The effects of astigmatism, angular misalignments and ghost reflections in a Michelson interferometer

Ghost reflections may degrade the performance of optical systems. In incoherent imaging systems, ghost reflections may cause contrast reduction and in severe cases may veil parts of the nominal scene. In coherent imaging systems, ghost reflections may cause spurious interference effects that may superimpose on the nominal scene. In this paper, the combined effect of angular misalignments, astigmatism, and ghost reflections on the performance of a Michelson interferometer are studied. To achieve this goal, a new analytical theory for the formation of fringes by a Michelson interferometer is presented. This theory is based on applying the basic concepts of ray tracing and wave optics approaches. A methodology to generate the possible ghost layouts in a Michelson interferometer is introduced. This methodology is based on decomposing the layout into nominal and ghost layouts. For each possible layout, a base ray is defined and is traced sequentially throughout it. Expressions for the amplitude and phase of the associated tangential and sagittal wavefronts are derived and are used to construct the effective electric field. At the detector, the nominal and ghost electric fields are added coherently. Analytical criteria for deducing the possible shapes of the nominal fringes are introduced. Simulation examples are provided and discussed.