Interferogram Analysis.

Cumulative or destructive interference between two electromagnetic wave fronts arriving at a point and consequent occurrence of bright and dark bands or rings is a direct outcome of the wave nature of the propagation of electromagnetic energy. For the case of monochromatic wave fronts arriving at a point, the intensity of the radiation at the point in question can be shown to be a function of the Optical Path Difference. However, in order to obtain the pattern on a screen or in the focal plane of an optical detector, one has to make use of some optical elements. the only component which will contribute to effecting a change in the theoretically evaluated intensity pattern will be the lens system. The introduction of the lens system produces certain alterations in the pattern and these alterations are usually referred to as aberrations or, more particularly, the Seidel aberrations. An interforogram is a picture of an interference pattern and will always have all, or most of the aberrations present. An analytical study of an interferogram therefore is an approach to evaluate each of the aberrations in a photographed interferogram and use such evaluated information to detect the individual contributions of the various parameters which subscribe to the pattern. Author