Jim Tallman contributed: >Perhaps I was a bit too general in my last posting, because I can see >problems if the protective acrylic window was bowed and not perfectly flat. >Looking at some of the replacement windows in my garage door, the acrylic >ones are not as flat as the glass ones, and I would assume that the rays are >shifted as a result. Actually there are optical imperfections in automotive >glass too, if you really think about it.
There may also be a problem with double glazed windows which in the UK are sealed and filled with inert gas. These act like aneroid barometer capsules and bow in or out with the local atmospheric pressure. The distortion can be seen when viewing straight lines reflected by the glass surface. Tony Moss -
