its a photocell. its an experimental apparatus, for photoelectric effect!! the currents i will be dealing with, is from some pA to max 100pA !!
the bias, is my teachers opinion, so i cant do much about it. but the reason for that, is , we have to take measures, for the noise in our signal, so everything has to be guarded, by extremely low input current op-amps (Which are expensive, and we cant use many), and so on...
the output voltage, has to be 1mV per 1pA!! i have also concluded to Vbias-(I*RF) , but i cant seem to be able to use it, since Vbias, will always dominate the output??
i will look on the documentation posted!!
the circuit so far, looks like this : (the current source, represents the photocell... couldn't find the correct symbol!