Coherent Light
For almost 50 years, if you wanted coherent light, it was lasers and free-electron lasers. Now table salt has been added to this list.
Science Daily has the news about some ground-breaking work being done at
Lawrence Livermore National Laboratory:
Livermore Researchers Find New Source Of Coherent Light
With the exception of lasers and free-electron lasers, there hasn’t been another fundamental way to produce coherent light for close to 50 years.
But a group of researchers from Lawrence Livermore National Laboratory and the Massachusetts Institute of Technology have found a new source of coherent optical radiation that is distinct from lasers and free-electron lasers.
Applications for this research are numerous, but the most immediate result may be a new diagnostic tool to determine the properties of shock waves, said Evan Reed, an E.O. Lawrence postdoctoral fellow at Lawrence Livermore and lead author of a paper that appears in the Jan. 13 edition of Physical Review Letters.
Through a series of theoretical calculations and experimental simulations, scientists generated a mechanical shock wave inside a dielectric crystalline material, in this case kitchen salt (NaCl). One might expect to see only incoherent photons and sparks from the shocked crystal.
But what they found was so much more. Weak yet measurable coherent light was seen emerging from the crystal. The emission frequencies are determined by the shock speed and the lattice make-up of the crystal.
The team found that measurable coherent light can be observed emerging from the crystal in the range of 1 to 100 terahertz (THz).
"To our knowledge, coherent light never has been seen before from shock waves propagating through crystals because a shocked crystal is not an obvious source to look for coherent radiation," Reed said. "The light and radiation was in a portion of the electromagnetic spectrum that is not usually observed in these types of experiments."
There all along, nobody thought to look before. I can see a number of uses for this right off the bat -- the technology is going to get better. Imagine a small chemical analysis system powered by something similar to the piezo fire starter in a lighter or barbecue. Cheap ways to analyze motion and impact. The list goes on...
Posted by DaveH at January 16, 2006 7:49 PM