I was trying to work with a photodiode that is supposed to detect very tiny amount of light. Using different kind of lenses I succeeded amplifying the light amount that will fall on the photodiode. Now I have to work on the photodiode’s ability to convert the light into electrons / increase the pd's sensibility. Hence I had experienced only little success getting the photodiode to receive the small amount of light and convert it into electrons.
Now I learned that an Op amp will significantly help to amplify the signal provided by the photodiode. Moreover I learned that a lock-in amplifier might be a solution in my case. Being a rookie in electronics I first want to work with an op amp (lm358n) and then try my luck with the more complicated lock in amplifier. Working on a circuit with an op amp I came up with this circuit (see figure) considering the suggestion given in this post as well How to Use SFH235 IR Photodiode Correctly?.
However the photodiode does not really react to the provided light. I guess there is something wrong with my circuit.
Can anyone give me a hint what I am doing wrong or what I have to do to get it right?
Datasheet OP Amp http://www.ti.com/lit/ds/symlink/lm158-n.pdf
Datasheet Photodiode http://www.farnell.com/datasheets/57158.pdf
As Ignacio Vazquez-Abrams mentionied I have just test the circuits provided in the http://www.ti.com/ww/en/bobpease/assets/AN-31.pdf document.
Indeed the sensitivity of the photodiode has increased. One question left: The circuit on the right side makes use of an LM 108 and a capacitor on pin 8 ( due to the datasheet pin 8 of the op amp stands for Comp). Not having this pin on L358 what can I do for that?
Morever the arduino analog pin normally indicates a value btw 0-1023. Now using the op amp I get a maximum value of 767 ( this means approx. 3/4 of 1023). Is there any particular reason for that or am I doing any mistake?