A prescription for transforming polarization states of light using two   quarter waveplates
  It is well known that state transformation from one polarization state to another can be achieved with a minimal gadget consisting of two quarter waveplates. A constructive, geometric approach is presented, which provides a direct prescription for the fast axis setting of the waveplates to transform any completely polarized states of light to any other, including orthogonal ones. 
B. Radhakrishna
physics.optics