An optical power meter (or laser powermeter) is an instrument for the measurement of the optical power (the delivered energy per unit time) in a light beam, for example a laser beam. Typically, it allows for power measurements only with a relatively low bandwidth, and will e.g. display only the average power when receiving a pulse train with a high pulse repetition rate, e.g. from a Q-switched or mode-locked laser. For measuring pulse energies, there are other instruments, called optical energy meters.