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    Re: Floating mirror
    From: Wolfgang Hasper
    Date: 2015 Apr 21, 18:04 +0200
    Hi all,
    I considered using water soluble tungsten compound
    http://www.heavy-liquid.com/en/productinformation/tableofdensities/
     
    and have a glass-substrate first surface mirror float directly on this liquid.
     
    Assuming the glass carrier is homgenous in density (which I think is justified) this could yield good results.
     
    As yet no idea how expensive that would be.
     
    Regards
    Wolfgang
     
     
    Gesendet: Dienstag, 21. April 2015 um 01:41 Uhr
    Von: "Brad Morris" <NoReply_Morris@fer3.com>
    An: wolfgang.hasper@web.de
    Betreff: [NavList] Re: Floating mirror

    Absolutely agreed Alex.  My original estimate was 4 rotations and observations.

    For the purposes of illustration, I suggested just 2, making the averaging easier to see. 

    My initial assessment was that the floating mirror was a bad approach.  So called 'common knowledge'.  But once Greg pointed out the averaging trick (his point 4), it became obvious that 'common knowledge' was wrong (me included!)

    Brad

    On Apr 20, 2015 6:52 PM, "Alexandre Eremenko" <NoReply_Eremenko@fer3.com> wrote:

     

    Brad,
    You wrote:
    
    >Assume the mirror has a pitch forward of 5 deg, but only in that angle, side
    >to side is perfect.
    
    I'm afraid you cannot assume that "side to side is perfect".
    Thus I think you need 4 rotations to average:-)
    
    Alex.
    
    

     

       
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