Patent ID: 6735227
Filing Date: 2004-05-11
Classification: G02B,H01S

Abstract:
A light source, comprising:a mounting member; electrical conductors extending from the mounting member, a light emitting device mounted on the mounting member and electrically connected to the electrical conductors, for generating light having a predetermined wavelength; two optical detectors arranged on opposite sides of the light emitting device and connected with the electrical conductors; a can mourned on the mounting member and enclosing the light emitting device and the optical detectors; and a diffraction grating fixed in the can, the diffraction grating defining a plurality of parallel grooves facing the light emitting device, each groove having a depth D, adjacent grooves being separated by a distance A, and a sum of the distance A and a width of any one groove being defined as a distance B; wherein part of light beams generated by the light emitting device we reflected by the diffraction grating, the reflected beams include at least zero order tight beams and a Â±1 order light beams, the depth D and the distances A and B are determined so that the reflected light beams concentrate on the Â±1 order light beams, and the optical detectors are located so that they collect most of the Â±1 order light beams, wherein a desired ratio of intensity of the Â±1 order light beams to the zero order light beams can be obtained by selecting a suitable depth D, distance A, and duty cycle F, wherein F=A/B; whereby when the intensity of the reflected light beams substantially concentrates on the Â±1 order light beams, the Â±1 order light beams are substantially collected by the optical detectors.