CONFERENCE REVIEW
Paula M. Noaker
ICALEO boasts laser chic and chatorlando, fl--Materials processing with ultrashort laser pulses (below 5 ps) was a major theme of several of the more than 200 papers presented at ICALEO `98, held here in mid-November. Other research topics discussed at the conference, sponsored by the Laser Institute of America, ranged from laser-surface ornamentation and rapid prototyping to microfabrication, diode-laser processing, surface processing, welding, and medical-device manufacturing.
The keynote address was given by Michael Perry, the associate program leader of the Laser Science and Technol- ogy program at Lawrence Livermore National Laboratory (Livermore, CA). Perry and colleagues pioneered ultrashort-pulse lasers for materials processing and developed the first industrialized femtosecond laser machine tool. He was thus the ideal candidate to describe how the cutting mechanisms eliminate thermal shock or collateral damage to allow precision machining to submicron tolerances. Weaving through this and other "ultrafast" presentations were questions related to whether the benefits of submicron machining can outweigh the costs that will be incurred in commercializing the technology, except in niche applications. A presentation by Xiangli Chen of GE Corporate R&D (Schenectady, NY) illustrating the prospects and challenges of commercialization attempted to answer the question "Short-pulsed laser machining: how short is short enough?"
In another session on the topic, Gerard Mourou of the University of Michigan (Ann Arbor, MI) discussed chirped pulse amplification and associated advances in femtosecond-pulse generation. Mourou explained the benefits of creating--with the same beam quality and laser energy--pulses ranging from nanoseconds to femtoseconds by simply adjusting the distance between grating pairs in a stretcher/compressor configuration. Perhaps this flexibility to adapt machining precision helps reduce the burden of the technology`s commercialization costs by broadening its potential application base.
A presentation of a quite different nature came from Anne-Marie Carey, an artist from the Jewellery Innovation Centre at the University of Central England (Birmingham, England). Her premise was laser-surface ornamentation--and exploring the boundaries of what qualifies as a good laser mark for the artist, instead of the engineer. Carey worked with researchers at the Department of Mechanical Engineer- ing at the University of Liverpool (Liverpool, England), as well as the Royal College of Art (London, England), to explore oxide thickness when marking titanium. Controlling this parameter allows control of the color produced on the work surface. Carey also explored the possibility of optically transferring a two-dimensional object image to a three-dimensional object, an example being a niobium bowl (see photo on p. 20). A point of interest was whether the effects of defocusing could be employed as an aesthetic quality. Also of note was the interest in this report by industrial participants at the conference. Engineers often forget that their products must sometimes be both well engineered and pleasing to the eye.
Engineers, especially those that have reached the lofty heights of management at North American automakers, also sometimes ignore the laser`s problem-solving capability. Illustrating this fact was an ICALEO presentation on "unfunded" research into surface alloying of silicon onto a low-cost 319 aluminum substrate. With this method, the project researchers estimate that automakers could save about 20 lb in vehicle curb weight by eliminating the cast-iron liners typically inserted in automotive engine blocks cast from aluminum. If this is true, the lack of interest in this research by automakers must be related to the low cost of gas in the USA and not to common sense.
Paula M. Noaker