多年来，光学研究人员的一个目标是在现有其它光源很弱发射的波长上产生相干辐射。自由电子激光器（ＦＥＬ）迅速填补了较普通光源留下的电磁波谱空白。由于自由电子激光器能产生高峰值功率和高平均功率以及波长的可调谐性，它是很诱人的。与普通激光器相比，自由电子激光... Over the years, one goal of optical researchers has been to produce coherent radiation at wavelengths that are otherwise weakly emitted by other existing light sources. Free-electron lasers (FELs) quickly fill the electromagnetic spectrum gaps left behind by conventional light sources. Free-electron lasers are attractive because of their high peak power and high average power, as well as wavelength tunability. Compared with the ordinary laser, free electron laser ...