ONLINE THERMOCYCLES MEASUREMENTS IN LASER APPLICATIONS

The thermal state of material in the zone of laser action is one of th e main integrated parameters to determine the evolution of physicochem ical processes and structural phase transformations. The conditions of temperature measurements in laser machining are among the most severe even for noncontact technique of optical pyrometry. From a general po int of view, the absence of on-line control and monitoring is one of t he main limitations of laser technology integration into modem industr y. Data on surface temperature dynamics obtained by pyrometry could be widely used to: (a) understand and optimize the laser processes (i.e. define of the links between surface temperature history and the prope rties of treated materials); (b) create process control on-line includ ing feedback from a pyrometer. The main technical parameters of high s peed pyrometer (HSP) are the following brightness temperature range 11 50K(1550K)-3500K (threshold sensitivity depends on selected wavelength ); error of measurement 1%; response time 190 mus; 200 mum spatial res olution at 350 mm distance of pyrometer from the zone of temperature m easurements; wavelength variation in 2 colour channels from 0.5 to 1.1 mum. The opportunities of actual temperature measurements by high spe ed high spatial resolution pyrometer system in wide range of laser app lications are illustrated by : heat treatment, welding, cladding, and pulsed action.