Efficiency of systems for pumping active elements of rectangular cross section

A calculation is given of the efficiency of a system for pumping an active element of rectangular cross section. Allowance is made for repeated re-emission of radiation passing through the illumination enclosure and absorbed by the flashlamp plasma. The correctness of the efficiency calculations is supported by experimental results. A proposal is made for a system which should increase considerably the laser efficiency compared with the pump systems used at present.