Confocal

Geometry

In geometry, two confocal conics are called, if they have the same foci.

The set of all ellipses with the same focal forms a family of ellipses, in the cut, no ellipses. Likewise, no two hyperbolas intersect with the same foci. In contrast, a hyperbola intersects all confocal ellipses to always at right angles.

Optics

In optics is called optical systems two confocal, if they have a common focal point. This can, for example, the lighting and be the observation beam path of a confocal microscope or the concave end mirrors in a confocal laser resonator.