Micro-Fresnel zone plate optical devices using densely accumulated ray points

An optical device suitable for use with an optical medium for the storage and retrieval of data, the optical device comprising:

• an illumination means for providing a beam of optical radiation of wavelength λ;
• an optical path that the beam of optical radiation follows;
• and
• a single planar diffractive optical element configured to comprise a plurality of annular sections comprising a first material alternately disposed with a plurality of annular sections comprising a second material or a different thickness of the first material, wherein the diffractive optical element is configured to generate a plurality of diffractive focal points and a plurality of densely accumulated ray points on an optical axis away from the diffractive optical element;
• and
• an optical medium positioned at a selected densely accumulated ray point which is surrounded by one or multiple of zero-light-intensity destructive interference ring patterns that are located near the optical axis away from the diffractive optical element.