One of a number of cardboard models of light wavefronts made by Dr Norman Heckenberg as a way of understanding and then explaining the structure of 'optical vortices'.
These are 'singularities' or 'defects' in light wave fields where the intensity remains zero as the light waves swirl around. They occur naturally or can be induced artificially in several ways.
At the end of the 1980s Dr Heckenberg and Dr Carl-Otto Weiss and their students were studying such optical vortices produced by lasers in certain conditions.
Dr Heckenberg and his students subsequently developed holographic methods of embedding optical vortices in any laser beam. This embues the light with angular momentum and Heckenberg and Dr Halina Rubinsztein-Dunlop formed a team to find useful applications of this and other ways to trap and rotate microscopic particles. This work is still going on in 2015.
single singularity
