Noise

Measurements of noise  for various reset times and signal levels during the SWS instrument level tests resulted in the following characterization of the noise behaviour of the F-P detector and integrating preamplifier system:

• Noise at low signal levels is independent of signal. Here, noise as a function of reset time can be approximately modelled as the quadratic sum of a constant read noise term and a dark current noise term increasing with time. Deviations from this model exist but may be ignored for simple sensitivity estimates
• At higher signal, SNR improves only with the root of the signal, indicating dominance of shot noise.

with S the signal in V/s and dimensionless (happens to be equal to the reset time in seconds). The empirically determined noise parameters (read noise, in V/s) (dark current noise, in V/s), and (signal shot noise, V /s ) for the two F-P detector materials are summarized in Tab. 5.3.