The use of fibre optics as light guidance allows a great modularity and flexibility in the setup of an optical measurement system. Optical fibres can be made of many materials, such as plastic, glasses, and silicates (SiO2). For high-quality fibre optics, as used in spectroscopic applications, synthetic fused silica (amorphous silicon dioxide) is used, which can be intentionally doped with trace elements to adjust the optical properties of the glass.