LCOS illumination via LOE
A system for uniform optical illumination of an image light provider in a smaller (compact) configuration than conventional implementations includes a lightguide having: a first external surface and a second external surface mutually parallel, and a first sequence of facets, at least a portion of which are: a plurality of parallel, partially reflecting, and polarization selective surfaces, at an oblique angle relative to the first and second external surfaces, and between the first and second external surfaces, and a front-lit reflective polarization rotating image modulator: deployed to spatially modulate light coupled-out from the first external surface, outputting reflected light corresponding to an image, and deployed such that the reflected light traverses the lightguide from the first external surface via the first sequence of facets to the second external surface.
1. An optical system comprising:
(a) an illumination source configured to output light from an effective source aperture;
(b) a front-lit reflective spatial light modulator (SLM) deployed to modulate light incident on said SLM and to output modulated reflected light corresponding to an image, said SLM being larger than said effective source aperture in two dimensions;
(c) a lightguide arrangement including a first lightguide region and a second lightguide region, said first lightguide region receiving light from said illumination source and guiding the light while the light expands in at least one dimension to propagate within said second lightguide region, said second lightguide region having a pair of mutually-parallel external surfaces for guiding the light by internal reflection, one of said external surfaces being in facing relation to said SLM;
(e) a coupling-out arrangement associated with said second lightguide region and configured for progressively coupling out the light propagating within said second lightguide region towards said SLM; and
(d) a polarizer deployed to selectively transmit image illumination reflected from said SLM, said image illumination passing through said pair of mutually-parallel external surfaces.
2. The optical system of claim 1 , further comprising a polarization management component deployed for modifying a polarization state of the light prior to entry into said second lightguide region.
3. The optical system of claim 1 , wherein said coupling-out arrangement comprises a sequence of selectively reflecting surfaces associated with said second lightguide region and oriented obliquely to said pair of external surfaces.
4. The optical system of claim 3 , wherein each of said selectively reflecting surfaces reflect a portion of a first polarized light and transmit a remaining portion of said first polarized light, and transmit a second polarized light.
5. The optical system of claim 3 , wherein each of said selectively reflecting surfaces is partially reflecting within a first angular range and is non-reflecting within a second angular range.
6. The optical system of claim 3 , wherein each of said selectively reflecting surfaces is partially reflecting with a maximum reflectivity within an angular range, said selectively reflecting surfaces their respective maximum reflectivity in differing angular ranges.
7. The optical system of claim 1 , wherein said first lightguide region has a pair of mutually-parallel major external surfaces, and a sequence of selectively reflecting surfaces associated with said first lightguide region, said sequence of selectively reflecting surfaces deflecting the light towards the second lightguide region.
8. The optical system of claim 1 , wherein said first lightguide region has a pair of surfaces that diverge towards said second lightguide region.
9. The optical system of claim 1 , wherein said first lightguide region has a first pair of mutually parallel external surfaces and a second pair of mutually parallel external surfaces, said second pair of external surfaces being perpendicular to said first pair of external surfaces, for guiding the light from said illumination source, and a coupling-out arrangement for progressively coupling out the light towards the second lightguide region.
10. The optical system of claim 1 , wherein said first lightguide region and said second lightguide region are integrated into a single contiguous lightguide.