Abstract: An optical sensor for the monitoring of combustion processes in a combustion chamber comprises a lens system facing the combustion chamber, a waveguide and a sheath surrounding the lens system. The lens system has at least one essentially plano-concave lens and a double concave lens wherein the planar surface of the plano-concave lens is exposed to the combustion chamber. A method for centering one or more lenses and a waveguide in a sheath of an optical sensor for monitoring combustion processes in a combustion chamber is also disclosed that includes filling the gap between the first lens and the sheath with a soldering paste.

Abstract: The present invention relates to an optical sensor for the monitoring of combustion processes in a combustion chamber wherein the optical sensor at least comprises a lens system facing the combustion chamber, a waveguide and a sheath surrounding the lens system and one end of the waveguide characterized in that the lens system consists of at least one essentially plano-concave lens and a double concave lens wherein the planar surface of the plano-concave lens is exposed to the combustion chamber. The invention also relates to a method for the manufacture of said sensor.

Abstract: A method for moving a guide head of a wire erosion machine and possibly a workpiece along a guide path (TD), determining a drag error (S; S.sub.B ; S.sub.G) of a wire electrode from making several drag error acquisitions or from a combination of several drag errors (S; S.sub.B ; S.sub.G). Each drag error (S; S.sub.B ; S.sub.G) is determined during one drag error acquisition. Also, a wire erosion machine is disclosed with an actuating device for effecting movements of at least a guide head and/or a workpiece, along a guide path (TD) including with several devices for determining a drag error (S; S.sub.B ; S.sub.G) and a selection device for selecting the drag error (S; S.sub.B ; S.sub.G) from one device or from a combination of drag errors (S; S.sub.B ; S.sub.G) determined from several devices.

Abstract: The wire electrode advances upstream of the workpiece by a torus shaped wire guide with a position sensor to monitor the position of the wire electrode. Additional open v-grooved wire guides may also be present.