Fig. 3G shows that when footprints 24 are moved away from the origin in angular space the maximum angle of scattering that the diffuser can provide without spill over of light outside of circle 23 is reduced. In Fig. 3G effective footprints 25A and 25B still fill much of the angular space within circle 23 but less completely than in Fig. 3F. The area of overlap 26 between effective footprints 25A and 25B is also reduced relative to Fig. 3F.