采用聚焦毛细管将通用的极紫外光源引出法兰口之外，并控制光束发散角，以匹配平行光管孔径角。分析计算了直接用光源照亮靶盘的情形，光束不能充满有效主镜面上的直径；设计使用聚焦毛细管，使光束充满平行光管孔径角，并对极紫外平行光管有无毛细管两种状态进行测试。测试结果表明，采用聚焦毛细管后，扩大了光束的发散角，并且无毛细管的最大光子计数接近1×105个，加毛细管后最大光子计数能达到1×104个。测试数据说明极紫外聚焦毛细管的传输效率可以达到10%，能够满足极紫外平行光管的各项技术指标要求。

Through using focusing capillary, the extreme ultraviolet (EUV) light source of collimator is channelled out of flange, and the light beam′s divergence angle is controlled to match the collimator′s aperture angle. This article analyzes and calculates the case of directly using a light source to illuminate target disk and the light beam cannot cover the diameter of the effective primary mirror. Focusing capillary can make the light beam cover the aperture angle of collimator and the two states of the EUV collimator with and without capillary are tested.The results show that using focusing capillary can expand light beam′s divergence angle. Besides, the maximum number of photons without capillary is close to 1×105 and the maximum number of photons with capillary can reach 1×104. The testing data show that the EUV focusing capillary′s transmission efficiency can achieve 10% to meet technical index of EUV collimator.