CCD pixel-to-pixel variations

[Ken Smith]

Posted to CCD-world:
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Dr Smartt:

I have actual test data from EEV on PRNU (photoresponse non-uniformity) vs
wavelength for the CCD-26, which is a 1353x286 frame transfer spectroscopic CCD,
thinned, MPP (IMO) mode.  They used a monochronometer I believe.  So here goes:

Wavelength (nm)    PRNU (%)

250                7.2
270                7.4
300                7.2
350                2.5
400                1.4
450                1.2
500                1.0
550                1.0
600                0.97
675                0.95
755                2.4
765                2.8
775                3.4
925                16.3
940                18.1
955                20.0

I don't have actual image data at each wavelength from which the above numbers were
determined, so I don't know how PRNU varies spatially, other than I suspect it
changes slowly over the CCD due to different thinkness of the wafer etc.

As far as long term variation in PRNU is concerned, I am looking for that sort of
data myself.  I suspect data is available, but not in any convenient summary form,
but just massive raw flat field calibration archives.  The Hubble Space Telescope
web site may have a lot of such data on line, but the CCD is subject to space
radiation effects.  You also have to be careful in making sure in what conditions
was the CCD kept in interpreting the data.  Was it always in vacuum, N2, in and out
of a cooler, handling, does it have a UV coating or other surface treatments, UV
flash, etc ?  Otherwise you will have an apples and oranges situation.  I believe
the EEV CCD you are talking about is thinned and any treatments/coatings would be
fairly stable.


Ken Smith
Routes Inc
Ottawa, ON
Canada


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