Holographic interferometry using an object-related reference

Holographic Interferometry with cw-lasers for vibration analysis of mechanical structures requires a stable platform for the optical set-up and the test object. To reduce this expenditure an interferometer was set up where the reference beam is directed onto the object. Changing the location of the reference spot on the object permits the determination of relative phases of different vibration centers. A first quantitative evalusation of time-average holograms yields the phase-correct vibration shape.