New linear multiplexed focal plane arrays have been developed for the AVIRIS (Airborne Visible and Infrared Imaging Spectrometer) instrument. The new arrays are designed to improve the AVIRIS mission placing emphasis on greater sensitivity and lower noise. An order of magnitude improvement in sensitivity is achieved primarily by use of a higher performance input circuit, and to a lesser degree, by maximizing detector photoresponse in region where the terrestrial signal is weakest. The silicon detectors were fabricated using a process that enhances their blue response, and the indium antimonide (InSb) detectors were fabricated with carefully selected spectral anti-reflection coatings. The multiplexer also incorporates a 'snapshot' mode eliminating the 'spectral smear' inherent with the previous design.