Publications

Development and evaluation of an in-situ beam measurement for spot welding lasers

Fuerschbach, Phillip W.; Norris, J.T.; Dykhuizen, Ronald C.; Mahoney, Alan R.

A straightforward and accurate method for measuring the laser beam diameter at focus is desired in order to develop fundamental understanding and for routine process control. These measurements are useful for laser materials processing by assuring laser performance consistency at the workpiece. By employing multiple-shot exposures on Kapton™ film, an unambiguous and precise measurement of the focused Nd:YAG laser beam diameter for spot welding lasers was obtained. A comparison of focused beam measurements produced with the Prometec laserscope and an ISO variable aperture method found that these two methods, which both measure the 86% energy contour, do closely agree. In contrast, Kapton film was found to measure the 99% beam energy contour and to diverge from measurements made with the other two methods. The divergence between Kapton and the other two methods was shown to be due to changes in the laser irradiance distribution that do not affect the location of the 99% energy contour. Since the 86% beam diameter was seen to not always be representative of the true beam diameter, the 99% Kapton film diameter can provide a more representative measurement of the focused laser for in-situ process control.