| 摘要 |
The improved free electron laser device for scanning a spatial field is generally comprised of a drift tube and a rotatable mandrel. The mandrel is concentrically disposed in the tube so as to define an annular space therebetween. A series of canted mirrors of grooved-like configuration are formed about the mandrel in predetermined spaced relationship to each other and at a predetermined angle to a plane transverse of the mandrel. These mirrors function to reflect and phase redistribute various waves of the wave front so as to form a plurality of asymmetric diffraction patterns in the annular space. By reason of the nutating effect of the canted and rotating mirrors, the projected beam conically and continuously scans a region of the spatial field. In order to minimize the effect of skew waves, a series of circumferentially spaced and longitudinally extending rib-like baffles can be affixed to the tube interior between adjoining mirrors. In another embodiment, a series of longitudinally spaced mirrors of washer-like configuration are pivotally mounted on the mandrel for selectively projecting a laser beam at more than one angle to the device axis so that the beam conically scans more than one region of the field without moving the device itself.
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