1. The problem statement, all variables and given/known data A Mooney rhomb is a quadrilateral prism that converts linear light to circular polarized light. The question is here: Fowles', Google Books 2. Relevant equations Trigonometry. Snell's law. 3. The attempt at a solution Total internal reflection must occur at the edge of the rhomb. The total phase change due to TIR must be pi/4. But there are too many equations, and too few constraints!