Researchers find world's first x-ray laser produces most coherent x-ray radiation ever

[Bosonic]

(PhysOrg.com) -- The world's first x-ray laser, the Linac Coherent Light Source (LCLS), first unveiled in 2009 at the Stanford Linear Accelerator Center in Palo Alto California, has been undergoing testing by group of physicists determined to find out how many of the photons it emits are synchronized and have found, as they describe in their paper in Physical Review Letters, the x-ray radiation that it produces, is the most coherent ever measured.

Following on the heels of the maser, invented in 1957, which was based on microwave radiation, researchers have searched for ways to make lasers with shorter and shorter wavelengths, with the hope being that coherence could be improved. Coherence is a measurement of how in-sync the photons in a laser beam are; the best laser would be one where all of the photons flow perfectly in sync with one anther, but of course, at least thus far, that’s not possible. This leaves researchers working to see how close they can get. The better or higher the coherence a laser has the more precise it can be diffracted which means it can be used to create sharper images of atomic structures.

To measure the coherence of the LCLS, the researchers shone the laser beam through two successive materials, each with a tiny hole in it, then measured the bands of dark and light produced on the other end; they found the contrast to be very high. Then by slowly increasing the size of the hole, they were able to see the interference introduced by those photons that were not in sync with the others causing a decrease in visibility. It is in measuring the decrease that the coherence of the beam can be measured. For the LCLS, it was shown to be 16.8 microns.

The team also tested the laser’s monochromatic abilities, which is a way of saying they measured the coherence time of the laser. The coherence time is the time interval that the wave is considered to be predictable. To do this they examined the edge patterns created when shooting the laser beam through the very tiny holes. For the LCLS they found the coherence time was 0.55 femtoseconds. The end result was that the majority (78%) of the photons were held within the confines the of the directed beam.

http://www.physorg.com/news/2011-10-world-x-ray-laser-coherent.html

[eppur_se_muova]

1. The generic term should be ERASER ...

Electromagnetic Radiation Amplification by Stimulated Emission of Radiation

[TheMadMonk]

2. T(erahertz)ASER (whoops), MASER, LASER, XASER, GASER

Hmmm, that one little octave right in the middle.

Let's just call them all LASERs and be done with it.

But sweet no matter what we call it. One more step along the way towards us growing up, or checking out in favour of the next candidate for dominant species.

Mix-n-match a compact and powerful enough wiggler with Plasma wave acceleration and an X-LASER carbine is within the bounds of possibility and a light vehicle portable weapon is inevitable.