Optical extender for vehicle heads up displays

1. A vehicle comprising:

a windshield; and

a heads up display system including:

an image source to provide a projection image;

a main mirror to project the projection image onto the windshield, the image source and the main mirror defining a light path; and

an optical extender between the main mirror and the windshield, the optical extender having a multi-polynomial top surface that modifies light in the light path to, when the light in the light path intersects the windshield, create an optical path wherein a virtual image of the projection image is visible from an eyebox defined within a cabin of the vehicle,

wherein the optical extender includes a diffractive layer on the multi-polynomial top surface.

2. The vehicle of claim 1 , wherein the optical path defines a projection distance from the eyebox to a perceived location of the virtual image in front of the vehicle.

3. The vehicle of claim 2 , wherein the projection distance is at least seven meters.

4. The vehicle of claim 1 , therein the multi-polynomial top surface of the optical extender has an apex and a nadir.

5. The vehicle of claim 1 , wherein the multi-polynomial top surface of the optical extender has a plurality of at least one of apexes or nadirs.

6. The vehicle of claim 1 , wherein the optical extender does not have a uniform thickness.

7. The vehicle of claim 6 , wherein a thickness of the optical extender decreases from a first edge to a second edge of the optical extender, the second edge of the optical extender being closer to the windshield.

8. The vehicle of claim 1 , wherein the multi-polynomial top surface is configure for the vehicle.

9. The vehicle of claim 1 , wherein the optical extender includes a first layer made of a first material and a second layer made of a second material, the second material being different than the first material.

10. The vehicle of claim 9 , wherein the first layer is an achromatic layer.

11. A heads up display system for a vehicle comprising:

an image source to provide a projection image;

a main mirror to redirect and magnify the projection image towards an aspheric surface of the vehicle, the image source and the main mirror defining a light path that extends to the aspheric surface; and

an optical extender between the main mirror and the aspheric surface within the light path, the optical extender having a multi-polynomial top surface that modifies light in the light path to, when the light in the light path intersects the aspheric surface, create an optical path wherein a virtual image of the projection image is visible from an eyebox defined within a cabin of the vehicle,

wherein the optical extender includes a first layer made of a first material and a second layer made of a second material, the second material being different than the first material and wherein the first layer is an achromatic layer.

12. The heads up display system of claim 11 , wherein the optical path defines a projection distance from the eyebox to a perceived location of the virtual image in front of the vehicle.

13. The heads up display system of claim 12 , wherein the projection distance is at least seven meters.

14. The heads up display system of claim 11 , therein the multi-polynomial top surface of the optical extender has an apex and a nadir.

15. The heads up display system of claim 11 , wherein the multi-polynomial top surface of the optical extender has a plurality of at least one of apexes or nadirs.

16. The heads up display system of claim 11 , wherein the optical extender does not have a uniform thickness.

17. The heads up display system of claim 16 , wherein a thickness of the optical extender decreases from a first edge to a second edge of the optical extender, the second edge of the optical extender being closer to the aspheric surface.