Patent Number: 
Section: claims

1. A differential evacuation system comprising:a light generation chamber that generates EUV (Extreme Ultra Violet) light;an illumination optical chamber in which optical processing is performed by using the EUV light;a light converging mirror arranged in the light generation chamber and converging the EUV light thus generated;a chamber connecting passage that connects together the light generation chamber and the illumination optical chamber to allow the EUV light to pass therethrough;an optical element arranged in the illumination optical chamber and reflecting the EUV light that has passed through the chamber connecting passage;a flow path constricting portion provided in the chamber connecting passage and obstructing a gas to pass therethrough; said flow path constriction portion with a smallest inner diameter and being increased in inner diameter in a conical tube shape at portions thereof that are at opposite sides, respectively, of said flow path constriction portion; andone or a plurality of vacuum pumps disposed in a position closer to the light generation chamber than the flow path constricting portion and evacuating the chamber connecting passage. 2. The differential evacuation system of claim 1, further comprising one or a plurality of pipes connected to a position of the chamber connecting passage that is closer to the light generation chamber and the flow path constricting portion,wherein the one or the plurality of vacuum pumps are connected to the one or the plurality of pipes. 3. The differential evacuation system of claim 1, further comprising a gas introducing device that feeds a gas onto a surface of the light converging mirror. 4. The differential evacuation system of claim 1,wherein the gas fed onto the surface of the light converging mirror contains He, Ne, or Ar. 5. The differential evacuation system of claim 1,wherein the gas fed onto the surface of the light converging mirror contains hydrogen. 6. The differential evacuation system of claim 1, further comprising a magnetic field generation device that generates a magnetic field around the light converging mirror. 7. The differential evacuation system of claim 1,wherein the light generation chamber is provided with a laser transmitting window for introducing laser light into the light generation chamber. 8. A differential evacuation system comprising:a light generation chamber that generates light;an illumination optical chamber in which optical processing is performed by using the light generated in said light generation chamber; anda chamber connecting passage serving as a light passage that connects together said light generation chamber and illumination optical chamber to guide the light generated in the light generation chamber into the illumination optical chamber;said chamber connecting passage having a flow path constricting portion with a smallest inner diameter and being increased in inner diameter in a conical tube shape at portions thereof that are at opposite sides, respectively, of said flow path constricting portion;wherein one or a plurality of vacuum pumps are attached to each of the portions that are at opposite sides, respectively, of said flow path constricting portion. 9. The differential evacuation system of claim 8, wherein the portions of said chamber connecting passage that are at opposite sides, respectively, of the flow path constricting portion are provided with enlarged-diameter parts, respectively, said one or plurality of vacuum pumps being attached to each of the enlarged-diameter parts. 10. The differential evacuation system of claim 9, wherein said plurality of vacuum pumps are attached to a side of each of said enlarged-diameter parts. 11. The differential evacuation system of claim 9, wherein said plurality of vacuum pumps are attached to an outer peripheral surface of each of said enlarged-diameter parts. 12. The differential evacuation system of claim 8, wherein one or a plurality of pipes are connected to each of the portions of said chamber connecting passage that are at opposite sides, respectively, of the flow path constricting portion, said vacuum pumps being attached to the pipes, respectively. 13. A differential evacuation system comprising:a light generation chamber that generates light;an illumination optical chamber in which optical processing is performed by using the light generated in said light generation chamber; anda chamber connecting passage serving as a light passage that connects together said light generation chamber and illumination optical chamber to guide the light generated in the light generation chamber into the illumination optical chamber;said chamber connecting passage having a flow path constricting portion with a smallest inner diameter and being increased in inner diameter from the flow path constricting portion toward at least one of the light generation chamber and the illumination optical chamber;wherein an enlarged-diameter part is provided at an intermediate position of the chamber connecting passage, and one or a plurality of vacuum pumps are attached to the enlarged-diameter part. 14. The differential evacuation system of claim 13, wherein said plurality of vacuum pumps are attached to a side of said enlarged-diameter part. 15. The differential evacuation system of claim 13, wherein said plurality of vacuum pumps are attached to an outer peripheral surface of said enlarged-diameter part.