Shaped reflective polarizer and optical system including same
A shaped reflective polarizer has different maximum sags in different directions and has an interior portion rotationally symmetric about a principle axis and a peripheral portion adjacent the interior portion and rotationally asymmetric about the principle axis. An optical system includes a partial reflector and an optical stack including an optical lens and the shaped reflective polarizer disposed on a curved major surface of the optical lens. The optical lens may have a contoured edge adapted to be placed adjacent an eye of a viewer and substantially conform to the viewer's face.
1 . A shaped reflective polarizer having a principle axis and a major axis along a projection onto a plane orthogonal to the principle axis of a line connecting two points farthest from each other on the shaped reflective polarizer, the reflective polarizer comprising a plurality of polymeric layers and configured to substantially transmit light having a first polarization state and substantially reflect light having an orthogonal second polarization state, the reflective polarizer stretched and shaped so as to have a first maximum sag in a first direction and a different second maximum sag in an orthogonal second direction, the shaped reflective polarizer having an interior portion rotationally symmetric about the principle axis and a peripheral portion adjacent the interior portion and rotationally asymmetric about the principle axis.
2 . The shaped reflective polarizer of claim 1 , wherein the first polarization state is along one of the first and second directions and the second polarization state is along the other of the first and second directions.
3 . The shaped reflective polarizer of claim 1 , wherein the first and second maximum sags are at respective first and second radii from the principle axis in the respective first and second directions, a first ratio of the first maximum sag to the first radius being at least 1.05 times a second ratio of the second maximum sag to the second radius, the second ratio being at least 0.1.
4 . An optical stack comprising:
an optical lens having a curved major surface; and
the shaped reflective polarizer of claim 1 disposed on the curved major surface, wherein the interior and peripheral portions of the shaped reflective polarizer are disposed on, and substantially conform to, respective interior and peripheral portions of the curved major surface.
5 . An optical system comprising:
the optical stack of claim 4 ; and
a partial reflector having an average optical reflectance of at least 30% for at least one desired wavelength,
wherein the principle axis is along an optical axis of the optical system, such that a light ray propagating along the optical axis passes through the optical stack and the partial reflector without being substantially refracted.
6 . The optical system of claim 5 being adapted for displaying an image to a viewer, wherein the optical lens comprises a contoured edge adapted to be placed adjacent an eye of the viewer and substantially conform to the viewer's face.
7 . The optical system of claim 5 further comprising a display emitting an image for viewing by an eye of a viewer, wherein a first image ray emitted by the display propagating along the optical axis passes through the optical stack and the partial reflector without being substantially refracted and passes through a pupil of the eye of the viewer, and
at least one second image ray emitted by the display and making a first oblique angle with the optical axis, passes through the optical stack and the partial reflector, and passes through the pupil of the eye of the viewer, such that a straight line coincident with the at least one second image ray intersects a facial feature of the viewer at an intersection point, the display disposed between the intersection point and the eye of the viewer.