| 摘要 |
PURPOSE:To increase the parallel degree between light beams by equipping the device with an elliptic vessel wherein opposing ends of the electrodes are focal points, applying a reflective film to the inner surface of approximately half portion thereof in such a manner as to cover a second focal point, and disposing the vessel at a position frontward of a reflector. CONSTITUTION:A lamp 1 has an elliptic vessel 2 wherein opposing ends of arc electrodes 3, 4 are made focal points A, B. An inner surface reflective film 6 is applied to a half portion of the vessel 2 at the focal-point B side in the direction of radiation. The light beams from the focal point A pass through the vessel 2 to advance at random while the light rays from the focal point B are reflected within the lamp to be converged onto the focal point A. Namely, the arc length is considered to become just 1/2 of the original length. The lamp 1 and a parabolic reflector 5 are disposed so that a focal point of the latter corresponds to the focal point A. At this time, it is possible to radiate the parallel light beams forwards with a considerably high efficiency. |
