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Thread: Liquid Mirror Zenith Telescope

  1. #1 Liquid Mirror Zenith Telescope 
    Time Lord
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    Apr 2008
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    This is more an engineering question, but I know some folks here build their own, or have an interest.

    I see room for improvement in this first generation of liquid mirror telescopes. In everything beneath the dish top.

    The mount is inelegant. It attempts to solve the problem of vibration and dish distortion with rigid materials machined to tight tolerence. Brute force, and money. Isn't that ironic after inventing a mirror that is just the opposite?

    My suggested solution has the dish also floating, in a larger cylindrical pool of water. The entire dish would be supported by water, and probably of cheap ferrocement construction, with a ballast at the bottom. By spinning the water, the dish spins. The mass (not motor control) helps to maintain consistent rotation. Very fine streams of water (think garden irrigation) provide enough pressure to keep the dish centered in the pool. Build the pool large enough that turbulence from imperfect sides does not occilate the dish.

    With reinforced concrete construction, a dish the size of stadium roof is feasable and would cost less to build than the stadium, because stresses on it are minor. We can excavate for much of the pool depth, to save on costs. Hire local concrete contractor, wherever the site.

    That's going to be a lot cheaper at any scale than our current LMTs. Is it otherwise better? Does the water decouple Earth tremors well enough or does it need some kind of pad? Problems?


    A pong by any other name is still a pong. -williampinn
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  3. #2 Re: Liquid Mirror Zenith Telescope 
    Forum Professor Wild Cobra's Avatar
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    Quote Originally Posted by Pong
    This is more an engineering question, but I know some folks here build their own, or have an interest.

    I see room for improvement in this first generation of liquid mirror telescopes. In everything beneath the dish top.

    The mount is inelegant. It attempts to solve the problem of vibration and dish distortion with rigid materials machined to tight tolerence. Brute force, and money. Isn't that ironic after inventing a mirror that is just the opposite?

    My suggested solution has the dish also floating, in a larger cylindrical pool of water. The entire dish would be supported by water, and probably of cheap ferrocement construction, with a ballast at the bottom. By spinning the water, the dish spins. The mass (not motor control) helps to maintain consistent rotation. Very fine streams of water (think garden irrigation) provide enough pressure to keep the dish centered in the pool. Build the pool large enough that turbulence from imperfect sides does not occilate the dish.

    With reinforced concrete construction, a dish the size of stadium roof is feasable and would cost less to build than the stadium, because stresses on it are minor. We can excavate for much of the pool depth, to save on costs. Hire local concrete contractor, wherever the site.

    That's going to be a lot cheaper at any scale than our current LMTs. Is it otherwise better? Does the water decouple Earth tremors well enough or does it need some kind of pad? Problems?
    Problems I see:

    First of all, the only direction the mirror could see would be strait up. It wouldn't be steerable. Then on top of that, it would lose accurate from the tidal effects of the moon.


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  4. #3  
    Time Lord
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    Yeah, liquid mirror telescopes often have "zenith" in the name. It's an acceptible limitation when we only wish to see insanely far, wherever.

    I guess for stadium sized LMTs the tide would be a drag. Would that degrade the image or just distort it? The latter can be fixed.
    A pong by any other name is still a pong. -williampinn
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