Laser micro-machining is an increasingly important production method and is used in the automotive, aerospace, electronics, telecommunications and medical device industries. A variety of laser types are used in laser micro-machining and micro-ablation is the dominant mechanism for material removal. The laser types that are used in our lab include a multigas excimer laser and a Nd:YAG solid state laser with harmonic generators.

At UCSD, aerosol characterization techniques are studied to measure the quantity, size and momentum of the particulates in laser plumes. In addition, theoretical modeling of laser-material interactions, flow dynamics and the relevant vapor condensation, nucleation and growth phenomena are used to understand the basic mechanisms responsible for particulate production. This work is expected to add to the understanding of aerosol nucleation phenomena and the transition from plasma to supersaturated gas to particulate.

Particles condensed out of laser ablation plume vapor coupled with those released via hydrodynamic sputtering create problems in the production of microdevices utilizing laser machining techniques. These particles can unpredictably attenuate incident laser energy in subsequent pulses. Temporal and spatial energy intensity variations caused by the remnant particles of a previous plume are currently believed to be a source of significant process variability. Additionally, vapor condensation on the workpiece itself creates quality problems, which necessitate the use of secondary cleaning processes to achieve satisfactory quality levels.

Additionally, the presence of laser generated airborne particulates could also impact operation of an inertial fusion power plant. Airborne particulates interacting with incident laser radiation or deposited on mirrors and diagnostics could significantly impair the operation of these systems. In addition, the particulate has important safety implications; it could be radioactive, toxic and chemically reactive. Thus, characterization of the particulate in fusion systems is also needed to better understand the safety hazard and operational limits that such material could impose.

Particulate production is a broad area of aerosol science that has important industrial applications including for example cloud formation, pollution control, precipitation technologies, and production of nanophase material. In the Energy Technology Group Laser Lab, we are studying the formation and dynamics of these particles and their effects on incoming laser energy. This work helps to lay a basic research foundation supporting the optimization of pulsed laser ablation processing in microfabrication as well as the production of high quality nanoparticles.

Experimental studies of laser-material interactions is carried out in the Laser Plasma and Laser-Material Interactions Laboratory. The lab provides energy sources and diagnostics in support of the IFE Technology Program and for fundamental studies of laser-plasmas and laser-material interactions.

Affiliated research staff: