A photo detector is selectively coupled to a first integrator or a second integrator with switching circuitry when the laser pulses. An integration time of the signal from the photo detector can be substantially greater than an amount of time between successive laser beam pulses in order to provide an accurate measurement of each laser beam pulse of a high repetition rate pulsed laser. The laser may comprise a clock coupled to an optical switch of the laser system, and control circuitry can control switching and coupling of the detector to the first integrator or the second integrator in response to the clock signal. The first integrator and the second integrator can be selectively coupled to an output such that the first integrator or the second integrator is coupled to the output of the energy detection circuitry when the other integrator is coupled to the detector.