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#Mon Aug 09 11:52:47 CEST 2010
Slide__29do8KObEd-WfYQ0GneCwQ_title=SASE Principle of the Free Electron Laser (FEL)
Slide__29do8KObEd-WfYQ0GneCwQ_subTitle=Photons leak undisciplined through each crack, but they may also "laser" in a perfect harmony - thanks to <i>induced</i> emission found by Einstein in 1916\: An electron <i>bound</i> within the atom is stimulated by a photon to emit another, identical photon. <p></p> <p>A laser that rests upon <i>free</i> electrons (FEL) exploits as acceleration - that bears photons <i>spontaneously</i> - a slalom route enforced by magnets (figure). The emitted light ray may be amplified between two mirrors, as with the 'normal' laser.</p> <p><b>The advantage\:</b> In the FEL the laser frequency can be continuously changed. <b>The problem\:</b> There are no suitable mirrors for Roentgen light. <b>The trick\:</b> Magnetic structure, velocity and wavelength are tuned in a way that the self-amplification builds up already en route - the 'electron disks' follow one another with precisely a light wavelength distance and do permanently emit further such photons ... SASE ("Self Amplified Spontaneous Emission") is a completely new laser principle.</p>
Slide__29do8KObEd-WfYQ0GneCwQ_footer=Source\: Deutsches Elektronen-Synchrotron DESY