Optical radiation describes the segment of electromagnetic radiation from λ = 100 nm to λ = 1 mm. Most lasers used in measurement instrumentation and fiber optic telecommunications systems work predominantly in the 200 to 1800 nm wavelength range. Because of the monochromatic emission spectrum and fixed output wavelength, detectors used to measure laser power do not need a radiometric broadband characteristic. This means that the typical spectral sensitivity characteristic of Si or InGaAs photodiodes can be used without requiring spectral correction. For absolute power measurements the bare detector’s spectral response can be calibrated at a single wavelength or over its complete spectral range. The corresponding calibration factor for that specific wavelength is selected when making the laser power measurement.
More information about monochromatic measurements can be found under:
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