Light modulator for optical image projection
View Patent ↗A spatial light modulator comprising an array-type liquid crystal panel, a polarization beam splitter, an oblique wave plate and a converging lens. The polarization beam splitter is orientated to direct a source light towards a reflective planar surface of the array-type liquid crystal panel. The oblique wave plate and converging lens are located between the polarization beam splitter and the array-type liquid crystal panel. The converging lens is configured to direct light from the reflective planar surface onto a facing surface of the polarization beam splitter.
1. A method of projecting an image, comprising:
directing a source light beam through a polarization beam splitter towards a reflective planar surface of a array-type liquid crystal panel, wherein said polarization beam splitter has a planar surface facing said reflective planar surface;
reflecting said source light off of first and second sets of liquid crystal pixels of said array-type liquid crystal panel, said first and second sets of liquid crystal pixels causing reflected light to be in different polarization states;
passing said reflected light through a converging lens, wherein said converging lens is located between said polarization beam splitter and said array-type liquid crystal panel, and, said converging lens directs said reflected light from said planar reflective surface to a facing surface of said polarization beam splitter; and
passing said reflected light through an oblique wave plate.
2. The method of claim 1 , further includes passing said reflected light from said first set of pixels straight through said polarization beam splitter to projection optics.
3. The method of claim 1 , further includes reflecting said reflected light from said first set pixels through said polarization beam splitter to projection optics.
4. The method of claim 1 , further including directing said source light beam generated from a light source to said polarization beam splitter.
5. The method of claim 1 , wherein said oblique wave plate is located between said polarization beam splitter and said array-type liquid crystal panel.
6. The method of claim 1 , wherein said oblique wave plate is located between said polarization beam splitter and said converging lens.
7. The method of claim 1 , wherein said oblique wave plate is located between said converging lens and said array-type liquid crystal panel.
8. The method of claim 1 , wherein the converging lens is closer to the array-type liquid crystal panel than any other lens of the modulator.
9. The method of claim 1 , wherein passing said reflected light through said oblique wave plate compensates polarization changes due to reflection from non-activated pixels of the array type liquid crystal panel.
10. The method of claim 1 , further including rotating a planar surface of said oblique wave plate with respect to a normal axis to said oblique wave plate, to define an angle between an optical axis of said oblique wave plate and said normal axis, wherein the angle is in a range from 3 to 4 degrees with respect to a horizontal plane of said modulator.
11. The method of claim 1 , wherein said oblique wave plate is composed of a birefringent material having an optical axis that is neither parallel nor perpendicular relative to outer surfaces of the oblique wave plate.