Uranus and Neptune

Ok, tried looking this up before asking. Why don't lenses and mirrors effect angular spreading? They obviously do in short distances, ie the ants I fried as a kid on my drive way, or the parabolic troughs used for solar power generation in the SW U.S.

So why wouldn't it work, to at least some degree, for longer distances? I can see if there is some loss or an inability to 'perfectly' align the rays to be absolutely parallel. But we don't need perfect, hell if our target is an entire moon or planet and its within the solar system...? I'm sure I'm missing something, its been awhile since I took college physics.
Brooks

--- In spacesettlers@yahoogroups.com, Ian Woollard wrote: