Applied Surface Science, Vol.252, No.13, 4472-4476, 2006
Surface temperature evolution in pulsed laser action of millisecond range
An originally developed multi-wavelength pyrometer (12 wavelengths in the range 1.001-1.573 mu m, 50 mu s acquisition time for each photodiode, 800 mu m spatial resolution, 900-3500 degrees C brightness temperature range) is used to measure brightness temperature under the pulsed action of Nd:YAG laser (HAAS-HL62P) on stainless steel (INOX 304L) substrates. Specially developed "notch" filters (10(-6) transparency at 1.06 mu m wavelength) are applied to avoid the influence of laser radiation on temperature measurements. The true temperature is restored on the basis of method of multi-colour pyrometry. The accuracy of brightness temperature measurements is examined by comparing the temperature evolution for pulses with different durations but with the same value of energy density flux. The influence of the following parameters is studied keeping the remaining ones constant: pulse duration (6-20 ms, rectangular pulse shape), energy per pulse (10-33 J, rectangular pulse shape), pulse shape (three types of triangulars and one rectangular). Finally the evolution of surface temperature for pulses with more complex shapes but with the same pulse duration and energy per pulse is compared. (c) 2005 Elsevier B.V All rights reserved.
Keywords:surface temperature measurements;multi-wavelength pyrometry;laser pulse shape;melting;solidification