Compact multi-color beam combiner using a geometric phase lens

1. A multi-color light source device, comprising:

a first light source configured to emit light of a first color;

a second light source configured to emit light of a second color that is distinct from the first color; and

a first geometric phase lens associated with a first focal length for the light of the first color and a second focal length, distinct from the first focal length, for the light of the second color, wherein:

the first light source is located at a first distance from the first geometric phase lens;

the second light source is located at a second distance, distinct from the first distance, from the geometric phase lens, and

the first light source, the second light source, and the first geometric phase lens are positioned so that the light of the first color and the light of the second color, after passing through the first geometric phase lens, and collinear and have a corresponding divergence.

2. The device of claim 1 , wherein:

the first light source, the second light source, and the first geometric phase lens are positioned so that the light of the first color and the light of the second color, after passing through the first geometric phase lens, are collinearly collimated.

3. The device of claim 1 , wherein:

the first distance corresponds to the first focal length; and

the second distance corresponds to the second focal length.

4. The device of claim 1 , wherein:

a first portion of the first geometric phase lens corresponds to a first half-wave plate having a first axis and a second portion of the first geometric phase lens corresponds to a second half-wave plate having a second axis that is not parallel to the first axis.

5. The device of claim 4 , wherein:

the first geometric phase lens includes a substrate coated with one or more layers of polymerized liquid crystals.

6. The device of claim 4 , wherein:

the first geometric phase lens includes a substrate with a plurality of nanopillars.

7. The device of claim 1 , wherein:

the first color is red; and

the second color is green.

8. The device of claim 1 , wherein:

an exit pupil of the first light source is located at the first distance from the first geometric phase lens; and

an exit pupil of the second light source is located at the second distance from the first geometric phase lens.

9. The device of claim 1 , further comprising:

a third light source configured to emit light of a third color that is distinct from the first color and the second color, wherein:

the first geometric phase lens is associated with a third focal length, distinct from the first focal length and the second focal length, for the light of the third color; and

the third light source is located at a third distance, distinct from the first distance and the second distance, from the first geometric phase lens.

10. The device of claim 9 , further comprising:

two or more dichroic mirrors, including:

a first dichroic mirror configured to direct light from the first light source toward the first geometric phase lens; and

a second dichroic mirror configured to direct light from the second light source toward the first geometric phase lens.

11. The device of claim 10 , further comprising:

a reflector configured to direct light from the third light source toward the first geometric phase lens.

12. The device of claim 9 , further comprising:

a fourth light source configured to emit light of a fourth color that is distinct from the first color, the second color, and the third color, wherein:

the first geometric phase lens is associated with a fourth focal length, distinct from the first focal length, the second focal length, and the third focal length, for the light of the fourth color; and

the fourth light source is located at a fourth distance, distinct from the first distance, the second distance, and the third distance, from the first geometric phase lens.

13. The device of claim 9 , wherein:

an exit pupil of the first light source is located at the first distance from the first geometric phase lens;

an exit pupil of the second light source is located at the second distance from the first geometric phase lens; and

an exit pupil of the third light source is located at a third distance, distinct from the first distance and the second distance, from the first geometric phase lens.

14. The device of claim 9 , further comprising:

a quarter-wave plate configured for transmitting the light of the first color from the first light source, the light of the second color from the second light source, and the light of the third color from the third light source prior to the light of the first color, the light of the second color, and the light of the third color impinging on the first geometric phase lens.

15. The device of claim 14 , wherein:

the quarter-wave plate is configured to convert the light of the first color having a linear polarization into the light of the first color having a circular polarization, convert the light of the second color having a linear polarization into the light of the second color having a circular polarization, and convert the light of the third color having a linear polarization into the light of the third color having a circular polarization.

16. The device of claim 9 , further comprising:

a first quarter-wave plate that is configured to convert the light of the first color having a linear polarization into the light of the first color having a circular polarization;

a second quarter-wave plate that is distinct and separate from the first quarter-wave plate and configured to convert the light of the second color having a linear polarization into the light of the second color having a circular polarization; and

a third quarter-wave plate that is distinct and separate from the first quarter-wave plate and the second quarter-wave plate and configured to convert the light of the third color having a linear polarization into the light of the third color having a circular polarization.

17. The device of claim 1 , further comprising:

a second geometric phase lens associated with a fourth focal length for the light of the first color and a fifth focal length, distinct from the fourth focal length, for the light of the second color, wherein:

the first light source is located at a fourth distance from the second geometric phase lens; and

the second light source is located at a fifth distance, distinct from the fourth distance, from the second geometric phase lens.

18. The device of claim 17 , wherein:

the second geometric phase lens is associated with a sixth focal length, distinct from the fourth focal length and the fifth focal length, for the light of the third color; and

the third light source is located at a sixth distance, distinct from the fourth distance and the fifth distance, from the second geometric phase lens.

19. A head-mounted display system, comprising:

the multi-color light source device of claim 1 ;

a light modulator configured for modulating light from the multi-color light source device; and

one or more lenses configured for directing modulated light from the light modulator toward an eye of a user.

20. A method, comprising:

transmitting, from a first light source, light of a first color through a first geometric phase lens associated with a first focal length for the light of the first color;

transmitting, from a second light source that is distinct and separate from the first light source, light of a second color that is distinct from the first color through the first geometric phase lens associated with a second focal length, distinct from the first focal length, for the light of the second color;

transmitting, from a third light source that is distinct and separate from the first light source and the second light source, light of a third color that is distinct from the first color and the second color through the first geometric phase lens associated with a third focal length, distinct from the first focal length and the second focal length, for the light of the third color,

whereby the light of the first color, the light of the second color, and the light of the third color, after passing through the first geometric phase lens, are collinear and have a corresponding divergence.