We introduce a photometric ellipsometric method to determine the dielectric tensor of an optically uniaxial material suited for in-situ measurements. The technique employs a rotatable polarizer to provide a series of polarization states, eliminating the need for sample rotation or changes in angle of incidence. A method is presented that enables extraction of the dielectric tensor using standard rotating analyzer methods. As an example, the method is used to determine the indices of refraction and the orientation of principal axes for a calcite crystal.