Abstract: A melting trough made of ceramic material is used for melting small amounts of metal by means of a flame including at least one trough channel which is not closed during operation. A thermosensor having a protective cover extends into the trough which is filled with melt during operation through an aperture in the wall of the trough. The aperture as well as the thermosensor are located below the level of the melt.

Abstract: An adjustment device for adjusting the reflector mirrors of a laser resonator to be precisely parallel to one another comprises a carrier and an integral adjustment head together having an H-cross section provided by a recess system of a peripheral outer recess flanked by a pair of inner circular recesses so that an axially elastic and adequately side stable and temperature permanent adjustment derives.

Abstract: For easy durable and safe fastening of an optical element (2) (e.g.: a reflector-mirror), without affecting ambient cleanliness, a cup-shaped frame (1) is provided, in whose depressed hollowed-out area (6) the optical element is embraced and thus laterally secured, while a spring leg (3) is provided as a fixing element, exerting a compressional force on the optical element. In this way, a threadless, cementless/plasterless fastening is realized. The invention is generally suitable for fastening optical elements, particularly a mirror or a totally reflecting prism of an optical resonator.