescope. These telescopes are popular among amateur astronomers due to their versatility, portability, and excellent optical performance for their size. They are capable of producing sharp, high-contrast images suitable for observing a wide range of celestial objects, from planets to deep-sky galaxies. The combination of refractive and reflective elements allows for a balance of performance and practicality.