| 摘要 |
PROBLEM TO BE SOLVED: To enhance the uniformity ratio of illuminance by reducing the rate of nonuniform illuminance of illuminating light over a wide angle area in which the illuminating angle is not less than 23 deg.. SOLUTION: A lamp 3 is placed at one end over an optical axis 2 in the illuminating direction. A reflector 4 by which part of light rays emitted from the lamp 3 is reflected in the illuminating direction is placed. An illuminating lens 6 with an illuminating angle as wide as 23 deg. or more and with a diameter ranging between 125 and 200mm is placed at the other end over the optical axis 2 in the illuminating direction. When the diameter of the illuminating lens 6 is less than 125mm, nonuniform illuminance of the illuminating light becomes conspicuous over a wide angle area in which the illuminating angle is not less than 23 deg., and if the diameter exceeds 200mm, the wide angle lens becomes difficult to fabricate. |
