Abstract: In the case of a deformable mirror (11) with a mirror plate (13) which is in glass form in particular for high laser frequencies and an axial actuator (20) which concentrically engages the rear side of the mirror surface (17)—with a reduced actuator stroke movement for the same dome-like configuration height—the dome configuration of the convex curvature of the mirror surface (17) is now of larger area and at the same time better approximated to the desirable sphere if, instead of the central application of force, the arrangement provides for decentral application of force at diametrally opposite locations. For that purpose the actuator (20) operates on a ring (25) which is disposed behind the mirror plate 13 and which is preferably integral with the mirror plate (13).

Abstract: In the case of a deformable mirror (11) with a mirror plate (13) which is in glass form in particular for high laser frequencies and an axial actuator (20) which concentrically engages the rear side of the mirror surface (17)-with a reduced actuator stroke movement for the same dome-like configuration height-the dome configuration of the convex curvature of the mirror surface (17) is now of larger area and at the same time better approximated to the desirable sphere if, instead of the central application of force, the arrangement provides for decentral application of force at diametrally opposite locations. For that purpose the actuator (20) operates on a ring (25) which is disposed behind the mirror plate 13 and which is preferably integral with the mirror plate (13). If the application of pressure to the rear side of the mirror plate (13) is not along a circular ring but a ring (25) which is of elliptical cross-section, then astigmatism effects are reliably avoided even with large angles of beam incidence.

Abstract: A deformable mirror for a laser beam material machining apparatus including a housing for supporting a mirror plate, an electro-mechanical actuator disposed within a jacket tube, a pressure portion disposed at one end of the actuator and a rear end adaptor with a prestressing screw at the other end of the actuator for operatively acting on the mirror plate. The materials of the jacket tube and the housing as well as the materials of the pressure portion and the rear end adaptor are so selected on the basis of their linear coefficients of thermal expansion, such that a temperature change will cause essentially similar overall linear expansion.