High bandwidth multipoint fibre-optic vibrometer for transient measurements

We describe a laser vibrometer that is capable of making 256 simultaneous point measurements along a line. The ability to make simultaneous measurements is significant because in the case of multi-frequency or transient vibration modes it allows the measurement of vibration phase as well as vibration amplitude. For many applications such measurements cannot be obtained by any other means, and are of great interest to vibration engineers. In its present form, the vibrometer has a measurement bandwidth of 100 kHz, and measures displacements with a resolution of /spl lambda//25.