The Optical Spectrum Analyzer Q 8341 (Advantest) uses a Michelson interferometer in a wavelength range of 350 to 1000 nm. The mechanical configuration of the interferometer allows a resolutions of 1 pm or 1 GHz in the frequency mode. This resolution as well as a measurement accuracy of 10 pm for interferometers of this size cannot be attained with monochromators, thus allowing accurate measurement of high-grade optical components. It also enables the world’s fastest measurement speed of 0.5 s. This highest resolution is particularly useful for the analysis of blue and blue-violet laser diodes, making the Q8341 an excellent choice for use in research on next-generation laser diodes and the increasingly smaller optical pick-ups.