[ATM] RE: Primary Mirror Retainers

[tkrajci at san.osd.mil (Tom Krajci)]

>From: "Stuart Hutchins" <stuart452@earthlink.net>

>Has Tony Owens' "compliant focuser" actually been built and tested?  

To my knowledge, no.  But look at Don Clement's compliant focuser for a
similar approach.  And I think Don has used it as the focuser on some
SCT's, such as a Celestron 14...if I remember correctly.

>In
>reviewing the drawing posted on your website, I'm not seeing a
mechanism
>that ensures pure axial motion of the mirror.  

The 'mechanism' is the two compliant (stretching, flexing)
drums/plates/sheets.  It resists bending moments pretty well, yet allows
piston motion for mirror focusing.

>The actuator operates off
>center, and the compliant disks will tilt somewhat at their hubs.

This actuator is closer to on-center than Meade and Celestron.

Show me a focuser design of this type (central perforation in mirror)
that has an on-center actuator.  (Honestly, if you can improve it...tell
me how.)

>If a sliding sleeve enforces axial motion, then the fit must be a
fraction
>of a wavelength to maintain arc-second pointing.  What am I missing?

Sleeve not needed...the compliant steel sheets constrain the motion.

I hope this helps.

Tom Krajci
Tashkent, Uzbekistan


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