A Korsch telescope is a three-mirror telescope with a wide field of view, whose design ensures that there is little stray light

Stray light

Stray light is light in an optical system, which was not intended in the design. The light may be from the intended source, but follow paths other than intended, or it may be from a source other than the intended source...

 in the focal plane. The design has a flat image plane, meaning that images on a flat detector will be the same size at the centre as at the edges.

The most famous observatory with a Korsch telescope is the planned James Webb Space Telescope

James Webb Space Telescope

The James Webb Space Telescope , previously known as Next Generation Space Telescope , is a planned next-generation space telescope, optimized for observations in the infrared. The main technical features are a large and very cold 6.5 meter diameter mirror, an observing position far from Earth,...

, though the design is also planned for the ESA high-resolution optical survey mission Euclid

Euclid (spacecraft)

Euclid is a planned space telescope, an M-class mission of the ESA Cosmic Vision 2020-2025, planned to be launched in 2019...

.