Heterodyne spectroscopy for submillimeter and far-infrared wavelengths from 100 μm to 500 μm

Heterodyne spectrometers having a resolving power of more than 106 for the wavelength range from 100 μm to 500 μm are described. Essentially the receiver consists of a Schottky barrier diode in an open structure mixer, an optically pumped molecular laser as local oscillator, low noise HEMT and FET amplifiers and an acousto optical spectrometer. Different applications of this type of receiver for remote observations in astronomy, atmospheric physics, molecular spectroscopy and plasma diagnostics are described.