Practical Measurements of Vibration Using the Moiré Effect

Displacement measurement is a critical issue in mechanical engineering. The moiré effect increases the accuracy of contactless measurements. We theoretically estimated the sensitivity threshold of moiré measurements using a digital camera on various objects. The estimated sensitivity threshold can be as low as a sub-pixel. We confirmed this experimentally in laboratory tests with a static image on a screen and simulated movement with non-integer and fractional amplitudes. We also provide practical examples of displacement measurement in the laboratory and outdoors (bridges and cars). Simultaneous measurements were made in two directions. The results can be used in public safety, in particular for monitoring the condition of engineering structures.