  When light is incident upon a diffraction grating, images of the grating
appear at periodic intervals behind the grating. This phenomenon and the
associated self-imaging distance were named after Talbot who first observed
them in the nineteenth century. A century later, this effect held new surprises
with the discovery of sub-images at regular fractional distances of the Talbot
length. In this paper, we show that water waves enable one to observe the
Talbot effect in a classroom experiment. Quantitative measurements, of for
example the Talbot distances, can be performed with an easy to use digital
Schlieren method.
