High efficiency viewing screen
A low-scatter polarization-preserving multilayer viewing screen. A substrate D, preferably a volume diffuser, for increasing the divergence of information-coded-light while preserving its polarization sense A as it passes therethrough has a discrimination of at least 2:1 within a viewing zone. An absorbing polarizer on one or both sides of D and aligned to pass polarization state A. In one embodiment, there is provided a polarization-state phase-shift layer for modifying the polarization state of forward-scatter and/or back-scatter that total internally reflects within the viewing screen into the state opposite of A. The phase-shift layer being located at any position between the polarizer and an outermost surface of the viewing screen through which said information-coded light passes.
1. A viewing screen for increasing the divergence of information-coded-light incident on its input surface, exiting its output surface into a viewing zone, having high ambient light rejection and low retroreflectance comprising:
a diffuser, comprised of a material substantially devoid of regular geometric objects (i) distributed therein having an average size that is greater than a wavelength of said information-coded-light and (ii) having geometrical concavity open to at least a portion of said viewing zone,
wherein said diffuser exhibits a polarization-preserving discrimination ratio of at least 2:1 throughout said viewing zone, said screen further comprising (i) at least one absorbing means and (ii) a substantially non-diffusing antireflection means on its output surface.
2. The viewing screen of claim 1 , wherein said at least one ambient light absorbing means is optically coupled to said diffuser.
3. The viewing screen of claim 2 , wherein the ambient-light absorbing means comprises at least one of a polarizer, a wavelength-selective absorber, a neutral density absorber, and a time-sequenced absorbing shutter.
4. The viewing screens of claim 2 , wherein the ambient-light absorbing means comprises multiple polarizer layers of the linear/circular polarization type, wherein each polarizer layer has its polarization axis aligned to the other.
5. The viewing screen of claim 2 , wherein the ambient-light absorbing means comprises a thin film deposition directly on said diffuser.
6. The viewing screen of claim 1 , wherein said diffuser is a surface diffuser with an absorptive means in contact with its topographic features.
7. The viewing screen of claim 6 , wherein said absorptive means is a deposition/coating on the top of the topographic features, a dye or impregnation within a depth starting at the topographic features, contained within the bulk of said diffuser, or some combination thereof.
8. The viewing screen of claim 1 , wherein said diffuser is a volume diffuser.
9. The viewing screen of claim 1 , in combination with at least one of a projection and a direct-view system.
10. The viewing screen of claim 9 , wherein the system comprises a polarization-based 3D imaging application.
11. The viewing screen of claim 1 , further comprising a specular reflector.
12. The viewing screen of claim 1 , further comprising a fresnel-reflection reduction means.
13. The viewing screen of claim 12 , wherein the fresnel-reflection reduction means comprises at least one of index-matching fluid, index-matching gel and index-matching adhesive.
14. The viewing screen of claim 12 , wherein the fresnel-reflection reduction means comprises a Motheye or an equivalent nanostructure.
15. The viewing screen of claim 1 , wherein the viewing screen has at least one of the following configurations: A/D/P/A, A/P/D/P, P/D/P/A, A/P/D/P/A, wherein A corresponds to an antireflective coating, D corresponds to said diffuser, and P corresponds to said ambient-light absorbing means.
16. The viewing screen of claim 15 , wherein an interface between P/D layers and/or D/P layers comprises a fresnel reflection reduction means.
17. The viewing screen of claim 16 , wherein the interface between the D/P layers comprises an index-matching adhesive.
18. An imaging system comprising the viewing screen of claim 1 in combination with a source of said information coded light, wherein the speckle contrast is less than 6.
19. A low-scatter polarization-preserving multilayer viewing screen for increasing the divergence of information coded light, comprising:
a substrate for increasing the divergence of information-coded-light, while preserving its polarization state A, as it passes therethrough with a discrimination of at least 2:1 within a viewing zone;
an absorbing polarizer on one or both sides of said substrate and aligned to pass polarization state A; and
a polarization-state phase-shift layer for modifying the polarization state of forward-scatter and/or back-scatter that total internally reflects within said viewing screen into the state opposite of state A, said phase-shift layer being located at any position between the polarizer and an outermost surface of the viewing screen through which said information-coded light passes.
20. The viewing screen of claim 19 , farther comprising fresnel-reflection reduction means in contact with the surface of one or more layers through which said information-coded light passes.
21. The viewing screen of claim 19 , further comprising at least an anti-reflective coating.
22. The viewing screen of claim 19 , wherein the antireflective coating comprises a thin film deposition or nanostructure applied directly to the ambient-light absorbing means or on a transparent substrate that is thereafter applied to the ambient-light absorbing means.
23. The viewing screen of claim 19 , wherein said diffuser is a volume diffuser.
24. The viewing screen of claim 19 , in combination with at least one of a projection and a direct-view system.
25. The viewing screen of claim 24 , wherein the system comprises a polarization-based 3D imaging application.
26. An imaging system comprising the viewing screen of claim 19 in combination with a source of said information coded light, wherein the speckle contrast is less than 6.