Calibration methods and calibration systems of water-absorption-type high energy laser energy meters

Water-absorption-type high energy laser energy meters are widely applied to the energy measurement of high energy lasers for their high efficiency in the heat exchange. However, its calibration is a considerable difficulty for the absence of high power standard lasers. A calibration method for the high energy laser energy meter with the electric heating wires was introduced, and water was led into a heating container at the entrance of the absorption cavity. Then it is heated before flowing into the absorption cavity. The energy absorbed by the water flow was estimated and compared with the one measured by the energy meter to calibrate the energy meter. The conclusion can be drawn that the heat exchange modal of the calibration system is just the same with the one in the absorption cavity. They include two stages, in the first stage energy is stored and in the second stage the power reaches equivalent. The scattering of the flow and the gas has few effects on the measurement results, and the effects can be ignored after the results are calibrated. It can be concluded that the remaining energy and the flow rate have great effects on the measurement results and the effects caused by remaining energy on the measurement uncertainty can be efficiently decreased by increasing the volume of the reservoir. The measurement uncertainty was estimated at 4.8％(k=2) after it was calibrated, and the calibrated high energy laser energy meter was compared with the other measurement systems, yielding a calibration coefficient of 1.006 and a standard deviation of 1.4% (k=2).