Abstract: An optical system, for example a projection exposure apparatus for microlithography, has at least one optical element with an optical surface. A correction radiation device is provided that includes at least one correction radiation source for emitting correction radiation. A scanning device has at least one scanning mirror that is irradiated by the correction radiation and driven in such a way that a defined portion of the optical surface of the optical element is scanned with the correction radiation. This results in a correction of imaging characteristics of the optical element by means of heat which is supplied to the optical element by the correction radiation.

Abstract: An optical system, for example a projection exposure apparatus for microlithography, has at least one optical element with an optical surface. A correction radiation device is provided that includes at least one correction radiation source for emitting correction radiation. A scanning device has at least one scanning mirror that is irradiated by the correction radiation and driven in such a way that a defined portion of the optical surface of the optical element is scanned with the correction radiation. This results in a correction of imaging characteristics of the optical element by means of heat which is supplied to the optical element by the correction radiation.

Abstract: A method for joining a precious-metal section to an electrode of a spark plug is provide, the precious-metal section being joined to the electrode by means of heat input generated by a laser beam. The laser beam is applied to the precious-metal section and optionally also to the electrode. During the heat introduction, the laser beam covers substantially the entire surface of the precious-metal section. No relative movement occurs between the laser beam and the precious-metal section during the heat introduction.

Abstract: A process for manufacturing holes on the circumference of a hollow section situated in an internal high pressure forming tool uses the action of a punch integrated in the forming tool. A desired breaking point is formed on the hollow section, which follows the edge contour of the operating face of the punch; and after the withdrawal of the punch, the hollow section material surrounded by the desired breaking area, acted upon by internal high pressure, is extracted from the hollow section from the inside to the outside, forming a hole. In order to produce holes on the circumference of hollow sections, in which the shape of the outer circumference of the hollow section is maintained, the wall of the hollow section is weakened to form an unstable thin area. The punch penetrates into the wall of the hollow section at an internal high pressure which corresponds to the forming pressure for forming a hollow blank inserted in the forming tool.

Abstract: The invention relates to a process and apparatus and apparatus for manufacturing holes on the circumference of a hollow section situated in an internal high pressure forming tool, by the action of a punch integrated in the forming tool. A desired breaking point is formed on the hollow section, which follows the edge contour of the operating face of the punch; and after the withdrawal of the punch, the hollow section material surrounded by the desired breaking area, acted upon by internal high pressure, is extracted from the hollow section from the inside to the outside, forming a hole.

Abstract: A method and a device for producing holes in the circumference of a hollow shape, with a wall piece being separated as a slug from the hollow shape in an internal high-pressure mold and being jammed without projecting relative to the outer circumference of the hollow shape in a previously produced hole. In order to remove the slug produced during punching in simple fashion from the internal high-pressure mold, the separated slug is jammed at a fluid pressure that is reduced relative to an internal high fluid pressure without loss via a punch and can separate the slug following removal of the finished hollow shape from the internal high-pressure mold, from the hollow shape, finally clearing the hole.