DYNAMIC APERTURE HOLOGRAPHY

• US 20150062675A1
• Filed: 03/21/2014
• Published: 03/05/2015
• Est. Priority Date: 01/23/2013
• Status: Active Grant

• Current Assignee: Akonia Holographics, LLC (Apple Inc.)
• Original Assignee: Akonia Holographics, LLC (Apple Inc.)
• Inventors: Ayres, Mark R., Anderson, Kenneth E., Askham, Fredric R., Sissom, Bradley J.
• Granted Patent: US 9,760,061 B2
• Time in Patent Office: Days
• US Class Current: 359/22
• CPC Class Codes: G03H 1/0248 Volume holograms
• CPC Class Codes: G03H 1/2645 Multiplexing processes, e.g. aperture, shift, or wavefront multiplexing
• CPC Class Codes: G03H 1/265 Angle multiplexing; Multichannel holograms G03H1/268 takes precedence
• CPC Class Codes: G03H 2001/267 Polarisation multiplexing
• CPC Class Codes: G11B 7/0065 Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
• CPC Class Codes: G11B 7/00772 on record carriers storing information in the form of optical interference patterns, e.g. holograms
• CPC Class Codes: G11B 7/1381 Non-lens elements for altering the properties of the beam, e.g. knife edges, slits, filters or stops G11B7/1353 - G11B7/1369 take precedence

Abstract

Methods and systems for performing dynamic aperture holography are described. Embodiments include a method of recording multiple holograms in a photosensitive recording medium, wherein multiple signal beam angular apertures used to record the multiple holograms differ from each other. The multiple signal beam angular apertures can facilitate using a larger range of reference beam angular apertures. The multiple holograms are typically multiplexed, and embodiments of dynamic aperture holography enable packing the multiplexed holograms more densely in the recording medium. Embodiments include dynamic aperture holography systems having monocular objective lens architecture.

Claims

1. A method of using dynamic aperture holography for recording multiple holograms, the method comprising:

projecting a first signal beam through an objective lens into a photosensitive recording medium at a first signal beam angular aperture;

projecting a first reference beam through the objective lens into the photosensitive recording medium at a first reference beam angular aperture, wherein the first reference beam and the first signal beam interfere with each other to form a first interference pattern, the first interference pattern being recorded as a first hologram in the photosensitive recording medium;

projecting a second signal beam through the objective lens into the photosensitive recording medium at a second signal beam angular aperture, wherein the second signal beam angular aperture differs from the first signal beam angular aperture in at least one of size, shape, and position; and

projecting a second reference beam through the objective lens into the photosensitive recording medium at a second reference beam angular aperture, wherein the second reference beam and the second signal beam interfere with each other to form a second interference pattern, the second interference pattern being recorded as a second hologram in the photosensitive recording medium.

2. The method of claim 1, wherein the first hologram at least partially overlaps the second hologram in the photosensitive recording medium.

3. The method of claim 2, wherein:

the first signal beam angular aperture is separated from the first reference beam angular aperture by a first separation angle; and

the second signal beam angular aperture is separated from the second reference beam angular aperture by a second separation angle.

4. The method of claim 3, wherein each of the first separation angle and the second separation angle are equal to or greater than a predetermined minimum separation angle.

5. The method of claim 4, wherein the first separation angle and the second separation angle differ by a separation angle dissimilarity equal to or greater than a predetermined minimum separation angle dissimilarity.

6. The method of claim 1, further comprising:

projecting a third signal beam through the objective lens into the photosensitive recording medium at a third signal beam angular aperture that differs from the first and second signal beam angular apertures in at least one of size, shape, and position;

projecting a third reference beam through the objective lens into the photosensitive recording medium at a third reference beam angular aperture, wherein the third reference beam and the third signal beam interfere with each other to form a third interference pattern, the third interference pattern being recorded as a third hologram in the photosensitive recording medium;

projecting a fourth signal beam through the objective lens into the photosensitive recording medium at a fourth signal beam angular aperture that differs from the first, second, and third signal beam angular apertures; and

projecting a fourth reference beam through the objective lens into the photosensitive recording medium at a fourth reference beam angular aperture, wherein the fourth reference beam and the fourth signal beam interfere with each other to form a fourth interference pattern, the fourth interference pattern being recorded as a fourth hologram in the photosensitive recording medium.

