Wave-optical formulation of the image-rotation property in Dove prisms: A Fourier-optics approach
In this paper, we present a formula for calculating the complex amplitude of the output electric field for a given input wave that impinges on a Dove prism. We use Fourier optics to decompose the input wave into plane waves, then find the output plane waves of the Dove prism as functions of the input spatial frequencies. The total output image is then obtained by integrating over all the output plane waves, resulting in a final formula in integral form. Since we conduct a wave-optical analysis for beam propagation and each incidence on Dove prism surfaces, all the physical aspects of electromagnetic waves are involved, including polarization, Fresnel losses, wave interference, phase, and intensity. The formula also explains why a rotated Dove prism rotates its input image twice its rotation angle. In addition, the formula is not limited to paraxial beams, as we find the Dove prism output as a function of the input Fourier components in general, without limiting the input spatial frequencies to small values. This generality is especially relevant for emerging applications that rely on non-paraxial beams, such as structured light generation, orbital angular momentum systems, and quantum imaging. However, since in most cases the paraxial approximation is valid and sufficient, a simplified formula is also extracted for paraxial beams. Two ray-tracing simulations are conducted to demonstrate the correctness and accuracy of our simplified formula. All the advantages mentioned make our derivation accurate, complete, comprehensive, and, to the best of our knowledge, the first to wave-optically prove the rotational feature of a Dove prism.