Overview: Use "MOD-IN" port of KLC for faster switching between voltages

 

Details:

 

In order to produce polarization states extremely fast we wish to rapidly change/sweep the voltage across LC and so we chose to use "sine" for making the variations in labview. Although we removed most of the logic for the iteration using sine, we are still a bit limited by the voltage controller itself. 

 

Thorlabs advised to not use the normal V1 as input but rather use an external input.

 

So, I connected the output of one KLC(SN-38) to the "MOD IN" of another KLC(SN-52). Here the output voltage of the controller(SN-52) is set by the external input signal of the “MOD IN” port. The 0~5.0 V DC external input corresponds to the output voltage of 0 to ±25 Vrms. For visualization, I connected the output of SN-52 KLC to the oscilloscope.

 

The variation observed is as follows:

 

(It did behave randomly sometimes though. For example, it used to provide the same output irrespective of change in input)

 

This worked both with the Thorlabs application and Labview. I was able to integrate the same in our labview. See Fig 1 for a better understanding. The first plot in labview shows input voltage which is varied using the sine function. and the output is shown in the second plot.

 

Next Step:

Investigate issues with data resolution of this new output and check its consistency.