The plane mirror is a mirror-coated on the front mirror , whose reflecting surface is flat, that is approximately an exact mathematical level corresponds. For practical cases, spherical surfaces with radii in the 10 km range are usually considered to be sufficiently flat.
Such mirrors are used in optical test setups (see optical bench ) to redirect light beams in another direction.
For such mirrors in optical structures, holders are required that are precisely defined to within 1 µm.
- Plain bearings are more defined than roller bearings .
- Threaded spindles allow adjustment.
- A mirror holder consists of a fixed bearing ( sapphire - ball in a hollow tetrahedron ), a movable bearing with a translational degree of freedom , a movable bearing with two translational degrees of freedom.
- A defined cardanic suspension consists of two stacked mirror holders.
- A defined linear system consists of two floating bearings with a degree of translational freedom on one rail and a third floating bearing on a second rail.
- A defined hexapod consists of a movable frame, a fixed frame and six legs. The legs are connected to the frame via fixed bearings . The legs consist of two parts that are connected to each other by a linear system . By releasing the spring, a component can be removed and precisely reset by tensioning.