Patent ID: 7103077

Claim:
An apparatus for measuring energy in an ultra-short pulse of a laser beam which comprises: a laser source for directing a laser beam along a beam path, wherein the laser beam includes a plurality of the ultra-short pulses, and each pulse has an energy; a photodiode for receiving a predetermined portion of the energy of each ultra-short pulse of the laser beam to generate a current therewith, wherein the current produces a voltage pulse indicative of the energy in a single laser pulse; an amplifier for amplifying the voltage pulse; an integrator for integrating the amplified voltage pulse over a specified time period to obtain an output signal, wherein the output signal is a measure of the energy of an ultra-short pulse from the laser beam; a rotating half-wave plate positioned on the beam path for establishing an orientation of the polarization of the laser beam; a polarizing beam splitter, optically aligned with said half-wave plate, for reflecting the predetermined portion of the energy of each ultra-short pulse toward said photodiode and for transmitting a remainder of the laser beam along the beam path; and a comparator for controlling the rotation of said half-wave plate.