7. The method of claim 6, wherein each of the first, second, third, and fourth holograms at least partially overlaps all others of the first, second, third, and fourth holograms in the photosensitive recording medium.

8. The method of claim 7, wherein:

the first signal beam angular aperture is separated from the first reference beam angular aperture by a first separation angle;

the second signal beam angular aperture is separated from the second reference beam angular aperture by a second separation angle;

the third signal beam angular aperture is separated from the third reference beam angular aperture by a third separation angle; and

the fourth signal beam angular aperture is separated from the fourth reference beam angular aperture by a fourth separation angle.

9. The method of claim 8, wherein each of the first, second, third, and fourth separation angles are equal to or greater than a predetermined minimum separation angle.

10. The method of claim 9, wherein:

the first and third separation angles are substantially equal to each other; and

the second and fourth separation angles are substantially equal to each other.

11. The method of claim 10, wherein the first separation angle and the second separation angle differ from each other by a separation angle dissimilarity equal to or greater than a predetermined minimum separation angle dissimilarity.

12. The method of claim 11, wherein the predetermined minimum separation angle dissimilarity is at least 20 degrees.

13. The method of claim 11, wherein the predetermined minimum separation angle between 15 degrees and 100 degrees.

14. The method of claim 11, wherein the predetermined minimum separation angle is at least 20 degrees and the predetermined minimum separation angle dissimilarity is at least 30 degrees.

15. The method of claim 10, wherein:

the first signal beam angular aperture is separated from a reference beam angular aperture by less than the predetermined minimum separation angle; and

the reference beam angular aperture is selected from the group consisting of the second, third, and fourth reference beam angular apertures.

16. The method of claim 11, wherein the first signal beam angular aperture is separated from the third reference beam angular aperture by less than the predetermined minimum separation angle.

17. The method of claim 7, wherein the first signal beam angular aperture overlaps a reference beam angular aperture selected from the group consisting of the second, third, and fourth reference beam angular apertures.

18. The method of claim 11, wherein the first signal beam angular aperture overlaps the third reference beam angular aperture.

19. The method of claim 15, wherein;

the first, second, third, and fourth holograms are included in a set of multiple holograms;

the set of multiple holograms includes at least 150 holograms; and

each hologram in the set of multiple holograms at least partially overlaps every other hologram in the set of multiple holograms, in the photosensitive recording medium.

20. The method of claim 19, wherein the set of multiple holograms is angle multiplexed in one stack.

21. The method of claim 6, wherein:

the first hologram and the third hologram are used to store input data but not parity data;

the second hologram and the fourth hologram are used to store parity data but not input data;

the second signal beam angular aperture is smaller than the first signal beam angular aperture; and

the fourth signal beam angular aperture is smaller than the third signal beam angular aperture.

22. The method of claim 11, wherein:

the first hologram and the third hologram are used to store input data but not parity data;

the second hologram and the fourth hologram are used to store parity data but not input data;

the second signal beam angular aperture is smaller than the first signal beam angular aperture; and

the fourth signal beam angular aperture is smaller than the third signal beam angular aperture.

23. A method of using dynamic aperture holography for recording multiple holograms, the method comprising:

projecting a first signal beam into a photosensitive recording medium at a first signal beam angular aperture;

projecting a first reference beam into the photosensitive recording medium at a first reference beam angular aperture, wherein;

the first reference beam and the first signal beam interfere with each other to form a first interference pattern, the first interference pattern being recorded as a first hologram in the photosensitive recording medium; and

the first signal beam angular aperture is separated from the first reference beam angular aperture by a first separation angle;

projecting a second signal beam into the photosensitive recording medium at a second signal beam angular aperture, wherein the second signal beam angular aperture differs from the first signal beam angular aperture;

projecting a second reference beam into the photosensitive recording medium at a second reference beam angular aperture, wherein;

