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