Dialyte lens

Dialyt the catadioptric lens is a mirror - lens or telescope, which consists of at least two separated lenses, one of which is metallized, and therefore contains catoptric and dioptric elements. These systems have already been envisaged by Isaac Newton, but first published by Hamilton in 1814. In the meantime, a number of variants have been found to have a large field of view with low aberrations.

Hamilton

The Dialyt to Hamilton ( also Brachymedial ) consists of a front-side collecting lens of crown glass, followed by a spaced meniscus lens of flint glass, whose back is mirrored. Although many aberrations are well corrected, it has in this simple form to a strong lateral chromatism. Recent studies show that this can be significantly reduced with a correction lens near the focal point.

An auxiliary telescope according to this design, with 50 cm aperture and additional corrector is located in the observatory of Zvenigorod.

Schupmann

Main article: Schupmann medial telescope

The telescope towards the end of the 19th century, developed by Ludwig Schupmann and " medial " designated increases the distance between the mirror- meniscus lens, so that it is behind the focal point of the front lens. At the focal point, there is another converging lens - or a collecting mirror. By this construction, the lateral chromatism is avoided. However, the optical elements have to be tilted against each other, so that the image can be achieved, which results in other aberrations by itself.

A telescope with 30 cm aperture was tested in the years 1900-1901 in the Urania Observatory in Berlin; a version with a 38.5 cm opening in 1913 installed in the observatory of Landstuhl. Both telescopes were designed by Schupmann itself and contain a further correction lens directly in front of the mirrored meniscus lens: in the first variant of flint glass, in the later also widely available at the time of crown glass, from which also the lens is made. Schupmann also points to an alternative with only a meniscus lens of flint glass, but remained at the low chromatic aberrations.

Later Rathenower refractor with 70 cm - and 2002 was followed by the Swedish Solar Telescope with 1 m aperture.

Wiedemann - Busack - Riccardi - Honders

Systems in the Hamilton arrangement, but with the same types of glass for collecting lens and meniscus lens were further developed in various ways. E. Wiedemann designed around 1980, the "Astro Star", in which a compact size was achieved by a back-reflection at the plane side converging lens.

Hans -Jürgen Busack developed in 1998 and 2000, two variants, the former with front light emission, the latter in the Cassegrain arrangement; he also outlines a Schiefspiegler that avoids the central obstruction of the two arrangements.

These designs have the consequence that the converging lens designed to fail and an additional lens near the focus must be used. They have very low optical error, but on the other hand require very low tolerances of the optical elements and their adjustment to each other.

Systems by Klaas Honders and Massimo Riccardi offered as a telescope with 30 cm aperture and a field of view of 3 ° commercially.

Terebizh

Terebzh introduced in 2007 two variants of 50 and 100 cm aperture having a multi-element corrector near the focus. The designs of Terebizh distinguished in that the lenses are run at the light entry position after reflection from the Mangin mirror one more time before the corrector is achieved. Both have a flat, nearly diffraction-limited image with the former image field a of 7 °, and an opening ratio of 1:2, temptation. With a field of view of 10 ° and an aperture ratio of 1:1.7 The second variant, the excellent properties obtained by two lenses on the light incidence position.

Credentials

• A catadioptric telescope