FREQUENCY HETERODYNING IN PHOTOMULTIPLIER TUBES

Photomultiplier tubes with a suitable electrode structure were investigated for use in a superheterodyne-type signal receiver for the Doppler shift laser velocimeter (LV). An oscillator signal impressed upon specially constructed electrodes within the photomultiplier tube produced a signal at a frequency which was the difference between the oscillator and the LV signal frequencies. The high gain of the photomultiplier tube then amplified the difference frequency signal to a usable level. Two different tubes were investigated and found to be useful as heterodyne photomultiplier tube amplifiers. The circuit design, experimental results, and applications are discussed. Prepared in cooperation with ARO, Inc., Tullahoma, Tenn.