A SIMPLE AND ACCURATE CONTACTLESS FREQUENCY AND AMPLITUDE METER

This study describes a measuring instrument based on the Michelson int erferometer. It is able to measure the amplitude-time function or the resonance curve in a wide frequency range simultaneously depending on the amplitude of the vibration without any kind of mechanical contacts . Compared with other instruments based on similar principles, it has the advantage of not being a heterodyne interferometer, that is of usi ng only the phenomenon of classic interference instead of the frequenc y of Doppler shift of the reflected light. The reflective surface of t he oscillating object or the mirror glued thereon may turn, which is o ften the case. The software performs a-correction to the errors arisin g from the turning of he mirror. In the realized instrument the allowe d maximum angle of rotation of the mirror is +/- 5 degrees, measuring range of the amplitude is 5 micron to 1 mm, measuring range of the fre quency is 1 Hz to 5 x 10(4) Hz depending on the amplitude. (C) 1997 Am erican Institute of Physics.