LOW-COST VIBRATING REED MECHANICAL SPECTROMETER USING CAPACITIVE CURRENT DETECTION

Among the various mechanical spectrometers over the whole frequency do main, the vibrating reed system is an interesting variant owing to its convenient frequency range, the possibility of exciting additional vi bration modes and its ability to study thin films. In this paper a low cost set-up for such a vibrating reed spectrometer is described. The basic idea of this resonance-measuring system consists of a pulse trai n excitation of the specimen and a capacitive current detection of the freely decaying vibrations. Both the hardware and software concepts o f the system are described. An alternative numerical algorithm, based on a Hilbert transformation, to calculate the logarithmic decrement of a collected free decay is presented.