Corona discharge is a weak UV emitter; sensitivity is therefore the most important property of an optical corona detector. Three elements determine the sensitivity of a daytime corona detecting camera: colleting area, UV Filter Quality, Image intensifier.
The sensitivity of the UV channel of a corona camera is depicted by the number of UV signals generated per 100 photon arriving to the camera window within its field of view. According to our calculations, the efficiency of the UV channel is about 3% namely; about three signals will be generated as UV spots from 100 UV photons. A combination of the special optics, quality filters and superb image intensifier, as implemented in the DayCor, makes it the most sensitive corona camera in the market.
Collecting Area
The lens' area that collects UV light from the source (corona in this case) needs to be large. The larger the collecting area of the UV lens, the more UV light gets in and the more sensitive is the corona camera.
The UV lenses of the DayCorŽ camera have about four times larger UV light collection area than commercial UV lenses. The lenses were designed by Ofil and are Ofil's proprietary.
UV Filter Quality
The filter must have maximum transmittance in the 250-280 nm (UVc) range while blocking absolutely any sun radiation from outside this transmission band.
Ofil's top quality filters absorb and prevent sun radiation from reaching the UV detector. As a result, background "noise" of solar radiation is diminished and the DayCor camera can operate at very high gains in full daylight.
Image intensifier
The quality of the UV image intensifier that creates the bright UV image from the very faint UV emission source must be very high.
Ofil uses the most sensitive image intensifier for the UVc available. Hence DayCorŽ detects a discharge of 1.5 pC from a distance of 8m at normal video rate (25 or 30 frames/sec) without any image processing.
