Injection-molded thick lens

1. A thick lens for use with a light source, the lens being made by injection molding in a mold through the injection of a molten plastic material in at least three injection shots using a multistep process, the lens including:

a first outer lens part having opposite first and second surfaces, the first surface of the first outer lens part defining a first optical active surface of the lens that refracts incoming light beams from the light source;

a second outer lens part having opposite first and second surfaces, the first surface of the second outer lens part defining a second optical active surface of the lens that refracts the incoming light beams from the light source; and

a lens core part forming an interior of the lens and that is embedded between the first outer lens part and the second outer lens part, the lens core part having opposite first and second surfaces, the lens core part being divided into at least two subparts separated at least partially by at least one elongated slot extending across the lens core part between the first and second surfaces of the lens core part;

wherein the second surface of the first outer lens part and the first surface of the lens core part are fused together, the second surface of the second outer lens part and the second surface of the lens core part are fused together, and the at least one slot made through the lens core part is filled and fused with the plastic material of the first outer lens part, the lens having a lens body that is entirely filled with the plastic material in a gapless manner to prevent refraction inside the lens body of the light beams from the light source.

2. The lens as defined in claim 1 , wherein the lens includes at least one total internal reflection surface to reflect some of the light beams inside the lens.

3. The lens as defined in claim 2 , wherein the at least one total internal reflection surface is located on the first outer lens part.

4. The lens as defined in claim 1 , wherein the subparts of the lens core part have a substantially similar volume of the moldable material.

5. The lens as defined in claim 1 , wherein the lens has a central axis passing through the first and second optical active surfaces, the lens having a plane of symmetry that is coincident with the central axis.

6. The lens as defined in claim 5 , wherein the at least one slot is parallel to the plane of symmetry.

7. The lens as defined in claim 5 , wherein the at least one slot is perpendicular to the plane of symmetry.

8. The lens as defined in claim 1 , wherein the lens core part includes more than two subparts and more than one elongated slot extending across the lens core part between the first and the second surface of the lens core part.

9. The lens ( 100 ) as defined in claim 8 , wherein the slots are intersecting one another.

10. The lens as defined in claim 8 , wherein at least some of the slots are intersecting one another at right angle.

11. The lens as defined in claim 10 , wherein the slots are intersecting one another at a central axis passing through the first and second optical active surfaces.

12. The lens as defined in claim 8 , wherein at least some of the slots are rectilinear, each rectilinear slot including opposite planar walls that are substantially parallel to one another.

13. The lens as defined in claim 8 , wherein the slots are at least three in number and are radially disposed inside the lens core part.

14. The lens as defined in claim 1 , wherein the at least one slot is substantially parallel to a major axis of the lens.

15. An illumination apparatus including:

a solid state light source; and

a thick lens through which light from the solid state light source is collected, the lens being constructed as defined in claim 1 .

16. The illumination apparatus as defined in claim 15 , wherein the solid state light source includes a LED.