Method and system for RGB illuminator
An optical combiner includes a curved reflective element and a rotating mirror configured to rotate through a range of angular displacement. During a first time period, the curved reflective element is configured to reflect a first light beam emitted from a first light source to the rotating mirror when the rotating mirror is disposed at a first angular displacement, and the rotating mirror is configured to receive the first reflected light beam and provide a first output light beam along an output optical axis. During a second time period, the curved reflective element is configured to reflect a second light beam emitted from a second light source to the rotating mirror when the rotating mirror is disposed at a second angular displacement, and the rotating mirror is configured to receive the second reflected light beam and provide a second output light beam along the output optical axis.
1. An optical combiner comprising a curved reflective element and a rotating mirror configured to rotate through a range of angular displacement, wherein:
during a first time period, the curved reflective element is configured to reflect a first light beam emitted from a first light source to the rotating mirror when the rotating mirror is disposed at a first angular displacement, and the rotating mirror is configured to receive the first light beam and provide a first output light beam along an output optical axis;
during a second time period, the curved reflective element is configured to reflect a second light beam emitted from a second light source to the rotating mirror when the rotating mirror is disposed at a second angular displacement, and the rotating mirror is configured to receive the second light beam and provide a second output light beam along the output optical axis; and
whereby the optical combiner is configured to provide a time sequential collimated combined light beam.
2. The optical combiner of claim 1 wherein the rotating mirror is configured to dither the first output light beam and the second output light beam.
3. The optical combiner of claim 1 wherein:
the first light beam is incident on a first region on the curved reflective element; and
the second light beam is incident on a second region on the curved reflective element, wherein the second region is different from the first region.
4. The optical combiner of claim 3 wherein the curved reflective element comprises discrete prescriptions for the first region and the second region.
5. The optical combiner of claim 3 wherein the curved reflective element comprises a single prescription for the first region and the second region.
6. The optical combiner of claim 5 wherein the curved reflective element follows a prescription corresponding to the following equation:
z=cy 2 /1+√{square root over (1−(1+ k ) c 2 y 2 )}+α 1 y 2 +α 2 y 4 ++α 3 y 6 +α 4 y 8 +α 5 y 10 +α 6 y 12
where the curve of the curved reflective element is defined in z-y plane, c is the curvature of the base radius, k is the conic constant, and the coefficients α are polynomial aspheric coefficients.
7. The optical combiner of claim 6 wherein k=−1.
8. The optical combiner of claim 1 wherein the curved reflective element comprises a parabolic surface contour.
9. A method for combining light beams from multiple light sources, the method comprising:
(a) during a first time period:
receiving a first input light beam from a first light source using a curved reflective element;
reflecting, using the curved reflective element, the first input light beam to form a first reflected light beam;
disposing a rotating mirror at a first angular displacement; and
reflecting, using the rotating mirror, the first reflected light beam to provide a first output light beam along an output optical axis;
(b) during a second time period:
receiving a second input light beam from a second light source using the curved reflective element;
reflecting, using the curved reflective element, the second input light beam to form a second reflected light beam;
disposing the rotating mirror at a second angular displacement; and
reflecting, using the rotating mirror, the second reflected light beam to provide a second output light beam along the output optical axis; and
repeating (a) and (b) to provide a time sequential collimated combined output light beam along the output optical axis.
10. The method of claim 9 further comprising dithering the time sequential collimated combined output light beam using the rotating mirror.
11. The method of claim 9 wherein:
the first input light beam is incident on a first region on the curved reflective element; and
the second input light beam is incident on a second region on the curved reflective element, wherein the second region is different from the first region.
12. The method of claim 11 wherein the curved reflective element comprises discrete prescriptions for the first region and the second region.
13. The method of claim 11 wherein the curved reflective element comprises a single prescription for the first region and the second region.
14. The method of claim 13 wherein the curved reflective element follow a prescription corresponding to the following equation:
z=cy 2 /1+√{square root over (1−(1+ k ) c 2 y 2 )}+α 1 y 2 +α 2 y 4 ++α 3 y 6 +α 4 y 8 +α 5 y 10 +α 6 y 12
where the curve of the curved reflective element is defined in z-y plane, c is the curvature of the base radius, k is the conic constant, and the coefficients α are polynomial aspheric coefficients.
15. The method of claim 14 wherein k=−1.
16. The method of claim 9 wherein the curved reflective element comprises a parabolic surface contour.