A method for printing a desired periodic pattern, which includes providing a mask bearing a pattern of features having a period, providing a substrate bearing a photosensitive layer, arranging the substrate with a separation from the mask, generating collimated light with a wavelength and an intensity, at least the former of which may be temporally varied to deliver a spectral distribution of energy density, illuminating the mask pattern with said light whilst varying at least its wavelength so as to deliver a spectral distribution of energy density, such that the light-field transmitted by the mask is instantaneously composed of a range of transversal intensity distributions between Talbot planes, and whereby the layer is exposed to a time-integrated intensity distribution that prints the desired pattern, wherein the separation, spectral distribution and period are arranged so that the time-integrated intensity distribution corresponds to an average of the range of transversal intensity distributions.