Laser illumination on phosphor for projection display

1. An apparatus for image projection comprising:

a laser providing a first color light;

a plurality of dichroic polarizing beam splitters (DPBSs), each DPBS operable to split the first color light into a first beam and a second beam in dependence on the polarization of the first color light;

a plurality of switchable half-wave plates, each switchable half-wave plate being paired with a respective DPBS and positioned between the laser and the respective DPBS;

a quarter-wave plate backed by a mirror and positioned to receive a first beam from a respective DPBS, the beam that is reflected from the mirror being directed towards an output by at least the respective DPBS; and

a plurality of static phosphor devices, each static phosphor device positioned to receive one of the first beam and the second beam from a respective DPBS and to emit light in a respective color, the emitted light being directed towards the output by one or more of the DPBSs.

2. The apparatus as recited in claim 1 wherein the first color light is blue.

3. The apparatus as recited in claim 1 further comprising a computer chip connected to control the plurality of switchable half-wave plates, the computer chip containing a processor and instructions stored on the computer chip that when executed by the processor, switch the plurality of switchable half-wave plates such that during a first period the first color light is directed toward the quarter-wave plate backed by the mirror, during a second period the first color light is directed toward a first phosphor device of the plurality of phosphor devices and during a third period the first color light is directed toward a second phosphor device of the plurality of phosphor devices.

4. The apparatus as recited in claim 3 wherein the instructions when executed by the processor further switch the plurality of switchable half-wave plates such that during a fourth period the first color light is directed toward a third phosphor device of the plurality of phosphor devices.

5. The apparatus as recited in claim 3 further comprising:

a first homogenizer located in the path of the first beam from the DPBS of the plurality of DPBSs nearest the lasers; and

a second homogenizer located in the path of the second beam from the DPBS nearest the lasers.

6. A method of operating a projection system that uses a laser, the method comprising:

directing a first color light towards a first dichroic polarizing beam splitter (DPBS) of a plurality of DPBSs, each additional DPBS of the plurality of DPBSs being situated to receive a beam from a DPBS that is closer to the laser;

controlling a plurality of switchable half-wave plates such that during a first period the first color light is directed toward a quarter-wave plate backed by a mirror, during a second period the first color light is directed toward a first static phosphor device, and during a third period the first color light is directed toward a second static phosphor device; and

directing the light returning from the quarter-wave plate and from first and second static phosphor devices toward an output.

7. The method as recited in claim 6 further comprising:

homogenizing a first beam and a second beam of the first color light from the first DPBS.

8. The method as recited in claim 6 further comprising:

controlling the plurality of switchable half-wave plates such that during one or more additional periods the first color light is directed toward respective additional static phosphor devices.