Folded-beam, low-obliquity beam scanner
A beam scanner includes a substrate, a tiltable reflector hingedly supported by the substrate, and a reflective polarizer. The reflective polarizer is supported over the tiltable reflector and configured to receive and redirect a light beam towards the tiltable reflector for scanning the light beam. A projector includes the beam scanner and a light source providing a light beam. The light beam may be modulated in brightness, color, or polarization synchronously with tilting the reflector, thereby forming an image in angular domain after propagating through a pupil-replicating waveguide. At least one folding mirror may be provided for directing the light beam from the light source around the pupil-replicating waveguide, resulting in a compact overall configuration.
1. A display comprising:
a light source for providing a light beam having a characteristic comprising at least one of brightness or color;
a beam scanner comprising:
a substrate;
a tiltable reflector hingedly supported by the substrate;
a first folding mirror extending from the substrate, wherein the first folding mirror is configured to receive and redirect the light beam; and
a reflective polarizer supported over the tiltable reflector and configured to receive the light beam from the first folding mirror and to further redirect the light beam towards the tiltable reflector for scanning the light beam; and
a waveguide configured to receive the light beam reflected from the tiltable reflector, and to spread the light beam over an eyebox of the display;
wherein the light source and the beam scanner are disposed on opposite sides of the waveguide.
2. The display of claim 1 , wherein the waveguide is substantially parallel to the substrate of the beam scanner.
3. The display of claim 1 , further comprising a second folding mirror configured to receive and redirect the light beam towards the first folding mirror and around the waveguide.
4. The display of claim 1 , further comprising a controller operably coupled to the light source and the beam scanner for varying the characteristic of the light beam in coordination with scanning the light beam by the beam scanner.
5. The display of claim 1 , further comprising a quarter-wave waveplate (QWP) in an optical path between the reflective polarizer and the tiltable reflector, wherein the QWP is configured to change a polarization state of the light beam to an orthogonal polarization state upon double pass propagation of the light beam through the QWP.
6. The display of claim 5 , wherein the QWP is supported by the reflective polarizer.
7. The display of claim 1 , wherein the beam scanner further comprises an enclosure of the tiltable reflector and the first folding mirror.
8. The display of claim 7 , wherein the enclosure comprises a hermetic enclosure.
9. The display of claim 7 , wherein the enclosure comprises an optical window in an optical path upstream of the first folding mirror.
10. The display of claim 1 , wherein the tiltable reflector is tiltable about two orthogonal axes.
11. The display of claim 1 , wherein the tiltable reflector comprises a microelectromechanical system (MEMS) tiltable reflector.
12. The display of claim 1 , wherein the light source comprises a laser diode.
13. The display of claim 1 , wherein the light source comprises a multi-emitter assembly.