Wolter telescope

As Wolter telescope is called an X-ray telescope that uses a mirror arrangement as the German physicist Hans Wolter proposed in 1952. This exploits that the refractive index of materials for X-rays is slightly less than one, thus occurs on the surfaces of total reflection at grazing incidence.

This mirror assembly consists of many nested metallic ( often made ​​of coated films existing ) paraboloid of revolution, which are each followed by a hyperboloid of revolution, together. Also spheroids are used in combination with paraboloid of revolution. These mirrors have together similar imaging characteristics as ordinary telescopes in the visible range of light.

Although already proposed in 1952, it took until 1978 until the first Woltertelskop for the X-ray satellites Einstein could be realized. This is due to the required extreme accuracy of the surfaces whose roughness may be only a few millionths of a millimeter.

Types of Wolter telescopes

Wolter type I and II consist of a combination of a paraboloid and a hyperboloid mirror system. In a Wolter -I system, the reflection always occurs in the insides of the mirror systems, wherein, in a Wolter - II system, the first reflection at the inner side of the parabolic mirror and the second reflection takes place at the outer side of the hyperboloidal mirror. The X-ray satellite XMM -Newton uses three Wolter - I systems, each with 57 nested mirrors.

Wolter type III systems reflect the X-ray photons, first at the outside of a paraboloid, which are then focused on the inside of the ellipsoidal mirror.