These detectors are composed of a linear strip of 512 or 1024 photodiodes, sensitive elements cooled by the Pelletier effect (thermoelectric effect). Combined with a spectrometer and a rapid digital reading system, this multichannel detector measures an entire light spectrum in a few milliseconds. Their development revolutionized the world of spectroscopy and accelerated the development of 2D detectors (CCDs), paving the way for spectroscopic imaging.