Compact optical system with improved contrast uniformity
View Patent ↗An optical system for a head-worn computer may include a light source positioned within the head-worn computer and adapted to project non-polarized illuminating light towards a partially reflective partially transmissive surface such that the illuminating light reflects through a field lens and towards a reflective display and a polarizing film adjacent to a surface of the reflective display that polarizes the illuminating light after it passes through the field lens. The illuminating light reflects off a surface of the reflective display, forming image light which is then analyzed by the polarizing film prior to being transmitted through the field lens and then through the partially reflective partially transmissive surface to a non-polarizing lower display optical system adapted to present the image light to an eye of a user wearing the head-worn computer.
1. An optical system for a head-worn computer, comprising:
a light source positioned within the head-worn computer and adapted to project non-polarized illuminating light towards a partially reflective partially transmissive surface such that the illuminating light reflects through a field lens and towards a reflective display; and
a polarizing film adjacent to a surface of the reflective display that polarizes the illuminating light after it passes through the field lens,
wherein the illuminating light reflects off a surface of the reflective display, forming image light which is then analyzed by the polarizing film prior to being transmitted through the field lens and then through the partially reflective partially transmissive surface to a non-polarizing lower display optical system adapted to present the image light to an eye of a user wearing the head-worn computer.
2. The optical system of claim 1 , wherein the field lens has more than 30 nm of birefringence.
3. The optical system of claim 1 , wherein the polarizing film is an absorptive polarizer.
4. The optical system of claim 1 , wherein the polarizing film is a circular polarizer.
5. The optical system of claim 4 , wherein the quarter wave film of the circular polarizer faces the reflective display.
6. The optical system of claim 1 , wherein the non-polarizing lower display system also provides a see-through view of the surrounding environment.
7. The optical system of claim 1 , wherein the reflective display is an LCOS or FLCOS.
8. The optical system of claim 1 , wherein the reflective display is an interferometric modulator display.
9. The optical system of claim 1 , further comprising a light trap positioned adjacent to a wall of a housing opposite the light source to trap stray light that is not reflected by the partially reflective partially transmissive surface.
10. The optical system of claim 9 , wherein the light trap includes flat black paint.
11. The optical system of claim 9 , wherein the light trap includes a textured structure.
12. The optical system of claim 1 , wherein the partially reflective partially transmissive surface is a segmented surface with at least one flat segment.