Increasing the output power of laser systems is beneficial in a variety of applications, including directed energy and material processing. Measuring the power accurately and safely at high powers presents challenges that require consideration of such properties as cooling and light backscatter. In this session, Dr. Tim Cheng discusses issues in measuring high power laser systems as well as the methods and benefits of such techniques as beamsplitters, beam area expanders, volume absorbers, calorimeters, and more