Planar lenses for integrated optics
Planar lenses for integrated optics applications, in particular for use in optical touch screen sensors are disclosed. The disclosed planar lenses include a slab waveguide and an optical waveguide, preferably formed in unitary fashion, wherein the slab waveguide has a curved end face to focus light into or out of the optical waveguide, and wherein at least one additional lens is included within the slab waveguide. In one aspect of this disclosure, the additional lens is a diverging lens. In a second aspect the additional lens is a converging lens. The additional lens may match the acceptance angle of the optical waveguide to the curved end face of the slab waveguide. Alternatively, it may improve the tolerance of the planar lens to design or assembly errors and/or temperature variations. Preferably, the planar lenses are composed of a photo-patternable polymer, and the additional lenses are composed of air.
1. An optical element comprising a planar lens and an optical waveguide, said planar lens comprising a slab waveguide formed from a first medium of first refractive index, with said optical waveguide connected to a first end of said slab waveguide and a curved surface forming a second end of said slab waveguide, said slab waveguide containing a diverging lens formed from a second medium of second refractive index, different from said first refractive index, wherein said curved surface forms a converging lens such that as light passes from said optical waveguide through said slab waveguide its divergence is enhanced by said diverging lens before said light is converged by said curved surface so as to form a substantially collimated beam upon exiting said slab waveguide.
2. An optical element according to claim 1 , wherein said planar lens and said optical waveguide are continuous and formed from the same material.
3. An optical element according to claim 1 , wherein said first medium is an optically transparent glass or polymer material.
4. An optical element according to claim 1 , wherein said second refractive index is lower than said first refractive index.
5. An optical element according to claim 4 , wherein said second medium is air.
6. An optical element according to claim 4 , wherein said diverging lens is bi-convex, plano-convex or meniscus convex in shape.
7. An optical touch screen sensor including at least one transmit optical element or at least one receive optical element, wherein:
said transmit optical element or said receive optical element comprises a planar lens and an optical waveguide, said planar lens comprising a slab waveguide formed from a first medium of first refractive index, with said optical waveguide connected to a first end of said slab waveguide and a curved surface forming a second end of said slab waveguide, wherein said slab waveguide contains a diverging lens formed from a second medium of second refractive index, different from said first refractive index, wherein said curved surface forms a converging lens such that as light passes from said optical waveguide through said slab waveguide its divergence is enhanced by said diverging lens before said light is converged by said curved surface so as to form a substantially collimated beam upon exiting said slab waveguide.
8. An optical touch screen sensor according to claim 7 , wherein said planar lens and said optical waveguide are continuous and formed from the same material.
9. An optical touch screen sensor according to claim 7 , wherein said first medium is an optically transparent glass or polymer material.
10. An optical touch screen sensor according to claim 7 , wherein said second refractive index is lower than said first refractive index.
11. An optical touch screen sensor according to claim 10 , wherein said second medium is air.
12. An optical touch screen sensor according to claim 10 , wherein said diverging lens is bi-convex, plano-convex or meniscus convex in shape.