The Tartan Geometry of Light

As a research group based in Scotland we are naturally proud and excited every time light reveals its tartan nature to us.

Below are a few of the generalised optical tartans we discovered.

Video-feedback tartan

A tartan resulting from video feedback with a pixellated monitor

This tartan was observed at the same time as the other video-feedback patterns shown in Leach et al., Fractals in pixellated video feedback, Contemp. Phys. 44, 137 (2003), https://doi.org/10.1080/0010751021000029598.

Tartan with a dislocation

A pattern containing a discontinuity and vaguely resembling a tartan 

Colour representation of a phase hologram (shown in Fig. 4(d) in Gibson et al., Free-space information transfer using light beams carrying orbital angular momentum, Opt. Express  12, 5448 (2004), https://doi.org/10.1364/OPEX.12.005448).  It clearly has a discontinuity at its centre, but as far as generalised tartans go this one is very generalised.

Diffraction tartan

Far-field diffraction pattern behind a ray-rotation sheet, resembles a detail from a tartan

Far-field diffraction pattern behind a 90° ray-rotating sheet (Hamilton et al., Local light-ray rotation, J. Opt. A: Pure Appl. Opt. 11, 085705 (2009), http://dx.doi.org/10.1088/1464-4258/11/8/085705).  It looks like part of a tartan, complete with stitches.  Weaved by diffraction.

The official tartan of the University of Glasgow

... can be found at https://www.tartanregister.gov.uk/tartanDetails?ref=1360.  We also didn't know that the University of Glasgow had one.