Optical vortex diffractive optical element-scattering application

An optical vortex diffractive element was constructed by etching a plate of glass in a spiral staircase shape, such that the thickness of the glass increased in the azimuthal direction of the glass plate. The phase mask was then used to detect the light forward scattered through a colloidal solution. In the center of the optical vortex, the bright coherent laser beam was darkened owing to destructive interference allowing the detection of the incoherent scattered light. (c) 1999 Optical Society of America.