Optical arrangement and an autostereoscopic display device incorporating the same
An optical arrangement having at least a lens mode in which the optical arrangement is a lens arrangement having an array ( 9 ) of lenticular lenses ( 11 ) each of which has a particular lens surface shape such that, when tracing rays through a lenticular lens after they have entered one side of the lenticular lens, there exists at least one ray that hits the lenticular lens surface perpendicularly. This arrangement gives reduced banding and loss of intensity at steep angles when used in an autostereoscopic display.
1. An optical arrangement having at least a lens mode in which it is a lens arrangement comprising an array of lenticular lenses which comprise a first layer and a second layer having an interface between each other defining a surface of the array of lenticular lenses, the first layer having a first refractive index at the 587.5618 nm D3 helium line and the second layer having a second refractive index at the 587.5618 nm D3 helium line which is larger than the first refractive index, wherein the lens surface of each lenticular lens defines a convex lenticular lens shape for rays entering the lenticular lens from the second layer, and has a particular lens surface shape with sufficient curvature such that, when tracing rays through a lenticular lens after they have entered one side of the lenticular lens opposite the side with the lens surface shape, there exists at least one ray, for every incoming angle to said one side, that hits the lenticular lens surface perpendicularly, and wherein the difference between the second and the first refractive indices is in the range 0.05-0.15.
2. The optical arrangement as claimed in claim 1 , wherein the optical arrangement is for positioning between a display device and a viewer, wherein the first layer is positioned at the side of the viewer.
3. The optical arrangement as claimed in claim 1 , wherein the difference between the second and the first refractive indices is in the range 0.09-0.12.
4. The optical arrangement as claimed in claim 1 , wherein the second refractive index is in the range 1.4-1.65.
5. The optical arrangement as claimed in claim 1 , wherein the first refractive index is in the range 1.3-1.5.
6. The optical arrangement as claimed in claim 1 , wherein the first layer and the second layer are optically isotropic.
7. The lens arrangement as claimed in claim 1 , wherein the first and second layers have substantially the same Abbe number.
8. The lens arrangement as claimed in claim 1 , having an area wherein the interface between the first layer and the second layer is substantially flat.
9. An autostereoscopic display device comprising:
an image providing means and an optical arrangement according to claim 1 , wherein the optical arrangement is positioned in front of the image providing means.
10. The autostereoscopic display device as claimed in claim 9 , wherein the image forming means is an electronic display panel.
11. The autostereoscopic device as claimed in claim 9 or 10 , wherein the optical arrangement is positioned such that the second layer is closer to the image providing means than the first layer.
12. A method of displaying an autostereoscopic image, comprising providing an image comprising multiple views and projecting the image through an optical arrangement as claimed in claim 1 .