Lens type optical equalizer for signal transmissions via multimode optical waveguides

Abstract From the Canadian patent

A lens type optical mode delay equalizer for multimode optical waveguides requires only two parallel lenses as equalizing elements, these lenses each having a cross section corresponding to that which would be formed by cutting away parts of two identical converging lenses by cuts parallel to their optical axes and, joining the remaining portions at the cuts. The parallel lenses are spaced between the ends of two lengths of waveguide in accosdance with a relationship involving various parameters of the lenses and the separation and maximum angle of propagation of the waveguide. Practical lens configurations may be toroidal or cushioncuspidal for circular waveguides and bicylindrical or …