Search

We exploit the birefringence of cellophane to convert a linearly polarised Gaussian beam into either a radially or azimuthally polarised beam. For that, we fabricated a low-cost polarisation mask consisting of four segments of cellophane. The fast axis of each segment is oriented appropriately in order to rotate the polarisation of the incident linearly polarised beam as desired. To ensure the correct operation of the polarisation mask, we tested the polarisation state of the generated beam by measuring the spatial distribution of the Stokes parameters. Such a device is very cost efficient and allows for the generation of cylindrical vector beams of high quality.

The application of the Poincare sphere to the analysis of the effect of retarders is outlined and is then applied to the problem of making a half-wave plate from three plates which each have a retardance delta . It is shown that an arrangement having two plates with their fast axes parallel and between them a third plate with its fast axis at an angle gamma behaves as a half-wave plate if cos gamma =1/2sin( delta /2).