System for detecting the contrast of high-power pulse laser radiation

A system for detecting the laser beam prepulses is described which has been elaborated for the Delfin laser thermonuclear synthesis facility. The results are presented of measuring the energy contrast of laser radiation, and the system is shown to be capable of measuring it in the range of 1 to 5x109. A technique of the oscillogram mathematical processing is suggested which allows to restore the laser pulse shape with the time resolution of the order of 1 ns at the maximum error <= 10%. The radiation detector used was a silicon photodiode with the following parameters: the reverse current of 0.2 to 2 μA; supply voltage of 20 to 120 V; the spectral range from 0.7 to 1.1 μm; the time resolution of the order of 10-8 s. The detector allows peak currents up to 1 A of several nanosecond duration