| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical device that has an insulating property high enough to withstand high voltage application in starting a discharge lamp, has a long life, does not deteriorate the reflecting efficiency of a concave reflecting mirror and can improve the light utilization efficiency in a compact optical device that uses a short arc-type discharge lamp and has high luminous energy. SOLUTION: This optical device is formed by combining a short arc-type discharge lamp where sealing parts 2 are formed at both sides of a swelled part 1a located at the center of a luminescent tube 1, a spherical surface having a central hole 7 at its rear center, a concave reflecting mirror 4 composed of such as a parabolic or an elliptic surface, and one of the sealing parts of the discharge lamp with the central hole 7. In this case, the diameter of the central hole 7 is formed generally less than the maximum diameter of the swelled part 1a of the luminescent tube and a lead wire 9 stretching from the sealing part of the discharge lamp located at the opening side of the concave reflecting mirror 4 is inserted into a small hole 5 formed at a part close to the center of the reflecting mirror 4, the lead wire 9 stretching from the sealing part of the discharge lamp secured in the central hole 7 and the lead wire 9 inserted into the small hole 5 are placed almost in parallel with each other at the back of the concave reflecting mirror 4, and each of the lead wires 9 is coated with an insulating material. |
