L1-A

MEASUREMENT OF LASER OUTPUTS
In all laser applications the laser that is chosen must have certain output characteristics determined by the application. To ensure that the laser does in fact meet required specifications, it is necessary to measure the laser output characteristics. The most common measurements are of the power of CW lasers, pulse duration and energy of pulsed lasers, and beam divergence.
Power Meters and Their Applications
Optical power meters are used to measure the power from a CW laser. They are commercially available for use at all laser wavelengths and for power ranges from nanowatts to kilowatts. All power meters contain the four basic elements shown in Figure 1. Light striking the detector results in a current flow through the detector. The amplitude of the current is proportional to the total optical power striking the detector for power within the detector design range. This current is amplified and used to drive the meter readout device. This may be a microammeter or a digital display. The power range of the meter normally is selected with a range switch that controls the gain of the internal amplifier.