Talbot effect for oblique angle of light propagation

The Talbot effect is investigated for oblique angles of illumination. From the transfer function of free space assuming small diffraction angles we calculate the self-imaging condition for periodic diffractive elements. Additionally, aberrations are considered, which are of third order in spatial frequency. These aberrations originate from the asymmetric off-axis configuration and cause distortions of the self-images. We include experimental verifications of our considerations and suggest applications of the off-axis Talbot effect to planar optics.