Solar-irradiated leakage of UV camera for daytime corona inspection

Among various parameters impacting on the performance of UV camera for daytime corona inspection, the solar-irradiated leakage (SIL) is the most influential one according to the BLUP theory. The minimum detectable corona is limited by √(SIL). In this paper, a series of UV filters are used to represent different SIL levels on a clear day. After a UV filter with a transmittance of 10^-13 above 300 nm being applied, the SIL can be effectively suppressed rapidly below 25 photoelectrons per second. Using the 10^-13 UV filter, a 1μW weak corona defect can be identified over 100m on a clear day with the help of a proper spatial and temporal correlation algorithm.