The development of the techniques and devices used to measure pulse laser output at the Air Force Weapons Laboratory is described. Included are discussions of principles, physical design, associated circuitry, and impedance- matching techniques. The instrumentation system consists of a total beam calorimeter suited to the laser energy range and an integrator whose signal is correlated to the calorimeter measurement. The calorimeter is either an absorbing surface or volume arranged so that the energy is well trapped. The surface absorber is a thermally isolated hollow silver sphere whose inner surface has been highly polished and whose heat capacity can be accurately calculated. The laser beam is admitted into the sphere at the focal point of a short-focal-length lens through a very small hole off center of the sphere. The volume absorber is cone-shaped as a result of various requirements and considerations. Thermistors or thermocouples are used to measure the resultant temperature rise. The use of these devices has several merits, chiefly high accuracy, stability, and relative simplicity. In addition, the devices lend themselves to the measurement of a wide range of energy densities; e.g., by variation of the diameter of the sphere in the first mentioned device. An entirely impedance-matched circuit was designed for the high-speed light- sampling diode. Several integration techniques were considered and three were selected; the one utilized depended on the experimental situation.