1. The problem statement, all variables and given/known data Quartz is positive uniaxial crystal with ne (extraordinary axis) = 1.553 and no (ordinary axis) = 1.554. A) determine the retardation per mm at lambda (wavelength) when the crystal is oriented such that retardation is maximized. B) At what thickness(es) does the crystal act as a quarter wave retarder? 2. Relevant equations retardation (delta) = thickness (t) x (no-ne) retardation (delta) = (2pi * (no-ne) * thickness (t) ) / (wavelength) 3. The attempt at a solution A) retardation/thickness = no - ne B) t/delta = (2pi * wavelength * (no-ne) Am I using the right equations? I don't think so. What are they?