| 摘要 |
PURPOSE:To improve the strength of the exposure light beam by forming a selective optical film which permeate the majority of the heat ray while reflecting the majority of near-infrared ray on the surface at one side of the outercircumference of a silicon glass pipe. CONSTITUTION:In place of a metal deposition film 11 formed on the surface at one side of a silicon glass pipe 3 of a forcefuly cooled super high pressure mercury lamp 2, a selective optical film 12 where the multi-layer film of CeO2 and MgF2 is formed with predetermined depth. Said film 12 is formed by controlling the depth of each deposition layer such that the reflection factor at the near ultraviolet section of 3650A is 70-90% while the relfection factor at the near infrared section is 10- 20%. The mercury is encapsulated in the pipe 3 then the high voltage is applied between the electrode terminals 6 to operate a lamp 2. With such optical film 12, the majority of the heat ray radiated from the interior of the lamp 2 will never be reflected again while the majority of the near ultraviolet ray is reflected again thus to increase the strength of the exposure light beam. Furthermore the lowering of the service life due to the temperature rise and the disturbance of the light distribution will never occur. |
