On 23/06/2011 13:15, Yigit Turgut wrote: > Intensity of light is reduced by inversely proportional to > square of the distance. not true with a laser. That would imply the spot doubles in diameter=20 with double distance. many don't --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .