CCD-world: PTC FUNNIES

CMOSCCD at aol.com CMOSCCD at aol.com
Tue Apr 3 15:02:18 CLT 2012


****************
 
Hi Bob and Gang,
 
PTC funnies surface when . . .
 
1). When CTE isn't behaving which smooth's out the shot noise  measurement. 
 The CTE problem has to be pretty bad though for it to  influence e-/DN.  
Why use the sensor in the first place ?   
 
2). When V/e- nonlinearity is present (e.g., CMOS).    However,  one 
additional step to the standard PTC approach makes  the technique viable.   Here 
you will interestingly find that PTC  will need to keep track of two gain 
terms.  i.e.,  SIGNAL (e-/DN) and  NOISE (e-/DN).   For they are different as 
signal varies.
 
3). When the incoming wavelength is < 4000 A.   Short  wavelengths produce 
multiple electron hole pairs (i.e., quantum  yield).   PTC reacts with a 
e-/DN gain shift (decreases with  decreasing wavelength).
 
4). Software engineers.  :-)    
 
Jim
 
ps .. PTC is also an excellent way to measure linearity. . .  (e.g.,  see 
below)
 

 

 
**********
 
 
 
 
 
 
In a message dated 4/2/2012 3:58:48 P.M. Pacific Standard Time,  
stern at lmsal.com writes:

The SPIE  paper below describes our experience with characterizing devices 
for the GOES  SXI instrument. Note that we used a combination of methods: 
Fe55, multiple  frame photon transfers, and the two-frame "ramp" technique 
(which I think  first appeared in a Walton et al. 1984 SPIE paper: see the 
reference list of  the SXI CCD paper). As can be seen in Fig. 7 of our paper, 
the three  measurements agreed quite well ( < 5%); however, there are often 
pitfalls  in the setup or analysis, as mentioned in the CCD-World discussions. 
And you  should always rely on Jim for the definitive answer (in his book)! 
 




good luck!


Bob Stern


_http://spiedigitallibrary.org/proceedings/resource/2/psisdg/5171/1/77_1?isA
uthorized=no_ 
(http://spiedigitallibrary.org/proceedings/resource/2/psisdg/5171/1/77_1?isAuthorized=no) 




 
 
------------------------------------------------------
Robert Stern  Lockheed  Martin
Solar and Astrophysics Lab  A021S/Bldg. 252 
3251 Hanover Street  Phone:  (650) 424-3272
Palo Alto CA 94304  Fax:  (650) 424-3994







--  
This message has been scanned for viruses and 
dangerous content by _MailScanner_ (http://www.mailscanner.info/) , and is  
believed to be clean. 


-- CCD-world --
CCD-world is fully  moderated.  Send posts to CCD-world at ctio.noao.edu
Standard replies  will go to the list; address personal replies manually.
For more  information, please go to:  
http://www.ctio.noao.edu/mailman/listinfo/ccd-world


-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20120403/a5c549ad/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Untitled.jpg
Type: image/jpeg
Size: 154918 bytes
Desc: not available
URL: <http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20120403/a5c549ad/attachment-0002.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Untitled.jpg
Type: image/jpeg
Size: 69016 bytes
Desc: not available
URL: <http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20120403/a5c549ad/attachment-0003.jpg>


More information about the CCD-world mailing list