Reference beam absorbers-blockers
View Patent ↗In accordance with teachings of the present invention, a device accomplishes the task of reducing or preventing reflections of the reference beam off a diffuser from striking the holographic recording material. First, the device absorbs a large percentage of the reference beam power so that portion of the reference beam never reaches the diffuser. Second, the device blocks the small amount of reference beam that is incident on the diffuser and reflects back toward the film. Thus, the proposed device operates as an absorber-blocker (AB) for the reference beam.
1. A system for recording a hologram in a holographic recording material, the holographic recording material having at least a portion including a first surface and a second surface, the system comprising:
a diffuser disposed adjacent to the second surface whereby an object beam directed at the second surface can pass through the diffuser prior to contacting the holographic recording material; and
an absorber-blocker disposed between the second surface and the diffuser to prevent at least a portion of a reference beam directed at the first surface from impinging on the diffuser, the absorber-blocker including:
a plurality of absorber-blocker material elements wherein at least one of the plurality of absorber-blocker material elements is a thin layer of material having a first absorber-blocker surface and a second absorber-blocker surface, and wherein the first absorber-blocker surface and the second absorber-blocker surface are in respective planes that are substantially parallel to a plane defined by the diffuser.
2. The system of claim 1 , wherein
the absorber-blocker is operable to allow approximately all light from the object bean to pass therethrough and to absorb approximately all light from the reference beam striking the absorber-blocker.
3. The system of claim 1 , wherein the diffuser is an anisotropic diffuser.
4. The system of claim 1 , wherein the diffuser further comprises a lenticular array.
5. The system of claim 1 , wherein the absorber-blocker is formed on a surface of the diffuser.
6. The system of claim 1 , wherein the absorber-blocker is formed on a substrate separate from the diffuser.
7. The system of claim 6 , wherein the substrate is one of a plastic substrate and a glass substrate.
8. The system of claim 1 , wherein at least two of the plurality of absorber-blocker material elements are arranged parallel to each other.
9. The system of claim 1 , wherein the thin layer of material is absorptive at wavelengths being used for holographic recording.
10. The system of claim 9 , wherein the thin layer of material is at least one of an absorptive ink, an absorptive paint, a plastic, and an exposed photoactive material.
11. The system of claim 9 , wherein the absorber-blocker is fabricated such that the plurality of absorber-blocker material elements exists only where the object beam will not be incident on the absorber-blocker and will not exist where the object beam is incident upon the absorber-blocker.
12. The system of claim 1 , wherein the absorber-blocker is located in a plane of minimum object beam area.
13. The system of claim 1 , wherein multiple reference beams are directed at the first surface and multiple object beams are directed at the second surface for recording substantially full color holograms.
14. The system of claim 1 , wherein multiple reference beams are directed at the first surface and multiple object beams are directed at the second surface for recording horizontal parallax only holograms.
15. The system of claim 1 , wherein multiple reference beams are directed at the first surface and multiple object beams are directed at the second surface for recording full parallax holograms.
16. The system of claim 1 further comprising:
a laser operable to provide a coherent light beam;
a beam splitter disposed to split the coherent light beam into the reference beam and the object beam; and
a spatial light modulator disposed between the holographic recording material and the beam splitter such that the object beam passes through the spatial light modulator.
17. The system of claim 16 wherein the spatial light modulator is a computer controlled liquid crystal display.
18. The system of claim 17 further comprising:
a computer system coupled to the liquid crystal display and operable to provide image data to the liquid crystal display.