PT Journal AU Parvitte, B Thomas, X Courtois, D TI Wide band (2.5 GHz) infrared heterodyne spectrometer SO Int. J. Infrared and Millimeter Waves PY 1995 BP 1533 EP 1540 VL 16 IS 9 DI 10.1007/BF02274814 DE HgCdTe detector mixer ER