Where ktot is the modulation contrast , S is the number of (active) signal electrons, N is the
equivalent number of noise electrons (including shot noise of active light, back ground light and
dark current as well as thermal noise, reset noise, system noise and ADC noise), N phase
is the number of measurements and λmod is the wavelength of the modulation signal in meters. An
alternative notation of this product of k ’tot and S’ is fully equivalent , where S’ represents the
complete number of integrated electrons, including background light and dark current and k’tot
represents the overall system contrast , also including dark current and back ground light offset .
Please note that for both cases the product of ktot and S represents the “active signal share” after
integration (demodulation amplitude ).