1999 ESO CCD Workshop / Mosaic flatness? / New team member

[James Beletic]

Posted to CCD-world:
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                                15 November 1998

Hello CCD World,

   I write about 3 things.

1999 ESO CCD Workshop - August or September?
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   ESO has approved the funding for another CCD Workshop.  We need to set
   a date as soon as possible to reserve hotel rooms, auditorium, etc. and
   to enable participants to schedule their lives and arrange inexpensive
   flights.  Our main scheduling issue is whether to hold the workshop in
   August or September of 1999.

   Good reasons for the week of August 16-20 are: (a) it is one week after
   the 11 August total solar eclipse (centered on Garching!) and August is
   easier for family vacations of North American participants.  However,
   August is in general not a good time for European participants.  (If we
   go into September, is there any preference for late September and an
   overlap with the cultural phenomenom known as Oktoberfest?)

   Please send an E-mail back to me if you have a preference for date
   and also to let me know if you think you will attend.  I will post
   CCD world in a few weeks with the result of this "vote".  In any case,
   please reserve time in your busy schedules for a get together next year.
   Over the next few months, I will work with all of you to define the
   format of the meeting.  (One pledge from us - the proceedings will
   come out MUCH faster from this workshop!)

Questions about mosaic flatness
-------------------------------

   At ESO, we are now seriously getting into the business of CCD mosaics.
   Next month, we will have first light on an 8k x 8k made of 8 EEV 2k x 4k,
   15 micron devices (with a 9th 2k x 4k chip on the side for guiding).
   We have also put together a mosaic of one 2k x 4k EEV and one 2k x 4k
   MIT/LL for a spectrograph (the EEV chip at the blue end of the mosaic,
   the MIT/LL at the red end - to maximize q.e.).

   Our experience is as follows: Putting 8 EEV CCDs down on a "flat" table
   that holds the CCDs gave us 36 microns peak-to-valley, 7 microns rms
   from the best fit plane (which means that most of the mosaic is very
   flat with a few areas at the peak and valley locations).  This was
   without any adjustment - we just "plopped" the CCDs into place.  As this
   was within the specification we did not try to improve the flatness.

   We needed to work much harder to get one EEV and one MIT/LL CCD to be
   aligned in the vertical direction.  The MIT/LL package is much thinner
   so we made an adapter plate that makes the bottom of the two CCDs look
   identical.  We use shims on the MIT/LL adapter package to adjust the
   height and tilt of that CCD.  After several iterations, the two CCDs
   now have a peak-to-valley of 18 microns, well within the specification
   of 50 microns and better than the goal of 20 microns peak-to-valley.

   In order to measure these mosaics, we did not copy any of the existing
   systems at RGO, Copenhagen or Lick (that would be too easy), but instead
   are developing a system based on a commercial laser diode triangulation
   sensor.  (We are building the system so that it can measure mosaics that
   are up to 16k x 16k in size, both "bare" or through the window - i.e.
   warm or cold.)  A paper on this system (and demonstration, hopefully)
   will be presented at the ESO CCD workshop.

   My questions to the community are:  Would others making mosaics please
   let us know what kind of success you are having with the flatness of your
   mosaics?  What are your requirements (from the instruments)?  What
   peak-to-valley and rms do you achieve?  And how are you measuring?

New member of ESO's Optical Detector Team
-----------------------------------------

   I am pleased to announce that ESO has successfully concluded its search
   for a "CCD Detector Specialist".   We were fortunate to have
   several good candidates and we have chosen Cyril Cavadore.  Cyril is a
   Frenchman who recently completed a Ph.D. in electrical engineering,
   during which he designed CMOS sensors at Thomson.

   An avid amateur astronomer, Cyril has designed and built his own
   telescope, has designed and put together several CCD systems
   (up to 2k x 2k), has developed telescope control / image processing
   software that is sold commercially and, with colleagues, he conducts
   an automated asteroid search program (19 found so far).

   The 19 asteroids are presently unnamed, since an asteroid must complete
   one orbit around the Sun before it can be named by the discoverer.
   So be nice to Cyril when you meet him...............:)

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I hope life goes well for everyone out there in CCDland.

                                All the best,

                                   Jim


=========================================================================
    James W. Beletic                         E-mail:  jbeletic at eso.org
    European Southern Observatory            Phone:   +49-89-320-06520
    Karl-Sch-Str 2, D-85748 Garching, GER    FAX:     +49-89-320-2362
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