ABSTRACT
A detector is a device that is capable of transforming the energy
distribution into a flow of interpretable information. It senses an
optical signal within its field-of-view, regardless of its angle of
incidence, and converting it into an electrical signal (current or
voltage). The process involved here is the quantum process, which
is statistical. Given a certain electric field, the number of charges
N released is statistically related to the exposure W (wave power multiplied by time) by Einstein’s relation, W = N¯ω, with N as an integer having mean value N¯ , and obeying Poissonian statistical distribution. The probability of certain number of photons, Nph, being detected in a certain time interval, P(Nph), in which the average number of photons detected is N¯ph, is given by
P(Nph) = (N¯ph) Nph
Nph!
