Devices And Methods For A Micro-Fresnel Zone Plate Optical Device

• US 20100118683A1
• Filed: 06/24/2009
• Published: 05/13/2010
• Est. Priority Date: 08/15/2008
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: Administrator of The National Aeronautics, Space Administration
• Inventors: Park, Yeonjoon, Choi, Sang H., King, Glen C., Elliott, James R.
• Granted Patent: US 8,018,815 B2
• Time in Patent Office: Days
• US Class Current: 369/109.10
• CPC Class Codes: G11B 2007/0006 adapted for scanning different types of carrier, e.g. CD & DVD
• CPC Class Codes: G11B 2007/13722 Fresnel lenses
• CPC Class Codes: G11B 7/1353 Diffractive elements, e.g. holograms or gratings diffraction gratings per se G02B5/18; holograms per se G02B5/32; grating systems G02B27/44
• CPC Class Codes: G11B 7/1374 Objective lenses optical objectives per se G02B9/00

Abstract

An embodiment generally relates to an optical device suitable for use with an optical medium for the storage and retrieval of data. The optical device includes an illumination means for providing a beam of optical radiation of wavelength λ and an optical path that the beam of optical radiation follows. The optical device also includes a diffractive optical element defined by a plurality of annular sections. The plurality of annular sections having a first material alternately disposed with a plurality of annular sections comprising a second material. The diffractive optical element generates a plurality of focal points and densely accumulated ray points with phase contrast phenomena and the optical medium is positioned at a selected focal point or ray point of the diffractive optical element.

Claims

1. 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 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 a 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; and

an optical medium is positioned at one of a selected diffractive focal point and a selected densely accumulated ray point which is surrounded by one or multiple of destructive interference ring patterns of the diffractive optical element.

2. The optical device of claim 1, wherein the plurality of annular sections comprising a first material is one of transparent with first refractive index or opaque.

3. The optical device of claim 2, wherein the plurality of annular sections comprising a second material is the other of transparent with second refractive index or opaque.

4. The optical device of claim 1, wherein a focal length of the diffractive optical element is longer than wavelength of the laser and shorter than ten centimeters.

5. The optical device of claim 1, wherein the diffractive optical element is implemented with photonic DART technology, wherein the diffractive optical element generates a bright ray point that is sharpened by surrounding one or multiples of concentric destructive interference patterns.

6. The optical device of claim 5, wherein the plurality of diffractive focal points comprises integer constructive interference focal points, integer destructive interference focal points and a non-integer densely accumulated ray point which is sharpened by surrounding concentric destructive interference ring patterns.

7. The optical device of claim 6, wherein the selected focal point is a non-integer densely accumulated ray point that is sharpened by surrounding concentric destructive interference ring patterns.

8. The optical device of claim 1, further comprising an electro-optic layer that changes the refractive index when an electric field is applied to modulate the respective distances of the plurality of diffractive focal points.

9. The optical device of claim 8, wherein the electro-optic layer is configured to be implemented with one of an electro-optic crystal, an electro-optic polymer, and a liquid crystal.

10. The optical device of claim 1, wherein the storage medium is one of dye-based medium, a phase-change medium, and a photo-luminescence medium.