B Babinet’s compensator Also known as Babinet-Soleil compensator. A device that can produce a continuous change in phase retardation between two orthogonally polarized beams of light. In this device, two quartz wedges — the slow direction in one being perpendicular to the slow direction in other — can be gradually slid against one another. The light passing through such a device suffers a retardation that is proportional to the distances in each wedge.