Look at the link, specifically "About Lock-in Amplifiers".
To get I & Q (X & Y) you need to multiply your input signal by a Cos and Sin of the same frequency as your signal. I would suggest for now, forget about the AO, acquire the sinusoidal data then multiply it by your reference. (If you want to use the AO, then you need to acquire both the reference and signal and multiply them together, that is, you need to channels of AI input. Actually 3 if you want both I & Q (X & Y), because you need a sin and cos for both.) You then need to low pass filter the data, this is your "time constant" on the lock-in. Once you do that you will have I & Q (X & Y) for your signal, you should then be able to reconstruct your WMS signal.
(Typically for WMS I & Q (X & Y) are considered equivalent; for 1f detection you should get a derivative of your lineshape from either I & Q (X & Y), they should be out of phase with each other. One component may be larger than the other depending on the phase angle between your reference and signal.)
mcduff
