firstly hello to all, i'm new here and i'd like to ask admins to forgive me if i posted this thread in a wrong place - i could not find Optics section. i need a fresnel collimated UV light with adjustable focus. don't trust the ordinary lens because of optical aberration. one with a diameter of at least 15 centimeters (~ 6 inches) searched everything, these handheld UV flashlights are tiny, professional studio light are not with the UV and do not have adjustable focus(and are really expensive). tried to search a desk lamp with adjustable focus, thought i'd put some tiny CFL bulb there and use a focuser to make rays parallel. but looks like nobody produces desk lamps with zoom capability. large scale Reducers strike 2500-5000$ price. my pocket won't do that. searched by google "Optical Collimator", "Focuser" and nothing... or only professional tools came up, with horrible prices. i do understand that the field of Optics is not commercialized thus there are no general use household objects that use zoomable lenses or collimators. and that is why only way to get such a collimator is to buy some specialized expensive device. but i still do not give up hopes that there is some affordable collimator out there that will do a basic thing, receive a UV out of a tiny LED,(or CFL Bulb) and output a non aberrated paralellized stream with adjustable focus. any suggestions where should i search one?