The Advantest Q8381A optical spectrum analyzer can analyze a wide wavelength band from 350 to 1750 nm and a wide dynamic range from -85 to +10 dBm (1.1 to 1.6 μm), accommodating measurements on display LEDs and optical devices for communication. In addition, ADVANTEST’s unique technology realizes low polarization dependence and a high level measurement accuracy of ± 1.5 dB. In addition to the automatic optimum measurement condition setting, automatic peak search and half-value width measurement functions, the Q8381A mounts the pulse light measuring function, power monitoring function and luminosity compensation display functions for improvement of operation and analysis capabilities. In conventional pulse light measurement, even if a number of averagings is made and the average power of duty ratio is obtained; low level and data missing may result. The Q8381A has solved all these problems.