Sensing a vertical surface by measuring a fluorescence signal using a confocal optical system

Abstract

We have developed an optical technique for sensing a vertical surface by utilizing fluorescence signals. The measured surface was coated with a fluorescent dye. First, the angular range of the fluorescence emission from the surface was experimentally investigated. The experimental results revealed that the fluorescence was emitted over a wide range of angles greater than 10° from the surface, which is wide enough to enable the detection of a vertical surface. Second, the surface of a fluorescent-dye-coated silicon wafer was sensed using a fluorescent confocal optical system. The vertical surface was scanned horizontally with a laser beam, and the detected signal was found to have a specific peak of 3 µm at full width at half maximum. Thus, the vertical surface was sensed successfully by the fluorescent confocal optical system.