The Soleil-Babinet Compensator is a continuously variable, zero-order retarder (waveplate) which operates over a broad wavelength range. The classical design of the compensator consists of a long birefringent wedge and a fixed wedge mounted to a compensator plate. The retardance is adjusted by moving the position of the long wedge relative to the short wedge using the precision digital micrometer. This allows the retardance to vary continuously while maintaining a uniform retardance across the aperture at any given setting.