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Thread: Optimizing an off-axis reflector system?

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    Default Re: Optimizing an off-axis reflector system?



    "Overhead projectors" did something similar, they were standard tools in baby boom classrooms everywhere. Powerful light would be delivered from below through a transparency, projecting the transparency detail onto a screen for the class to see. I suppose you could use reflected light from the primary opaque object, but there would need to be some way to amplify brightness to overcome the dilution of photons with magnification. I believe the common design used a flat secondary mirror with magnifying optics, so you could adjust the size of the projected image within limits. A second screw was used to focus. If the projector screen was not at 90 deg to the image, the top or side was wider comparing one edge to the other. So, the optical axis had to be centered. If you don't need to magnify then you don't need to focus, and the system is as simple as a flat mirror pointing photons at a flat screen.
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    Default Re: Optimizing an off-axis reflector system?

    The optical system of an OHP was simply a converging lens element. A photocopier uses a similar system, as does a camera. I think the OP is looking for a mirror-only solution.

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    Default Re: Optimizing an off-axis reflector system?

    I thought the problem was about finding software for the design of a mirror shape that can focus reflected rays into any given plane. Some projectors have interesting focus properties but I don't think the OP is looking for that. Maybe he went somewhere else to find a solution, it has been a while.
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    Default Re: Optimizing an off-axis reflector system?

    As a viewer of OHPs in the 60s and 70s the aberrations were unpleasantly large. Making something like this work well is not easy and is a task best left to real experts in that specific technology.
    j.gardavsky likes this.

 

 
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