info and idea request for PI CCDs

[Paul Jorden]

Greetings  Qian Song & all,
>      I bought a LN/CCD 1752PB from Princeton Instruments which is a thinned, 
> back illuminated and pixel size 15um, 1752X532 spectrometric detector. I don't
> know why its full well capacity is only 5900 e and readout noise 8.6 e. PI 
> response me it's the correct CCD. I am curioused if anyone got a better one 
> from PI for the ad. I saw before I bought says the FWC not less than 260,000 e
> and readout noise 4-6 e (only it's an ad. titled with 'preliminary').
>
This may not be very helpful, but it seems to me you should complain or return 
the detector to PI. The electronics may not be set up properly with the CCD. If 
it is an MPP chip the full well would be less than 260K but more than 6K! Try 
contacting John Geary (John any comments?)- he has tested these chips, and 
reported results at the recent ICSOI conference at Grand Cayman.

>      I got trouble too when I use LN/CCD 1024TKB also from PI. When
> it works under -100C, water vapor comes up on the quartz window ahead of CCD 
> chip and behind of the shutter (the vacuum condition of the space between the 
> chip and the window is good) as the exposure time reaches several tens of 
> seconds (the enviomental humidity about 60% and temperature 10C to 15C). The 
> lower the working temperature, the quiker vapor comes up. when I uninstalled 
> the shutter (there's another quartz window in front of shutter) with the outer 
> window together, the vapor no longer came. I cannot do without the shutter in 
> my future work. So, I need your help if you can give some ideas to solve this
> problem.
>
This sounds like 'normal' dewar window condensation. The cold detector can cause 
radiative (& maybe some conductive) cooling of the window. The usual tricks are 
to install some heater wire or resistors in a ring around the window or to blow 
dry air across its surface.

Good Luck, Paul Jorden

[2nd copy of msg? 1st one on 23 dec failed?]
-------------------------------------------------------------------
E-mail:  prj at ast.cam.ac.uk         Machine: Kria.ast.cam.ac.uk
Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 0EZ, UK.
Phone: +44 (0) 1223- 374000  \direct phone- 374811 \RGO Fax- 374700