A device for measuring optical power simultaneously for two or more spectral regions. Two or more photodetectors, such as photodiodes, measure the pulse energy and/or power emitted by a laser having output in two or more spectral regions. The laser radiation is transmitted through a diffuser or beamsplitter, then filtered and/or attenuated so that light from each respective spectral region is incident on the active region of a photodiode. The device also includes electronic circuitry with one or more operational amplifiers for each photodiode, integrators and analog-to-digital converters. In a preferred embodiment, the device also includes a microprocessor to provide noise reduction and calibration functions for each photodiode output, and to drive a display or readout.