ATM Invisible spider vanes....

["Anderson, Jay" <andeja@mail.va.gov>]

Just wondering if anyone has experimented with a window to suspend the
secondary holder on a Newt?  I have read some things that indicate that
optical glass must be used and its surface must me near perfect.  What
about 3/8" or 1/2" plexiglass?  It is 10X clearer than optical glass (I
understand).  Maybe I am missing something but seems to me that having a
window will remove all vane obstuction and diffraction caused by the
vanes and so improve image contrast.  Also, the telescope tube could be
a closed unit and so not suseptible to thermals, dust on optics, dew,
etc.  Geeze, you could even pump out the air and fill the tube with
Nitrogen or something.  Just a thought.