Experiments with holograms have led to a thin-film flat-plate lens that has a periodic (layered) structure and that is capable of a resolution of 100 nm or finer. The flat lens provides excellent image-forming characteristics by the incidence of light having a wavelength slightly shorter than the wavelength corresponding to the frequency period of the thin film. The structure can exhibit a negative refractive index at high angles of incidence. This lens technology exhibits uniform performance in image formation all over the lens surface. The thin film of the periodic structure is formed by alternate laminations (and pluralities of laminations) of two materials having different refractive indices.
The technology also provides for optical recording in high density when the lens is inserted into the optical path leading to the recording layer from a light source. Applications include high-density optical digital data recording and retrieval, and other applications demanding fine resolution or negative refractive index.
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