by DonJones » Thu Nov 12, 2009 5:20 am
I spent over an hour looking at the first several pages of this thread. It seemed oddly familiar somehow. Then I went to bed and saw the double reflection of the red radio tower light some quarter mile from my relatively new double glazed window. I believe the window was manufactured somewhere near sea level and shipped to Los Alamos at 6 to 7 thousand feet and has somewhat of a bow in both panes of glass, the outer one bows out, the inner one in. I can see the reflection on the left or the right of the direct image, depending on which side of the window I view it. I tried pencil and paper ray-tracing the results and got nowhere until I realized that the image and the reflections were not the result of a transmission and a reflection of the same ray. Assume that the rays from both images converge at the eye (obviously true since the eye/camera is seeing both rays coming from different points) and trace the rays backward. The result is two parallel (effectively so) rays leaving/impacting the glass at different points. Thinking time forward again it is the non-parallel glass that deflects two separate rays so that the reflected ray of one converges with the direct, non-reflected path of another at the eye. Move the eye to a different point, and it sees two different rays that react differently.
I have probably missed something – perhaps that someone else has suggested the same thing and been shown to be wrong in the many pages that I skipped, if so, my apologies.
I spent over an hour looking at the first several pages of this thread. It seemed oddly familiar somehow. Then I went to bed and saw the double reflection of the red radio tower light some quarter mile from my relatively new double glazed window. I believe the window was manufactured somewhere near sea level and shipped to Los Alamos at 6 to 7 thousand feet and has somewhat of a bow in both panes of glass, the outer one bows out, the inner one in. I can see the reflection on the left or the right of the direct image, depending on which side of the window I view it. I tried pencil and paper ray-tracing the results and got nowhere until I realized that the image and the reflections were not the result of a transmission and a reflection of the same ray. Assume that the rays from both images converge at the eye (obviously true since the eye/camera is seeing both rays coming from different points) and trace the rays backward. The result is two parallel (effectively so) rays leaving/impacting the glass at different points. Thinking time forward again it is the non-parallel glass that deflects two separate rays so that the reflected ray of one converges with the direct, non-reflected path of another at the eye. Move the eye to a different point, and it sees two different rays that react differently.
I have probably missed something – perhaps that someone else has suggested the same thing and been shown to be wrong in the many pages that I skipped, if so, my apologies.