EMCCD Tutorial
Q8 What is multiplication noise?
Multiplication Noise, also known as ‘Noise Factor’, is a by-product of the probabilistic
nature of signal amplification technologies and affects both EMCCDs and ICCDs. When
a signal electron is subjected to a gain of x300 for example, it does not follow
that every electron inputted into the gain register will be amplified to exactly
300 electrons. There will in fact be a distribution of output signal, with a mean
value of x300 the input signal. In fact, the noise factor that defines this distribution
has been measured to be significantly higher in ICCDs. The noise factor of EMCCDs
is well theorized and measured; to account for it you increase the shot noise of
the signal by a factor of square root 2 (~x1.41). This gives the new ‘effective
shot noise’ that has been corrected for multiplicative noise. The effect of this
additional noise source on the overall Signal to Noise ratio can be readily viewed
in the S/N plots on this site. Multiplicative noise can be overcome through use
of EMCCDs in photon counting mode. The only EMCCD that is recommended for effective
photon counting is the Andor Technology iXonEM+ DU-897.