MEASURING METHOD FOR CENTER OF LASER DIODE LIGHT-EMITTING PATTERN

PURPOSE:To measure the center point of a light emission pattern precisely by sensing the max. brightness point, and also performing sensing of the center point position due to following of an arc of circle. CONSTITUTION:When the light from an LD element 1 is photographed by an infrared camera 2 and fed to a TV monitor 5 and personal computer 8 via an image input device 7, the personal computer 8 reads the image as Step 1 and determines the max. brightness point in the screen. In Step 2, brightnesses in eight directions from the max. brightness point are measured, and judgement is made whether the place is the center point of the circle - if not, proceed to Step 3 in which this point is used as a part of a ring, and the maximum point is determined in the max. brightness point direction of the surrounding, and the circle is pursued. At Step 4, three points on the circumferential coordinate of circle constitute one set, and a plurality of such sets are selected, and the center coordinate is calculated for each set, and the center point is determined from the mean of them. Circular judgement is made again, and thus optical axis adjustment between the lens system and LD can be done.