Hi,
I am now given a project which is Frustrated Total Internal Reflection (FTIR). Basically there is a lot of way to extract the information signal from IR sensor like DC approach, AC approach, transimpedance amplifier. I found that Lock In Amplifier is suitable for me to use in my project because the voltage across the IR receiver part will be small like mV and the noise will be high since the ambient light or sun light able to disturb the light wave emitted from IR emitter. Currently i download the NI lock in amplifier VI and i try to translate into DAQmx version. The VI can run but I am not sure that VI was translated correctly or not. Can just help me to check it out? Now I am using NI USB6366 to do the lock in amplifier as well. Here are some questions that i want to ask:
1. From the NI lock-in amplifier start up kit user manual, for the configuration section on PAGE 13/20, I found that the first channel in the channel list should be used for the signal and the second channel in the list should be used as the reference input. I am confusing with this because i just able to create a channel for acquisition puspose and the channel is used to wire the input of DAQmx start.vi. May I know another channel where should i put?
2. If USB 6366 able to use with lock in amplifier VI, how to acquire the signal from the IR receiver? I wire the A0+ to anode of IR emitter and A0- to cathode of IR receiver, is it correct? this wiring is used for the signal or the reference input?
3. The generation of signal to IR emitter also can be done inside the lock in amplifier start up kit? As i saw the signal generator function inside there but I am not sure what the function is.
4. lock in amplifier able to amplify my IR receiver's signal? or I need to build up a new circuit to amplify my signal then just feed it to the lock in amplifier VI?
Thanks for all the reply. Really need help on this. thanks
Attached will be my modified VI for NI lock in amplifier start up kit.
