Talbot interferometry with a vibrating phase object

We describe a Talbot interferometer for measuring a vibrating phase object. The time-average fringes are moiré patterns modulated by the zeroth-order Bessel function. They provide information about the tilt at every point of a vibrating plate, for example. The Talbot interferometer is robust (common path) and cheap (printers grids as beam-splitters). The experiments can be performed with laser illumination or with a collimated beam of white light. Some experimental results are shown.