====== Visible Coatings ======
  Subject:
  Re: Meeting Notes -> Visible coatings
  From:
  Michael Ireland <michael.ireland@mq.edu.au>
  Date:
  Tue, 24 Jul 2012 18:04:19 +1000
  To:
  Denis Mourard <denis.mourard@oca.eu>
  CC:
  Stephen Ridgway <ridgway@noao.edu>, "charaao@chara-array.org" <charaao@chara-array.org>
  
  ... or as I said earlier, even better is >90% transmission in the
  infrared. This is easy to do with coatings that I could get done in
  Sydney for <$1000, e.g. the single-layer I mentioned.
  
  On 24 July 2012 18:02, Denis Mourard <denis.mourard@oca.eu> wrote:
  > > Steve,
  > > if we want to keep the excellent VIS/IR collaboration on the instrument side
  > > we should certainly have this kind of splitting indeed.
  > > We can discuss that during the telecon.
  > > Denis
  > > Le 23/07/2012 21:11, Stephen Ridgway a écrit :
  > >
  >> >> Hi Denis,
  >> >>
  >> >> Would this be panchromatic and also have 20/80 in the infrared?
  >> >>
  >> >> Steve
  >> >>
  >> >>
  >> >> On Jun 28, 2012, at 5:03 AM, Denis Mourard wrote:
  >> >>
  >>> >>> Hi,
  >>> >>>
  >>> >>> we have had a short discussion this morning about the specs for the
  >>> >>> coating of the beamsplitters. Our starting point is that 100% of visible for
  >>> >>> the WFS corresponds to a limiting magnitude of V=12.
  >>> >>> Thus an uncoated entrance side beamsplitter (with AR on the back side)
  >>> >>> will reflect 4% to the WFS and thus corresponds to a limiting magnitude of
  >>> >>> V=8.5.
  >>> >>> This limit is in agreement with the current limitations of PAVO and VEGA
  >>> >>> but will limit the performances if the full AO is in operation, i.e. with
  >>> >>> the deformable mirrors. The strehl improvement will permit to reach fainter
  >>> >>> magnitudes for the science in the visible and in that case we think that a
  >>> >>> beamsplitter 20/80 (20 for the WFS) would be a good choice. We have
  >>> >>> considered the possibility of sending 100% of the blue wavelengths (<600nm)
  >>> >>> but, from old exchanges we have had on this list,  it doesn't seem to be a
  >>> >>> good idea with respect to the refraction or chromatic effects.
  >>> >>>
  >>> >>> Any comments?
  >>> >>>
  >>> >>> Denis, PhilippeB, Nicolas, Karine.
  >>> >>>
  >>> >>> Le 23/06/2012 01:15, Theo ten Brummelaar a écrit :
  >>>> >>>>
  >>>> >>>> Dudes,
  >>>> >>>>
  >>>> >>>> HEre are my notes from last week's meeting. All the pictures are
  >>>> >>>> uploaded to the wiki:
  >>>> >>>>
  >>>> >>>> http://chara-ao.wikispaces.com
  >>>> >>>>
  >>>> >>>> Comments welcome. I'm thinking it's time to start putting the meeting
  >>>> >>>> notes on the wiki as well. I mean, do we care if a random person reads them?
  >>>> >>>> Alternatively we could pay the $60 a year to keep them private. I will
  >>>> >>>> investigate this on my return from the SPIE. See you there!
  >>>> >>>>
  >>>> >>>>     Theo
  >>>> >>>>
  >>> >>>
  >> >>
  >> >>
  > >
  
  
  
  -- MICHAEL IRELAND | Lecturer in Astrophotonics Department of Physics and Astronomy, Macquarie University Instrument Science Group, Australian Astronomical Observatory W +61 2 9850 8901 M +61 424 228 579 F +61 2 9850 8115