Propogation of Half a
Gaussian beam through a Fork Diffraction Grating
Optical vortices have a built in handedness,
the direction of twist in the spiraling phase pattern of the
propogating beam, directly related to the positive or negative order
of the resulting diffraction pattern after a CGH diffraction grating. Arlt, insert referebce, showed that the handedness can be found by directly by obstructing half of a beam from one of the orders with a knife edge and observing the radial shift. We attempted to obstruct the beam before it entered the grating, close enough that the half gauusian beam shape would be maintained as it entered the CGH.