Product Code: ICAL06_M605

Waterjet as a Multimode Waveguide - Theoretical and Experimental Investigation of Modal Noise and Beam Propagation in Material Processing with Lasermicrojet
Authors:
Bernold Richerzhagen, Synova SA; Ecublens Switzerland
Delphine Perrottet, Synova SA; Ecublens Switzerland
Joseph Battaglia, Sanova-USA; Santa Cruz CA USA
Tuan Anh Mai, Synova SA; Ecublens Switzerland
Presented at ICALEO 2006

Waterjets can be used as light waveguides due to the total internal reflection at the water-air interface. As the diameter of the jet is large compared to the laser wavelength, the jet is comparable to a multimode fiber. In this article the propagation and the intensity distribution of a laser beam coupled in a laminar waterjet at various coupling conditions such as jet diameter, velocity and jet length as well as beam numerical aperture and beam position from jet center is studied. The intensity distributions are also compared with the structures resulting from high power material ablation using the LaserMicroJet (LMJ) technology. The second part of this paper presents a study of heat affected zone after LMJ-processing of silicon at different wavelengths (1064 nm, 532 nm and 355 nm). Qualitative characteristics and microstructural changes were analysed with SEM, TEM and selective defect etching techniques. Three point bending fracture tests were conducted to determine the characteristic strength and the Weibull modulus of the silicon chips. The LMJ cut samples were also compared to samples separated using a conventional abrasive dicing saw.