notes the current problem with laser display systems:
Another issue with laser display systems versus non-laser based display systems is the so called "speckle" problem. "Speckling" refers to an interference in the intensity of highly coherent light, such as laser light, which may result from the laser striking a rough surface. The overall effect of speckle in laser display systems is that the image may appear grainy. Furthermore, laser light sources are often more costly than other non-laser light sources, making laser based display systems more expensive.
As a solution they suggest a method for combining coherent and incoherent (e.g. LED) light sources.
Embodiments are disclosed that allow light display systems, such as projectors, to have lower power consumption, reduced speckling, and/or that are less expensive than conventional light projectors. In some embodiments, an incoherent light source may be optically coupled to a coherent light source to produce a combined coherent and incoherent beam of light for projecting images. In general, incoherent light sources, such as light emitting diodes (LEDs) or incandescent bulbs, emanate light waves across a broad spectrum (e.g., multiple wavelengths of light), whereas coherent light sources, such as lasers, are more precise and emanate light waves of a single wavelength. By combining light from the incoherent light source with the light from the coherent light source, the overall power level of the coherent light source in the combined light beam may be reduced while still perceiving a crisp, clear image. As a result of the lower power levels for the coherent light sources, the size and complexity of light projection systems may be reduced.
This application would suggest that Apple has been investigating the possibility of adding projection to at least some of its devices.
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