Experimental study of monitoring plasma light in laser cladding

Laser cladding monitoring is one of the cladding layer quality controlling methods. At present, cladding monitoring usually monitor the temperature or the shape of melting pool. The height deviation between melted and unmelted point is also considered. In this paper, optical signal of plasma which is one of the characteristic signal of plasma has been detected by phototube in cladding. The relationship between blue-violet light intensity and laser power scan velocity has been discussed, and the relevance between quality of layer and intensity has been analysed as well. The results indicate that while laser power growed the intensity increased just at a low rate, and the intensity decreased as scan velocity increased when the power is lower than a definite value. But when the power is greater than this value the intensity will rise as velocity increase. The quality of layer is improved greatly when the intensity value rang from 1.7 mu W/cm(2) to 2.5 mu W/cm(2) with a slight fluctuation.