Hi,
I am trying to observe interference from a 1550 nm LASER on Thorlabs (FGA21 - InGaAs Photodiode, 14 ns Rise Time). I have the photodiode connected in Photovoltaic mode across an OP27E Op-amp. When I observe the output signal from the Op-Amp there is a lot of noise and also there is a very large DC offset (the photodiode current is 2.38 mA). I can observe the amplitude variation when I distort the mirror alignment but I cannot observe a fringe pattern due to the noise. I have a few questions:
1) Due to large DC offset the maximum feedback resistance is limited to 4.7 Kohm (voltage supply +- 15V ). Should I just add an HPF to remove the DC offset followed by amplification stage or should I maximise the voltage output from the transimpedance amplifier and finally remove the dc offset.
2) Is it better to use AD549/AD8651?
I am trying to observe interference from a 1550 nm LASER on Thorlabs (FGA21 - InGaAs Photodiode, 14 ns Rise Time). I have the photodiode connected in Photovoltaic mode across an OP27E Op-amp. When I observe the output signal from the Op-Amp there is a lot of noise and also there is a very large DC offset (the photodiode current is 2.38 mA). I can observe the amplitude variation when I distort the mirror alignment but I cannot observe a fringe pattern due to the noise. I have a few questions:
1) Due to large DC offset the maximum feedback resistance is limited to 4.7 Kohm (voltage supply +- 15V ). Should I just add an HPF to remove the DC offset followed by amplification stage or should I maximise the voltage output from the transimpedance amplifier and finally remove the dc offset.
2) Is it better to use AD549/AD8651?