  We propose a simple and straightforward method to generate a spatially
variant lattice structures by optical interference lithography method. Using
this method, it is possible to independently vary the orientation and period of
the two-dimensional lattice. The method consists of two steps which are:
numerical synthesis of corresponding phase mask by employing a two-dimensional
integrated gradient calculations and experimental implementation of synthesized
phase mask by making use of a phase only spatial light modulator in an optical
4f Fourier filtering setup. As a working example, we provide the experimental
fabrication of a spatially variant square lattice structure which has the
possibility to guide a Gaussian beam through a 90{\deg} bend by photonic
crystal self-collimation phenomena. The method is digitally reconfigurable, is
completely scalable and could be extended to other kind of lattices as well.
