Wavelength dependant reflection ghosts

Bit of a long shot but in your image of the SBIG camera if I zoom in really close I can see what looks like a CCD shipping protective foil still in place over the cover glass, it doesn't cover the full sensor package but I can see the curved edges of the foil just outside the main active region, most apparent on the left side?

It might just be the way the CCD chip is assembled in the particular package that SBIG are using, or just an artefact in your image but I can say it is not there on my QSI 683 which uses the KAF 8300 detector.

I have no experience of handling KAF ccd's but the OnSemi and Sony detectors I used to work with were shipped with transparent foils over the cover glass that we removed after mounting in the chip socket. Some of the foils were opaque and really obvious but on more than one occassion the foils were crystal clear and easy to miss during assembly.

William.

 

Doug.

I beg to differ here, I had been working with OnSemi products for a number of years as an imaging engineer and OnSemi DO fit protective foils over SOME of their CCD devices, I include an extract from OnSemi's own handling instructions and you may find their complete guide to handling publication here (see page 5) :

http://www.onsemi.com/pub_link/Collateral/AN52561-D.PDF

It may be that the CCDs supplied in some production trays do not include a protective foil but the CCD's supplied in field replacement kits that I used to handle all came with foil attached. It is not beyond the bounds of possibilities that they may have supplied SBIG a tray of CCD's containing sensors with foils attached?

I retired a few years back and perhaps things have changed.

William.

 

Posted sectional and annotated view of Christopher's sensor image where I have added arrows pointing to what looks very much like the edge of a sensor protective foil.

William.

 

It had caught out a few of my field colleagues Colin. I have a medical engineers alert bulletin from a few years back advising us to check the foil is removed from certain OnSemi detectors after we replace them in our X-ray cameras, the foil is so transparent that you do not notice it unless looking really really hard with a magnifying glass (well that's the case for some of us over a certain age!) and you do not see much reduction in image resolution when carry out the QA after, but you do see "ghost" reflections back from the image intensifier prime optic as the foil is very reflective.

I was lucky that all my systems contained Sony detectors and the handling foil on those is opaque, I seem to remember some French sourced detectors as well that had a blue coloured foil but I can't recall the make.

William.

 

F814020088

 

my bad, I gave you the number off of the Filter Wheel, I will send the correct number later today

 

The correct serial number is 83F011684, btw if you look at the ON data sheet for the KAF-8300, there is no structure in the mechanical assembly diagram that matches the position of the suspected protective cover film -

 

It will be interesting to see the outcome Christopher.

I dug out some of my old factory CCD notes this afternoon, they are a few years old now and possibly out of date, still labelled as "Kodak" rather than OnSemi, but I see eight versions of the KAF 8300 listed and only two are supplied with the cover film as standard but interestingly both of these are the the non-AR coated cover glass versions (plain glass) KAF-8300-AXC-CP-AA (standard grade with micro lens) and KAF-8300-AXC-CP-AE (engineering grade with micro lens).

I won't post again, I think I have unintentionally upset Tim and Doug :-(

William.

 

The ON application note cites that the Protective Film is an option as well but even if the option was not checked it could be that the distributor (or ON) had existing parts already on hand with the option that were shipped to meet a delivery date. I've gotten substituted parts before from Intel and others back when I was in the electronics manufacturing business. It could also be that the film is on the window that SBIG puts on top of the camera CCD - possible ???

 

I know I said I wasn't going to muddy the waters any more, but you know how it is when dog gets a bone!

Have you noticed anything else a bit strange in the image? It looks as though the camera chamber cover glass has been dislodged, there is a gap on the left side of the opening where the edge of the chamber window glass is visible, I have applied a little curve to the image to bring it more clearly into view. Doesn't look normal to me. Seems the only way to determine exactly what is wrong is for the camera to be inspected professionally.