title: Optical sensor to monitor and control temperature and build height of the laser direct-casting process.
abstract: A nonintrusive optical sensor system is applied to real-time process control of the recently developed laser direct-casting process, in which a stream of metal powder is introduced into the beam of a high-power (500-W) cw laser to fabricate complex three-dimensional structures. The sensor system allows two critical parameters, temperature and build height, associated with this process to be monitored and controlled continuously. We achieved a height-sensing resolution of ?0.25 mm and temperature control with a resolution of ?10 degrees C at a typical working temperature of 1500 degrees C with an evident improvement in process quality, especially for complex workpieces comprising relatively high, thin walls at which the conductive heat transfer varies substantially as the process proceeds.
authors.forename: M D
authors.initials: MD
authors.lastname: Fox
authors.forename: D P
authors.initials: DP
authors.lastname: Hand
authors.forename: D
authors.initials: D
authors.lastname: Su
authors.forename: J D
authors.initials: JD
authors.lastname: Jones
authors.forename: S A
authors.initials: SA
authors.lastname: Morgan
authors.forename: M A
authors.initials: MA
authors.lastname: McLean
authors.forename: W M
authors.initials: WM
authors.lastname: Steen