Patent ID: 7466487

Claim:
A light diffraction method using a diffraction grating, wherein: the diffraction grating comprises: a first layer containing two or more first light scatterers, two or more of which being periodically arrayed along a first direction and either a) two or more of which being arrayed along a second direction or b) extending along the second direction; and a second layer containing two or more second light scatterers respectively corresponding to the two or more first light scatterers, the two or more second light scatterers being disposed at positions shifted from the two or more first light scatterers by a predetermined distance along a predetermined direction in a plane that is other than a plane containing the first direction and the second direction; the method comprising: making light incident on the diffraction grating so that: in a case of a), the light is incident along a plane containing two or more trajectories selected from trajectories formed by the shifting of the two or more first light scatterers in the predetermined direction; and in both cases of a) and b), specular resonance occurs in two or more light scattering units, each comprising one light scatterer selected from the two or more first light scatterers and one of the second light scatterers corresponding to the selected one of the first light scatterers, whereby a fraction of diffracted light that is diffracted by the first layer and the second layer is enhanced selectively by the specular resonance in the two or more light scattering units.