| 摘要 |
PURPOSE: To provide beam spread angle measuring instrument which can easily and accurately measure a spread angle for a flux of light emitted from a light space transmission device. CONSTITUTION: The title device is provided with angle detection systems 21, 23, 26, and 28 and 22, 24, 27, and 29 for detecting angles θ1 and θ2 of a flux of light L1 for a light axis and a spread angle detection system 30 for detecting a spread angle θ as an entire flux of light L1 based on the angle detection results θ1 and θ2 at both edges of the flux of light L1 in a direction for crossing the light axis. |
