Noise tube sources for mm wave FT spectroscopy

Noise tubes in the wavelength region 6–4 mm, 3.3–2.1 mm and 2.1–1.36 mm are useful sources for millimeter wave Fourier Transform spectrometers. The output of the noise tubes has been adapted to the Michelson interferometer and the concentration optic of the pumped He cooled bolometer. Power comparison with the Mercury-Xenon lamp and power dependence of the noise tube on the driving currents has been studied. Plexiglas has been used as a long pass filter and the absorption coefficient measured.