Patent ID: 9464779
Filing Date: 2016-10-11
CPC Classification: F21K,F21V,F21Y,G02B,G02F,H04N

Claim Text:
1. An illumination device comprising: a first light source characterized by a first wavelength; a second light source characterized by said first wavelength; a collimating lens; and a first Bragg grating formed by means of a first recording beam incident at a first angle to said grating and a second recording beam incident at a second angle to said grating; wherein said lens collimates and directs light from said first light source towards said grating at said first angle; wherein said lens collimates and directs light from said second light source towards said grating at said second angle; wherein said first angle lies within the angular range within which the diffraction efficiency of said grating varies between predefined minimum values and a predefined maximum value, wherein said second angle lies near to a limit of said angular range, wherein the propagation direction of the diffracted portion of light incident on said grating at said first angle and the propagation direction of the non-diffracted portion of light incident on said grating at said second angle are approximately collinear; and wherein first grating diffracts said second angle light.