i am trying to build a spectrometer but need some advice.
at Vo, is it possible to interface with arduino pro mini? if yes can any of you advice me on how to do so?
Yes depending on the output you expect.
But you should change to a single rail op amp (on that will be happy with +5v and ground and not your old fashioned dual rail op amp. Micros don't like -ve voltages and getting rid of the need for one will simplify things.
Mark
holmes4:
Yes depending on the output you expect.But you should change to a single rail op amp (on that will be happy with +5v and ground and not your old fashioned dual rail op amp. Micros don't like -ve voltages and getting rid of the need for one will simplify things.
Mark
i am looking to have a plot on my pc that is "INTENSITY vs WAVELENGTH"
so the problem i have is..i do not know how i can connect my Vo to the arduino pro mini 328 
I can understand the left half of your circuit. You are using a photo diode in a reverse mode. Any light induced charges are swept to the -5V so the current that is proportional to intensity of light gets converted into voltage with a 1MV/A factor. I can't understand your second opamp. You are amplifying AC signal from your photo diode to approximately twice, correct? I suppose the output will be always positive so first measure with a scope with the range of light intensity you need, then decide whether you can hook up the output to arduino (0-5V limit). What is the typical voltage you get from this detector amplifier assembly?
liudr:
I can understand the left half of your circuit. You are using a photo diode in a reverse mode. Any light induced charges are swept to the -5V so the current that is proportional to intensity of light gets converted into voltage with a 1MV/A factor. I can't understand your second opamp. You are amplifying AC signal from your photo diode to approximately twice, correct? I suppose the output will be always positive so first measure with a scope with the range of light intensity you need, then decide whether you can hook up the output to arduino (0-5V limit). What is the typical voltage you get from this detector amplifier assembly?
so for the output i can connect to pin like #ad0 of the arduino?
Hi, what output do you expect to get out of the second amp when the signal fed to it is through a 10pF capacitor.
You will only be buffering the change in output of the first amp as the second amp has a gain of 2,, ie differentiating, and very little at that considering the value of the coupling cap.
Tom...... 
TomGeorge:
Hi, what output do you expect to get out of the second amp when the signal fed to it is through a 10pF capacitor.You will only be buffering the change in output of the first amp as the second amp has a gain of 2,, ie differentiating, and very little at that considering the value of the coupling cap.
Tom......
the 2nd opamp prevent loading of the circuit. correct me if i am wrong am not very good with these stuffs just started into this last week
What do you mean by loading circuit, which circuit? Is the second stage just helping the first stage (ganging up)? Do you have a multimeter and the parts to make this circuit? Make it and just measure with a meter? You are in the wrong stage to ask about arduino with a circuit you don't yet have and an output you don't yet know to expect.
siuhoong:
correct me if i am wrong
You are wrong.
That 10pF will stop any DC signal getting through. Also that front end is not very good either.
I would start again by looking at the signal you get from the first stage, my guess is that you will find the output bang against the power rail.