METHOD FOR EVALUATING CHARACTERISTIC OF HOLOGRAM

摘要

PURPOSE:To accurately measure a Bragg angle by making incident plural laser lights upon a hologram surface crossing on the hologam surface and installing an optical detector closely to each optical path of the diffracted lights of the same specified degree of the plural laser lights. CONSTITUTION:Two laser lights L1 and L2 are made incident upon a hologram 3 crossing at an intersecting angle or gamma on the halogram 3. To detect the diffracted lights D1 and D2 of the laser lights L1 and L2 by the hologram 3, the optical detectors S1 and S2 are installed and the angle formed by the optical detectors S1 and S2 and a point O is made almost equal to the intersecting angle gamma. When the diffracted lights D1 and D2 are detected with the hologram 3 being rotated around the point O in the direction of arrow, a certain condition allows the output valves of one optical detector S1 equals to that of the other S2 to obtain a Bragg angle by the incident angle from the bisector direction of the intersecting angle gamma of the laser lights L1 and L2 under this condition.