Fast nondamageable laser-pulse detector using gaseous plasma

Abstract

We investigated pulsed laser radiation detectors in which the emf is generated by the plasma formed when the radiation is focused onto a solid metal surface. We report on measurements made with 10.6-μn laser pulses at peak power levels up to 100 MW. For an evacuated detector, we obtained signals ≳1 kV and subnanosecond rise times into a 50-Ω load. Detector performance is strongly modified with the introduction of a background gas. With one atmosphere of air, the detector produces signals on the order of 1 V and nanosecond response for pulse trains lasting 100 ns, and is thus a good qualitative beam monitor. With argon, krypton, or xenon at pressures on the order of 10 Torr, the detector generates ’’trigger pulses’’ of 250-V amplitude and <0.2-ns rise times. These detectors are indestructable.