This generation of out of focus plane "hot spots" bears some resemblance to the well-known Talbot effect which can lead to periodic repetitions of an image of the spot pattern at regular distances away from the focal plane, the first layer being shifted by half the period of the focal spot pattern . The Talbot effect has already been used for patterning and 3D printing applications such as displacement Talbot lithography or proximity field nanopatterning . However, the Talbot effect generally occurs when all the spots in a regular array have the same light field phase. This is not the case with the DOEs used here since they generate spots with random light field phases and are therefore likely to produce random interference patterns due to overlap in out of focus planes.