An optically swept slab laser

A novel form of laser is described in which the beam is swept successively down the different sections of a slab of laser glass that form an amplifier chain. Diaphragms in the constant path section of the system force operation in the TEM
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mode while a grid of glass fibers down the slab gives a shortening of the pulse: half-widths of 2.9-80 ns depending on the number of grids. Absence of depletion effects in the laser medium until the last few stages makes the pulse length independent of the laser power, which is itself limited only by depletion of the stored energy and the beam area, up to 100 MW in the present design. The operational difficulties found in practice are discussed together with possible means of improving the system to give a wider range of pulse lengths and peak powers.