Photon counting using USB-6356

[Chaudhry123]

Hi all, 

I am new to labview and data acquisition hardware. I have looked into many posts but couldn't understand everything properly. 

I want to do photon counting/sec from two  single photon counting modules (Excelitas) using USB 6356, which I am accessing through DAQExpress. At the moment, I can access the data (time vs voltage) from apds using analog input in DAQExpress and count the number of photons by plotting the histogram (voltage vs photon counts/bin). What I want to do is to count the number of photons in real-time instead of voltage peaks on the y-axis. I can understand that I need to use the edge-trigger so that every peak is counted as a photon, but I am not exactly sure how to implement that physically and in DAQExpress? I am also wondering if it's possible to open labview (.vi) files in DAQExpress? Any help would be greatly appreciated, many thanks in advance. 

Best, 

Arman

[Henrik_Volkers]

If you want to count something you should try to use a counter 🙂

I don't know how you signal looks like, nor you expected count rate and don't have access to a 6356, but the spec told me that you should  able to use the analog trigger as an counter input.

(or use it as an single sample trigger and count the samples, however there migth be something like a trigger rearm delay..)

at least you always can add more gain and trigger a PFI input 😄

EDIT: Have a look at the examples (help-find examples) and well yes, you will  have to learn more about LabVIEW and DAQmx. Try to avoid the express vis .. look at the examples with the more advanced DAQmx vis, you will need to use them anyway if you need to make profit of your hardware... the express vis are more general.

[Chaudhry123]

Thanks for your reply Henrik. I am already using analog trigger with PFI to count the (added )number of events happening in a certain amount of time. It just adds all the events in the given amount of time, but I want to count the individual number of events at certain time (every ms for 1 sec) which I think is possible if we reset the counter after every count. It doesn't seem to be the case with DAQExpress because the minimum time interval one can measure is 1 sec.I have already got the labview and started learning to benefit from the full functionality of my hardware and get the desired results. 

Many thanks for your suggestions!

Greetings, 

Arman

[Henrik_Volkers]

set the counter to count events and sample the counter every ms or s without resetting  , the difference is easy done 🙂

with a 32bit counter you might get an overflow after some time, but that is easy to detect and handled (just like the pt by pt phase unwrap ;))