Low power lasers in physical therapy: measurement of optical output power of devices.

This report outlines the most essential characteristics of low power lasers commonly used in physical medicine. The optical output power of two Helium-Neon (HeNe) lasers (CW scanner) and two collimated Infrared (IR) laser diodes was measured with a CoherentR Model 212 meter designed to measure output power and its power density. The energy of two collimated IR lasers was measured with a Laser Precision Energy Meter equipped with an RJP-735 probe. The difficulties arising from the large divergence of the laser beam in diode lasers and the importance of the scattering and absorption of laser beams are discussed. The criteria for the evaluation of the lasers as well as the essential parameters for an adequate characterization of laser therapy are given.