High accuracy laser power measurements: a scale comparison

Measurement scales for laser power and energy measurements using the C-series calorimeters, an electrically calibrated pyroelectric null radiometer, and a commercially available self-calibrating twin calorimeter system were compared at the 3-mW and 30-mW levels at 488 nm and 647.1 nm. Results show agreement in absolute measurements by these devices to within estimated uncertainties. A similar comparison at the 9-mW level of the argon UV laser lines (351.1 nm and 363.8 nm) showed agreement between measurements made by the C-series calorimeter and the electrically calibrated pyroelectric radiometer to within measurement uncertainties. A discrepancy of about 10% between these and the twin calorimeter measurements may be due to an uncorrected window transmission error in the latter.