Ultra Start KE-6 Specifications download pdf (Page 101)

Version 1.1 rev Jan 2013

Page 101

iXon Ultra

Appendix

A.1.12 - NOISE

A.1.12.1 - Pixel Noise

The Pixel Noise is the variation in the pixel’s charge level when exposed to a constant signal ux over a signicantly valid

period of read levels. The pixel noise is normally expressed as the value of the Root Mean Square (rms) of these variations.

NOTE: The rms value is approximately x 4 to x 6 smaller than the peak to peak variations in the level values read

from the pixel.

Pixel Noise has three main constituents:

• Readoutnoise

• Shotnoisefromthedarksignal

• Shotnoisefromthelightsignalitself

Shot noise cannot be removed due to the laws of Physics. Most simply dened, shot noise is the squareroot of the

signal (or dark signal) measured in electrons.

A.1.12.1.1 - Readout Noise

Readout noise is due to the amplier and electronics. It is independent of dark signal and signal levels, and is only

very slightly dependent on temperature. It is present on every readout, as a result of which it sets a limit on the best

achievable noise performance.

A.1.12.1.2 - Shot Noise

Shot Noise is due to the basic laws of physics and cannot be removed. Any signal, whether it is a dark signal or a light

signal, will have shot noise associated with it. Shot noise is a statistical variation in signal level which follows a Poisson

distribution. The shot noise relates to the generating signal by the following relationship:-

If the signal or dark signal = N electrons, then the shot noise is the square root of N.

You can do nothing about the shot noise of your signal, but by choosing minimum exposures and operating the EMCCD

at suitably low temperatures, the dark signal, and consequently the noise from the dark signal, can be reduced.

A.1.12.1.2.A - Shot Noise from the Signal

Shot noise is caused by dependence on the signal generated by the light falling onto the sensor.

A.1.12.1.2.B - Shot Noise from the Dark Signal

Shot noise from the dark signal is related to the electrons generated within the sensor, Dark Current etc. Therefore it is

dependent on the exposure time and it is very dependent on the temperature.

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Ultra Start KE-6 Specifications Page 101