Absolute Reference Calorimeter for Measuring High Power Laser Pulses

A calorimeter for making absolute energy measurements of high power laser pulses is described. The calorimeter, based on volume absorption in a solid, is calibrated electrically and requires no window or vacuum environment. An error analysis is included giving the systematic and random errors of the instrument for a laser measurement. Briefly, the following performance is typical of the 32-mm × 32-mm aperture calorimeter: range 0.4–15-J; random error ±0.2% (one standard deviation); systematic error ±2.3%; and an upper operational limit of 3 J/cm2. Most of the volume absorber documentation is applicable for 1.06 μm; however, the calorimeter should be useful from the near ir through the visible. Absorbers for use with CO2 lasers in the 9–11-μm range are also discussed.