Inspection makes some noise

Steve Scheiber, Technical Editor -- Test & Measurement World, 8/1/2006

No one would contend—as some "experts" did 40 years ago—that lasers are an interesting curiosity with no practical application. Today, they drive everything from the telecom infrastructure to post-paste PCB solder-pad inspection. Yet, the recent announcement of the acoustic analog to lasers—sound amplification by stimulated emission of radiation, or SASER—is provoking a response similar to the one that first greeted lasers.

The technology has been around for several years, but a practical demonstration announced in Physical Review Letters (June 2, 2006) has brought the concept much closer to reality. SASERs produce coherent sound in packets of sound vibrations called phonons. The new version from Anthony Kent at the University of Nottingham and scientists at the Lashkarev Institute of Semiconductor Physics uses a superlattice of thin semiconductor layers to perform the amplification efficiently and economically. SASER wavelengths are in the nanometer range. One of the first proposed uses for the technology ("A Little Big Noise," The Economist, June 8, 2006) is for inspecting faults in microelectronic circuits.

It is easy to dismiss such developments as impractical and confined to the distant future. As with lasers, however, the future has a habit of catching up with us faster than we expect. Failure to anticipate it will inevitably leave us behind.

Contact Steve Scheiber at sscheiber@aol.com.