Pixellated imaging: from generalised lenses to cloaks

I will talk about the possibilities pixellated ray optics offers for geometrical imaging. These possibilities include generalised lenses and large-scale, but pixellated, transformation-optics devices. We believe that the latter can be realised on length scales so much larger than conventional transformation-optics devices that they will lead to completely new applications.

But what on earth is pixellated ray optics? Much of standard ray optics is informed by theorems derived for globally continuous wave fronts. This limits the properties of the resulting light-ray fields, which are wave-front normals. Our group has pioneered a systematic exploration of an extension of ray optics, pixellated ray optics, which specifically allows wave fronts to be piecewise continuous and which is therefore not limited by theorems derived for globally continuous wave fronts. The wave-front pieces result from transmission through pixellated optical devices. If the wave-front pieces are small (but not so small that diffraction dominates - note that pixellated ray optics is, in general, different from diffractive optics), this pixellation can be as unnoticeable as in a computer monitor. The vision of our work is that, by replacing globally continuous wave fronts with piecewise continuous wave fronts, the possibilities offered by optics, specifically ray optics, can be significantly extended.