Illumination light source device
AssigneeNikon Corporation
InventorsTsuyoshi Naraki, Haruo Ozawa, Takashi Mori, Jun Nagatsuka
Life of this patent
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Abstract
A light source device houses a lamp such as a mercury discharge tube for generating a high temperature heat, and a reflective optical member such as an elliptic, mirror surrounding the lamp, in a lamp case. When the lamp is forcibly cooled by air, a device for substantially uniformly heating or heat-insulating a reflection surface of the reflective optical member is provided to prevent overcooling of the reflective optical member.
Claims20
A light source device for irradiating an object, comprising:
- a lamp operable for emitting light, said lamp creating heat during the emission of light;
- an optical member disposed near said lamp for directing light from said lamp toward said object;
- means for supplying cooling gas to a space between said lamp and said optical member for cooling said lamp;
- and
- means for controlling the temperature of said optical member,
- said optical member, in the absence of said temperature controlling means, being subject to a reduction in its ability to direct light from said lamp toward said object, due to deposition of a contaminant on said optical member, said contaminant having a decomposition temperature at which deposition of said contaminant on said optical member is prevented and below which such deposition occurs, said temperature controlling means setting the temperature of said optical member, during the operation of said lamp, at a temperature level that is at least as high as said decomposition temperature.
A light source device for radiating an illumination light onto an object, comprising:
- a lamp for emitting an illumination light;
- a reflective optical member having a front side disposed near said lamp and including a reflection surface for reflecting said illumination light toward said object, said reflective optical member having a heat resistive temperature which is above a decomposition temperature of a sulfuric acid derived compound;
- means for supplying cooling gas to a space between said lamp and said reflective optical member to forcibly cool said lamp;
- and
- means provided on a rear side of said reflective optical member electrically heating the reflection surface of said reflective optical member to a temperature which is above said decomposition temperature and less than said heat resistive temperature in order to prevent deposition of said sulfuric acid derived compound on the reflection surface of said reflective optical member, which might otherwise occur due to influence of said illumination light and heat from said lamp and cooling of said reflective optical member by said cooling gas.
An exposure apparatus for exposing a pattern formed on a mask onto a photosensitive member with an illumination light from an illumination system, said illumination system comprising:
- a lamp for emitting an illumination light;
- a reflective optical member having a front side disposed near said lamp and including a reflection surface for reflecting said illumination light toward an object, said reflective optical member having a heat resistive temperature which is above a decomposition temperature of a sulfuric acid derived compound;
- means for supply cooling gas to a space between said lamp and said reflective optical member to forcibly cool said lamp;
- means provided on a rear side of said reflective optical member electrically heating the reflection surface of said reflective optical member to a temperature which is above said decomposition temperature and less than said heat resistive temperature in order to prevent deposition of said sulfuric acid derived compound on the reflection surface of said reflective optical member, which might otherwise occur due to influence of said illumination light and heat from said lamp and cooling of said reflective optical member by said cooling gas.
Dependencies are inferred from the claim text.