Source collector apparatus, lithographic apparatus and method

The invention provides a source collector apparatus, a lithographic apparatus and a method. A source collector apparatus comprising a fuel droplet generator configured to generate a stream of fuel droplets directed from an outlet of said fuel droplet generator towards a plasma formation location, a shroud constructed and arranged to protect the stream of fuel droplets, and a detecting apparatus constructed and arranged to detect the coalescence of fuel droplets in the fuel droplet stream as it passes along said shroud. In addition, the invention also provides a method and lithographic apparatus for detecting formation of associated droplets in a stream of fuel droplets of a source collector device. 本发明提供了种源收集器设备，所述源收集器设备包括：燃料液滴生成器，配置成生成从所述燃料液滴生成器的出口朝向等离子体形成部位引导的燃料液滴流；护罩，构造和布置用于保护所述燃料液滴流；和检测设备，构造和布置用于在燃料液滴流沿着所述护罩通过时检测燃料液滴在燃料液滴流中的融合。另外，本发明还提供了种用于检测在源收集器设备的燃料液滴流中的伴生液滴的形成的方法和光刻设备。