Abstract: A system for measuring the energy of an ultra-short pulse in a laser beam includes a half-wave plate for orienting the polarization of the beam. A polarizing beam splitter is used to reflect a portion of each pulse of the beam and a remainder of the beam is transmitted toward a target. Energy in the reflected portion is measured by a laser energy meter (“LEM”) to determine the energy in the remainder of the beam. An output signal from the LEM is used to obtain an error signal that can then be used to rotate the half-wave plate to control the energy level in the remainder of the beam. In an alternate embodiment, a fixed-ratio beam splitter and a second LEM are used to measure and control the energy in the remainder of the laser beam.

Abstract: A system for measuring the energy of an ultra-short pulse in a laser beam includes a half-wave plate for orienting the polarization of the beam. A polarizing beam splitter is used to reflect a portion of each pulse of the beam and a remainder of the beam is transmitted toward a target. Energy in the reflected portion is measured by a laser energy meter (“LEM”) to determine the energy in the remainder of the beam. An output signal from the LEM is used to obtain an error signal that can then be used to rotate the half-wave plate to control the energy level in the remainder of the beam. In an alternate embodiment, a fixed-ratio beam splitter and a second LEM are used to measure and control the energy in the remainder of the laser beam.