Author Topic: sensor Signal−to−Noise Ratio  (Read 1644 times)

Stephan

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sensor Signal−to−Noise Ratio
« on: April 24, 2018, 06:18:13 PM »
Hi all

I was wondering whether someone ever characterized the noise of the sensor used on the miniscope, for example by measuring the Photon Transfer Curve (https://www.adimec.com/how-to-measure-the-photon-transfer-curve-for-ccd-or-cmos-cameras/).

Plotting the log of the  Standard Deviation versus the log of the average effective signal , one would expect to see a region where the photon shot noise is dominant, and the slope of the curve is equal to 0.5.

I measured this curve and identified a portion of the curve where the slope is 0.5 (STD~(MEAN)^(0.5)). This was roughly between the values 1 and 50 (at gain 4x). But to my surprise there is also another portion (much larger) which has a very different regime. In this portion, extending from the values 50 to ~200, I see the STD varying linearly with the MEAN.
Finally the curve ends as expected (values 200-255): the STD drops to zero as the pixels saturate.

I do not understand the linear relationship between STD and MEAN at the intermediate light levels.
Did anyone ever made this measurement? Did you observe the same thing?

Thanks for your help,
Stephan

Daniel Aharoni

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Re: sensor Signal−to−Noise Ratio
« Reply #1 on: April 26, 2018, 04:25:04 PM »
Hi Stephan,
Thanks for posting this information. We have never measured the Photon Transfer Curve ourselves but I will try to get around to doing so soon. Can you upload a plot of your measurements?