Embossed volume holograms: the Aztec structure

Embossed holograms are surface-relief structures that typically result from recordings made interferometrically by the off-axis technique, where the fringe maxima lie on planes predominantly perpendicular to the recording surface and with an intensity variation that is sinusoidal. A new type of holographic recording called Aztec is discussed that combines features of off-axis and volume recording schemes, with the result being a phase-quantized, or terraced surface relief pattern. The groove profile, instead of being sinusoidal, resembles a stepped pyramid. This structure can be replicated by metal mastering and molding into plastic in the same manner as conventional embossed holograms, but the diffraction characteristics are typical of volume holograms. Additional features include color control and information content, which is less for the single-layered, but stepped, Aztec structure than for the usual multilayered volume diffractive element