Pulsed digital holography combined with laser vibrometry for 3D measurements of vibrating objects

摘要

An optoelectronic system is presented that is used to measure the 3D vector components of a vibrating object. The complete determination of the vibration occurs by combination of three different measurements. 1. A 3D system based on digital holography for the measurement of the 3D deformation vector along the directions x, y and z is used. Pulses from a ruby laser are used to record holograms on CCD sensors, which are later digitally reconstructed. 2. The shape of the object is determined. A ruby laser emitting two pulses with different wavelengths is used. The shape is obtained by subtraction of the phases of the wavefronts recorded at the two different wavelengths. 3. For the absolute measurement of a vibration using double exposure holographic techniques, it is necessary to have a reference point where the absolute vibration is known. This measurement is done by using a 3D laser vibrometer.