Particle tracking

Most of the particle tracking protocol is described in the paper. The protocol is as follows.

1. The laser focal position is scanned in the xyz directions (in our paper, the piezo stage was scanned) while measuring the ND fluorescence intensity. The scanning ranges and scanning steps for each axis were

   (Xrange 480 nm, Xstep 40nm),

   (Y range 480 nm, Ystep 40 nm),

   (Z range 640 nm, Z step 40 nm).

   The front panel of LabView-VI is as follows.  

   
   

    

2. The obtained data of fluorescence intensity vs xyz positions were fitted with a Gaussian function to determine the center position.
3. The piezo stage was moved smoothly to the determined center position by five steps of ~20 nm every 2 ms for the respective axis.

4. This re-positioning process takes 3 s and is performed every 4 s during the four-
   point measurement of ODMR.

    

For other information that we do not explicitly describe in the paper is...

1. We do this using LabView software (see above VI front panel).
2. The control voltage is supplied from NI-DAQboard(USB-6343 BNC) to the piezo controller (Piezosystemjena, NV40/3) in the closed loop mode.
3. The laser focal position is scanned in the xyz directions (in our paper, the piezo stage was scanned) while measuring the ND fluorescence intensity.