Abstract: A method includes generating light in a light generating chamber, causing a portion of the generated light to pass through a tube having a roughened inner surface, and detecting the portion of the generated light that has passed through the tube using a photodetector. The roughened inner surface of the tube has a surface roughness sufficient to cause grazing incidences of light to be eliminated rather than to be reflected off the roughened inner surface. In one example, the method includes outputting a signal from the photodetector to a controller, with the signal corresponding to the detected portion of the generated light. The light generated in the light generating chamber can be extreme ultraviolet (EUV) light. In tests using roughened and non-roughened protection tubes, the roughened tube was found to minimize or essentially eliminate the contribution to EUV energy from grazing incidence reflections off the inner surface of the tube.

Abstract: A method includes generating light in a light generating chamber, causing a portion of the generated light to pass through a tube having a roughened inner surface, and detecting the portion of the generated light that has passed through the tube using a photodetector. The roughened inner surface of the tube has a surface roughness sufficient to cause grazing incidences of light to be eliminated rather than to be reflected off the roughened inner surface. In one example, the method includes outputting a signal from the photodetector to a controller, with the signal corresponding to the detected portion of the generated light. The light generated in the light generating chamber can be extreme ultraviolet (EUV) light. In tests using roughened and non-roughened protection tubes, the roughened tube was found to minimize or essentially eliminate the contribution to EUV energy from grazing incidence reflections off the inner surface of the tube.

Abstract: A light source includes a light generating chamber and a collector disposed in the light generating chamber. A target material generator configured to propel a quantity of target material toward an irradiation region is disposed in front of a reflective surface of the collector. A plurality of photodetector modules is disposed external to the light generating chamber, with each of the photodetector modules being directed toward the irradiation region. A plurality of tubes is disposed between a corresponding photodetector module and the irradiation region. Each tube has a centerline directed toward the irradiation region, and each tube has a roughened inner surface. The surface roughness of the roughened inner surface is sufficient to cause grazing incidences of light to be eliminated rather than to be reflected off the roughened inner surface. A method of generating light and a method of measuring light energy also are described.

Abstract: A light source includes a light generating chamber and a collector disposed in the light generating chamber. A target material generator configured to propel a quantity of target material toward an irradiation region is disposed in front of a reflective surface of the collector. A plurality of photodetector modules is disposed external to the light generating chamber, with each of the photodetector modules being directed toward the irradiation region. A plurality of tubes is disposed between a corresponding photodetector module and the irradiation region. Each tube has a centerline directed toward the irradiation region, and each tube has a roughened inner surface. The surface roughness of the roughened inner surface is sufficient to cause grazing incidences of light to be eliminated rather than to be reflected off the roughened inner surface. A method of generating light and a method of measuring light energy also are described.