There currently exists a demand for electronic devices capable of emitting light with low etendue. Etendue is a measure of how a light beam spreads in area and angle as it propagates. Low etendue light may be characterized by minimal spreading of a light beam over distance such as in, for example, laser light. Devices that emit low etendue light may be employed in a variety of optical display or projection systems. One such device generates high luminance colored light sources utilizing focused or tightly-collimated laser excitation. For example, laser-activated remote phosphor (LARP) devices may generate a low etendue light emission by converting the light from an incident laser beam into a longer wavelength emission (so-called down-conversion) by employing a phosphor target. However, at least one issue with LARP devices is the heat generated by the down-conversion (Stokes shift) and other non-radiative losses within the phosphor that may lead to degradation or thermal quenching of the phosphor. Existing LARP devices may employ mechanical means such as, for example, phosphor powder embedded in silicone on a rotating and reflective color wheel to avoid overheating by minimizing duty cycle. However, this approach requires additional mechanical components that must maintain very tight tolerances, and large amounts of phosphor. Alternative approaches employ luminescent ceramic plates attached to heat conductive substrates with heat-resistant silicone adhesives. This solution is also problematic in that the silicone adhesives that maintain the optical transparency needed in LARP devices are poor heat conductors, and thus, overheating remains a problem.
USPTO Backgrounds
USPTO Backgrounds