| 摘要 |
PURPOSE:To make it hard for impurities to enter an illumination optical system by cleaning gas circulating inside the illumination optical system during lamp cooling and to improve through-put of a device by restraining lowering of illuminance and illuminance distribution of illumination light. CONSTITUTION:This device has a chamber 1 which has a gas introduction port 1a for introducing gas, a gas exhaust port 1b for exhausting gas and a light transmitting window 1c for transmitting light, contains at least a part of an illumination optical system and is airtightly closed not to allow gas of atmosphere to enter, and a gas circulation means 9 for circulating gas whose temperature is controlled by gas temperature control means 4b, 5, 6, 7 and which is cleaned by a gas cleaning means 3 inside the chamber 1 through the gas introduction port 1a and the gas exhaust port 1b. |
