Device for trapping laser pulses in an optical delay line

Abstract

A device for maintaining a high-energy laser pulse within a recirculating optical delay line for a period time to optimize the interaction of the pulse with an electron beam pulse train comprising closely spaced electron micropulses. The delay line allows a single optical pulse to interact with many of the electron micropulses in a single electron beam macropulse in sequence and for the introduction of additional optical pulses to interact with the micropulses of additional electron beam macropulses. The device comprises a polarization-sensitive beam splitter for admitting an optical pulse to and ejecting it from the delay line according to its polarization state, a Pockels cell to control the polarization of the pulse within the delay line for the purpose of maintaining it within the delay line or ejecting it from the delay line, a pair of focusing mirrors positioned so that a collimated incoming optical pulse is focused by one of them to a focal point where the pulse interacts with the electron beam and then afterwards the pulse is recollimated by the second focusing mirror, and a timing device which synchronizes the introduction of the laser pulse into the optical delay line with the arrival of the electron macropulse at the delay line to ensure the interaction of the laser pulse with a prescribed number of electron micropulses in sequence. In a first embodiment of the invention, the principal optical elements are mounted with their axes collinear. In a second embodiment, all principal optical elements are mounted in the configuration of a ring.