Arguably amongst the most startling properties of metamaterials are some that are fundamentally wave-optical, and therefore not reproduced in METATOYs. These include amplification of evanescent waves, which can, in principle, lead to perfect lenses ("superlenses") and magnifying superlenses ("hyperlenses"); reversal of the phase velocity; reversal of the Doppler shift. However, because they are not bound by wave-optical constraints on light-ray fields, it can be argued that METATOYs can perform light-ray-direction changes that metamaterials could not, unless a METATOY was effectively built out of metamaterials. See also Fresnel lens Zone plate References External links Didactic article on METATOYs Geometrical optics Optical devices Optical materials Imaging