Re: Dynamic range of a CCD

Posted by James Pawley on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Dynamic-range-of-a-CCD-tp593278p593281.html

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Hi everybody,

 

I don't understand why the dynamic range of a CCD is defined as the full-well capacity divided by the camera noise, and not minus the camera noise.

 

Thanks a lot for your help,

 

Laurent.

 

___________________________________________

Laurent Gelman, PhD

Friedrich Miescher Institut

Facility for Advanced Imaging and Microscopy

WRO 1066.2.16

Maulbeerstrasse 66

CH-4058 Basel

Tel.: [phone] / Cell phone: [phone]

www.fmi.ch

 

 

Dear Laurent.

Actually it is a misleading way to define dynamic range.  The idea is that the read noise gives you the error in the intensity of any measurement. So this definition of dynamic range implies that it is a measure of the number of separable intensity levels that might be visible in the data.

The problem is that, once the signal level exceeds the square of the read noise (in electron/pixel) the ability of discriminate different signal levels becomes limited  more by Poisson Noise than by the "dynamic range".

So, in sum, it is just a convention that works pretty well to separate better CCDs from worse.

For microscopists however, the read noise is a more useful measure because we seldom have specimens bright enough to produce a "full-well" signal.

Jim P.

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Jim Pawley (Summer address) c/o Postmaster, Egmont, BC, Canada, V0N-1N0 604-883-2095, [hidden email]