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1. (WO2002007230) LIGHT EMITTING DIODES

Pub. No.:    WO/2002/007230    International Application No.:    PCT/GB2001/003225
Publication Date: Jan 24, 2002 International Filing Date: Jul 18, 2001
IPC: H01L 33/20
Applicants: QINETIQ LIMITED
GORDON, Neil, Thomson
ELLIOTT, Charles, Thomas
SMITH, Stanley, Desmond
KARPUSHKO, Fedor, Vladimir
HARDAWAY, Harvey
Inventors: GORDON, Neil, Thomson
ELLIOTT, Charles, Thomas
SMITH, Stanley, Desmond
KARPUSHKO, Fedor, Vladimir
HARDAWAY, Harvey
Title: LIGHT EMITTING DIODES
Abstract:
To increase the amount and/or directionality of light from a light emitting diode (LED) 1 supported on a substrate 2, the side of the diode remote from the substrate is provided with an additional layer 5 in which is formed a diffractive (grating) or interference (Fresnel lens) optical elemental 4 of varying thickness. The construction is particularly useful in the infra-red, where the thickness variation cannot be built into the LED structure itself. Layer may be formed during manufacture of the LED, or secured thereto by an optically thin layer of adhesive.