====== 2012-09-06 Notes from Steve ======
  Hi,
  
  I see that one of John's slides asks if the Cilas DM is elliptical.  Yes.
  
  Here is the longer answer:
  
  The are indeed.  The pupil is of course 125x177mm.  Since the DM band outside the pupil controls tilt and edge modes, Cilas recommends that we use a blank diameter of at least 250 mm (which is less than the standard ratio since we have independent tilt control).  However, if we went with a diameter more like 265 mm, we would have the option of doing all the tilt correction at the DM - no additional cost for the increase from 250 to 265.)
  
  Here is the ROM for this size range (now exactly 1 year old):
  
  
  > > For these dimensions, due to additional work explained above there is a price increase:
  > > Mirrors without driver:
  > > 6 MONO31: about 347 k€. For one spare MONO31: about 43 k€
  > > 6 MONO63: about 383 k€. For one spare MONO63: about 48 k€
  > > Mirrors with drivers:
  > > 6 MONO31 system: about 427 k€. For one spare MONO31 system: about 53 k€
  > > 6 MONO63 system: about 483 k€. For one spare MONO63 system: about 62 k€
  > > These prices are still ok for larger blanks (for instance up to 220 mm x 330 mm if needed).
  > > 
  > > The main mechanical resonance should be in the 700 Hz range (rough estimate) for an elliptical blank dimension around 175 mm x 250 mm.
  > > 
  > > DM mounting could be elliptical around 260 mm x 340 mm, 100 mm depth.
  
  Note the large size of the unit, will have implications for the AO package dimensions.  
  
  This currently corresponds to only $686K for the most expensive option - obviously a bargain, we should grab it before the exchange rate turns around!
  
  Steve