Current measurement with Lock-In Amplifier SR830

[chemist2011]

I have two current signals from a two color Si-photodiode/PbS-photodetector. I want to measure the signal with the Stanford Research Lock-In Amplifier 830.

I read in the manual that I can measure currents with the SR830. Does anyone have experience with this? Do I get better signals if I first convert my current signal into a voltage signal? I read that I could do this with the SR570 - but it seems me a little bit expensive. Is there any cheaper solution?

I am a chemist and electrical things are totally new for me - I will really appreciate any answer!

[f95toli]

I've never used the current input on the 830, but I can't see any reason for why you simply could not try it. Whether or not using a pre-amp like the 570 would help will depend on a lot of things, but of course mainly on the magnitude of the signal (but also on the output impedance of the diodes etc).
Do you know roughly how much current is coming from the diodes?

A cheaper solution than the 570 (which is pretty good) would be to build an amplifier tailor-made for you application, you can usually do quite well with a low-noise op-amp driven from two 9V batteries; but building one still requires some knowledge about basic electronics.