Raster reordering in laser projection systems
Techniques are described for reducing safety-relevant emission of a laser projection system. A multi-facet optical element is positioned in the path of a raster-scanning laser beam. Each facet of the optical element is angled to redirect a projected pixel to a different pixel position. Collectively, the facets are configured to convert the projected raster scan into a non-raster scan in which physically proximate pixels are illuminated temporally non-proximate times.
1. An optical projection system comprising:
an image source configured to generate a source image, the source image comprising a plurality of pixels in a first order for projection onto a display surface at associated pixel positions;
a processing component configured to reorder the pixels of the source image in a second order to produce a reordered image;
a projection source configured to direct a laser beam that projects the reordered pixels of the reordered image in a raster sequence; and
an optical element positioned in a path of the laser beam, the optical element having multiple facets, wherein each of the facets is configured to redirect light of a particular projected pixel of the reordered image to its associated pixel position on the display surface such that the plurality of pixels of a resulting image on the display surface is ordered in the first order.
2. The optical projection system of claim 1 , wherein the multiple facets are configured to redirect the laser beam in a non-contiguous sequence of the pixel positions.
3. The optical projection system of claim 1 , wherein the multiple facets are configured to reduce a continuous energy density emitted by the laser beam when measured across a measurement area of a predefined size.
4. The optical projection system of claim 1 , wherein the optical element is stationary relative to the projection source.
5. The optical projection system of claim 1 , wherein the optical element has a facet corresponding to each of the pixel positions.
6. The optical projection system of claim 1 , wherein each facet of the optical element corresponds to a plurality of the pixel positions.
7. The optical projection system of claim 1 , wherein the pixel positions have a first horizontal-to-vertical ratio and the facets of the optical element have a second, different horizontal-to-vertical ratio.
8. The optical projection system of claim 1 , wherein individual facets of the optical elements are non-planar.
9. The optical projection system of claim 1 , wherein the optical element comprises a mirror.
10. The optical projection system of claim 1 , wherein the optical element comprises a lens.
11. A method comprising:
generating, by an image source, a source image, the source image comprising a plurality of pixels in a first order for projection onto a display surface at associated pixel positions;
reordering, by a processing component, the pixels of the source image in a second order to produce a reordered image;
directing, by a projection source, a laser beam that projects the reordered pixels of the reordered image in a raster sequence; and
redirecting, by each facet of multiple facets of an optical element positioned in a path of the laser beam, light of a particular projected pixel of the reordered image to its associated pixel position on the display surface such that the plurality of pixels of a resulting image on the display surface is ordered in the first order.
12. The method of claim 11 , wherein the laser beam is redirected in a non-contiguous sequence of the pixel positions.
13. The method of claim 11 , wherein the pixel positions have a first horizontal-to-vertical ratio and the facets of the optical element have a second, different horizontal-to-vertical ratio.
14. The method of claim 11 , wherein individual facets of the optical elements are non-planar.
15. The method of claim 11 , wherein the optical element comprises a mirror.
16. The method of claim 11 , wherein the optical element comprises a lens.
17. An optical projection system comprising:
one or more processors;
a memory;
instructions stored in the memory that, when executed by the one or more processors, cause the one or more processors to:
generate a source image, the source image comprising a plurality of pixels in a first order for projection onto a display surface at associated pixel positions;
reorder the pixels of the source image in a second order to produce a reordered image;
direct a laser beam that projects the reordered pixels of the reordered image in a raster sequence; and
an optical element positioned in a path of the laser beam, the optical element having multiple facets, wherein each of the facets is configured to redirect light of a particular projected pixel of the reordered image to its associated pixel position on the display surface such that the plurality of pixels of a resulting image on the display surface is ordered in the first order.
18. The optical projection system of claim 17 , wherein the multiple facets are configured to redirect the laser beam in a non-contiguous sequence of the pixel positions.
19. The optical projection system of claim 17 , wherein the multiple facets are configured to reduce a continuous energy density emitted by the laser beam when measured across a measurement area of a predefined size.
20. The optical projection system of claim 17 , wherein the optical element is stationary relative to a projection source.
21. The optical projection system of claim 17 , wherein the optical element has a facet corresponding to each of the pixel positions.
22. The optical projection system of claim 17 , wherein each facet of the optical element corresponds to a plurality of the pixel positions.
23. The optical projection system of claim 17 , wherein the pixel positions have a first horizontal-to-vertical ratio and the facets of the optical element have a second, different horizontal-to-vertical ratio.