In this paper we will analyze the propagation of the angular spectrum of the electromagnetic field through a finite length uniaxial crystal. We solve the boundary conditions of the fields at an interface of an isotropic medium and an uniaxial anisotropic medium with the optical axis in an arbitrary direction and soon after we choose the optical axis in a plane formed by the direction of propagation (z-axis) and the x-axis . We show how the couplings occur between the components of the field and in what situations we can give a vector or scalar treatment for the propagation. There is a considerable number of researchers working with the phenomenon of Spontaneous Parametric Down Conversion (SPDC). In most SPDC systems, the propagation of fields is neither orthogonal nor parallel to the optical axis. The calculations in this work are useful for this community. The results shown in the manuscript allow a precise evaluation of astigmatism as well as the walk-off for any phase match angle. So, I believe the results presented can be valuable for the SPDC community.