CCD-world: Re:

[Peter Conroy]

The following was posted to CCD-world:

Dear CCD World

>Peter Conroys' recently mentioned water damage to AR coatings on SITe 
>ccds (in the context of cleaning ccds). This prompts me to ask the 
>community if a particular problem we have with a Tek1024 could be 
>attributed to the same cause, i.e. permanent damage by water.
>
>We recently found that one Tek1024 device (of 6 we have) exhibits many
>small multi pixel spot like patches of up to 10% attenuation. This is
>apparent only in U_band flats. The surface of the device looks normal to
>the eye and by baking the device in situ at 40 deg. C these spots
>disappear for a up to a week but then slowly return. 

Our site staff once tried to blow the dust off  a thinned SITe with a dry
air  gun. The gun contained water condensate and blew several drops about
3mm in diameter onto the surface of the chip. Even with vacuum baking these
spots always showed lower response to flats at almost any  wavelength, the
effect was permanent. These spots could just be see by eye at low incidence. 

>I don't know how good plasticizers dissolve in Pet Spirit, but if it is
>anything like alcohol, acetone, etc., I would be a very reluctant using it
>from a plastic squeeze bottle after our bad experience with plasticizers -
>see   http://www.saao.ac.za/news/news32/node16.html

I had not thought of this. I was fairly desperate to clean the oil
contaminated chip. I wonder if it would be possible to use an all glass
wash bottle pressurised by a squeeze bulb.

Regards
--------------------------------------------------------------------
Peter Conroy - Senior Draftsman - Design Office
Mt Stromlo Observatory -  Canberra Australia
Private Bag  Weston Creek PO ACT 2611 Australia
Email - conroy at mso.anu.edu.au
Phone - 61 02 6279 8022   Fax - 61 02  6249 0233 
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