New UV-Detectors for the UV-A to UV-C region with high longterm stability

One important issue in UV-curing processes is the quality assurance of UV-curing applications, where an in-line control of the UV-radiation dose by continuous monitoring is highly desirable. A decrease of UV-intensity due to degradation of the lamp or contamination of the reflector can be detected at an early stage and preventive maintenance can be initiated. However, a major problem for continuous monitoring is posed by the degradation of conventional detectors made of Silicon (i.e. the corresponding filters that block visible light and IR radiation), which tend to degrade under high intensity UV-radiation. Silicon-Carbide, an alternative radiation hard material, has a bell shaped response in the UV region with a maximum sensitivity around 300 nm decreasing significantly in the UV-A region, which is most relevant for UV-curing: Typical spectral responsivity values decrease from 0.02 A/W at 365 nm down to approximately 1 x 10-5 A/W at 400 nm, requiring expensive large area detectors.