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Thorlabs QPD (PDQ80A) in NI SCB-68A



I am working on a project in which I am going to use thorlabs QPD (PDQ80A) to

track the position of a colloidal particle in an optical tweezer. I am using a ±12V

external power supply (Thorlabs, LDS12B) to power up the QPD. I am having a 

hard time in connecting the QPD to NI SCB-68A board.


Does anyone here had the experience in hooking up this QPD 

to the NI board I mentioned and read out the data using LabView?


This is the QPD that I am using

and this is the NI board I am using 



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Message 1 of 2

Hi Jadesboy


I don't have experience with thorlabs QDP, but I have experience with NI DAQ SCB 68 products.


From What i was able to grasp from the manual, the pinout gives you the signals you need to connect the two : 

Pin 1 , 2  - -4 to +4V

pin 3 - 0 to 4 V

pin 4 - +5 V

pin 5 - Common 

pin 6 - -5V



pins 1 , ,2 , 3 you connect to the Analog input of the NI DAQ. 

The setup has to be differential to read the negative values .

Check page 2-6 of the SCB68 manual for description of the connections. 


Without programming, you can use the NI max to quick test the signals coming from the  QPD for sanity check before jumping into labview programming. 




Message 2 of 2