the second reference beam and the second signal beam interfere with each other to form a second interference pattern, the second interference pattern being recorded as a second hologram in the photosensitive recording medium; and

the second signal beam angular aperture is separated from the second reference beam angular aperture by a second separation angle;

projecting a third signal beam into the photosensitive recording medium at a third signal beam angular aperture that differs from the first and second signal beam angular apertures;

projecting a third reference beam into the photosensitive recording medium at a third reference beam angular aperture, wherein;

the third reference beam and the third signal beam interfere with each other to form a third interference pattern, the third interference pattern being recorded as a third hologram in the photosensitive recording medium; and

the third signal beam angular aperture is separated from the third reference beam angular aperture by a third separation angle;

projecting a fourth signal beam into the photosensitive recording medium at a fourth signal beam angular aperture that differs from the first, second, and third signal beam angular apertures;

projecting a fourth reference beam into the photosensitive recording medium at a fourth reference beam angular aperture, wherein;

the fourth reference beam and the fourth signal beam interfere with each other to form a fourth interference pattern, the fourth interference pattern being recorded as a fourth hologram in the photosensitive recording medium;

the fourth signal beam angular aperture is separated from the fourth reference beam angular aperture by a fourth separation angle; and

each of the first, second, third, and fourth separation angles are equal to or greater than a predetermined minimum separation angle.

24. The method of claim 23, wherein the predetermined minimum separation angle is at least 15 degrees.

25. The method of claim 24, wherein each of the first, second, third, and fourth holograms at least partially overlaps all others of the first, second, third, and fourth holograms in the photosensitive recording medium.

26. A method of using dynamic aperture holography for recording multiple holograms, the method comprising:

projecting a first signal beam through an objective lens into a photosensitive recording medium at a first signal beam angular aperture;

projecting a first reference beam through the objective lens into the photosensitive recording medium at a first reference beam angular aperture, wherein;

the first reference beam and the first signal beam interfere with each other to form a first interference pattern;

the first interference pattern is recorded as a first hologram in the photosensitive recording medium; and

the first signal beam angular aperture is separated from the first reference beam angular aperture by first separation angle;

projecting a second signal beam through the objective lens into the photosensitive recording medium at a second signal beam angular aperture, wherein the second signal beam angular aperture differs from the first signal beam angular aperture; and

projecting a second reference beam through the objective lens into the photosensitive recording medium at a second reference beam angular aperture that differs from the first reference beam angular aperture, wherein;

the second reference beam and the second signal beam interfere with each other to form a second interference pattern;

the second interference pattern is recorded as a second hologram in the photosensitive recording medium; and

the second signal beam is separated from the second reference beam by a second separation angle;

projecting a third signal beam through the objective lens into the photosensitive recording medium at a third signal beam angular aperture that differs from the first and second signal beam angular apertures;

projecting a third reference beam through the objective lens into the photosensitive recording medium at a third reference beam angular aperture, wherein;

the third reference beam and the third signal beam interfere with each other to form a third interference pattern;

the third interference pattern is recorded as a third hologram in the photosensitive recording medium; and

the third signal beam is separated from the third reference beam by a third separation angle;

projecting a fourth signal beam through the objective lens into the photosensitive recording medium at a fourth signal beam angular aperture that differs from the first, second, and third signal beam angular apertures; and

projecting a fourth reference beam through the objective lens into the photosensitive recording medium at a fourth reference beam angular aperture that differs from the first, second, and third reference beam angular apertures, wherein;

the fourth reference beam and the fourth signal beam interfere with each other to form a fourth interference pattern;

the fourth interference pattern is recorded as a fourth hologram in the photosensitive recording medium;

the fourth signal beam is separated from the fourth reference beam by a fourth separation angle;

each of the first, second, third, and fourth separation angles is greater than a predetermined minimum separation angle;

each of the first, second, third, and fourth holograms at least partially overlaps all others of the first, second, third, and fourth holograms in the photosensitive recording medium;

the first signal beam angular aperture is separated from a specified reference beam angular aperture by less than the predetermined minimum separation angle; and

the specified reference beam angular aperture is selected from the group consisting of the second, third, and fourth reference beam angular apertures.