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Lightguides having angled light extracting surfaces and specific optical absorption coefficient

  • US 10,107,951 B2
  • Filed: 05/19/2014
  • Issued: 10/23/2018
  • Est. Priority Date: 05/24/2013
  • Status: Active Grant
First Claim
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1. A lightguide centered on an optical axis and comprising a plurality of discrete light extracting structures next to and spaced apart from each other, each light extracting structure comprising a first surface extending from a first side of the lightguide and being adapted to extract light propagating in a first direction along the optical axis from an opposite second side of the lightguide by reflecting the propagating light toward the second side, the first surface making a first angle with the optical axis that is less than 45 degrees and greater than 10 degrees, the lightguide having an optical absorption coefficient of at least 0.015 cm

  • 1 at a wavelength of 500 nm and being adapted to receive an incident light having a first power and an x1 color coordinate in a range from 0.2 to 0.4 and a y1 color coordinate in a range from 0.1 to 0.4 from an input face of the lightguide, the received light propagating within the lightguide in the first direction along the optical axis and being extracted by the plurality of discrete light extracting structures and exiting the lightguide from the second side as an output light having a second power and (x2, y2) color coordinates, a ratio of the second power to the first power being at least 10%, an absolute value of a difference between x1 and x2 being no more than 0.03 and an absolute value of a difference between y1 and y2 being no more than 0.05.

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