An analytical solution of the optical Bloch equations for a degenerate two-level system is presented for coherent excitation with a monochromatic light pulse of rectangular time profile and linear polarization including off-resonance interaction. The generalization to an arbitrary excitation and detection geometry is achieved by incorporation of the appropriate coordinate frame rotations. In this way the formalism can be applied to the determination of alignment parameters in molecular ensembles even under partially saturated conditions. In the limit of linear absorption the results reduce to those obtained by Greene and Zare [J. Chem. Phys. 78, 6741 (1983)]. For complete saturation on lines of a Q or R branch, polarized fluorescence detection is sensitive only to the quadrupole alignment moment. The formalism also allows investigation of the production of aligned ensembles via coherent optical pumping with a single pulse. Depending on the degree of saturation as well as the detuning from resonance, strong alignment can be created.