Are optical power meters and spectrum analyzers the same

A spectrum analyzer measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. The primary use is to measure the power of the spectrum of known and unknown signals. The input signal that most common spectrum analyzers measure is electrical; however, compositions of other signals, such as acoustic pressure waves and optical light waves, can be considered through the use of an appropriate. Spectrum analyzers for other. [pdf]