How much white light leakage is there?
This is a common question because there is a specification for allowable visible light leakage from ultraviolet lights. This question doesn’t really make sense for the BlueLine lights because ALL of the light coming out is visible, blue light. The true issue, though, is not how much visible light is reaching the surface, but how much visible light that is not coming from the indication reaches the eye of the inspector. It’s about viewing contrast. If an ultraviolet light leaks too much visible light then both the fluorescence AND the visible light leakage will reach the eye, and the leakage reduces the contrast of the fluorescence. In the case of the BlueLine blue lights, the yellow filter glasses prevent the intense blue light that reaches the inspection surface from reaching the inspector’s eye to reduce contrast, while still efficiently passing the wavelengths of the fluorescence emission. The result is that indication are seen in high contrast, without interference from the visible
