Numerical Calculation of Shapes Machined with Pulsed YAG Laser (1st Report)

Oscillation Characteristi and the Quantification

Abstract

It is generally difficult to estimate shapes machined with laser beam analytically, because many complicated phenomena break out in machining, such as phase change, generation of plume, characteristics change of material. So, in this series, it is tried by numerical calculation to predict shapes machined with laser beam. In this case, important matters are quantification of output characteristics of oscillator, detailed observation of machining phenomena and construction of machining mechanism. In this paper, the characteristics of used laser beam are investigated which show the sharpness of tool in material processing with laser. Namely, the oscillated wave form, the beam profile and the beam divergence angle are measured of normal pulsed YAG laser. The oscillated wave form is shown as a train of rectangles in a short time. The half angle of beam divergence is 2-3 mrad in the oscillator and it shows about ten times of the value calculated with diffraction theory. The beam profile is approximately shown by Gaussian distribution whose skirt is cut with the beam diameter.