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re: a 12' non-cube
12 mar 2001
chuck simmons wrote:
>> >one thing to consider is that you are planning to use a section of a
>> >right parabolic "cylinder" highly off axis. the parabolic shape does
>> >not work well off axis.
it seems to "work" fine, energy-wise, as far as i can tell, vs "working"
as in making an image. in other words, all of the incoming rays end up
on the target, but they may be scrambled compared to the luminous object
that made them. i think roland winston discovered this in 1966.
>you can do a simple graphical ray trace... you can find perpendiculars
>to the surface by drawing lines from the focus to the surface and then
>drawing lines parallel to the axis. bisecting the angles where the lines
>parallel to the axis meet the lines from the focus at the surface gives
>perpendiculars to the serface... to trace the rays... draw parallel lines
>from the source direction to the surface at each perpendicular you found.
>measure the angle and draw a line on the other side of the perpendicular
>at the same angle. this is the reflected ray... you probably need only
>trace four rays.
thanks for the further thoughts. i tried this with a dozen rays graphically,
and with a few numerical examples. every ray hit the target. this was kind
of exhausting after a while. ergo, we have proof by exhaustion.
nick
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