Figure 3

3D view, with z-axis reversed, of two different "eight"
symbols.
(a) Shows the eight written in an anticlockwise way. In
contrast, (b) shows the eight written in a clockwise way (photo and text: Spagnolo et al. 2004 J. Opt. A. 6 869).

3D view, with z-axis reversed, of two different "eight"
symbols.
(a) Shows the eight written in an anticlockwise way. In
contrast, (b) shows the eight written in a clockwise way (photo and text: Spagnolo et al. 2004 J. Opt. A. 6 869).