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Synchronizing analog output and input for imaging

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As per my project I have to detect the cells from the sample have to make bounding box onto the cells and than have to scan the bounded area using two small beam galvano mirrors. so I have divided task into three parts,


In First, I have to detect the cells from the sample then have to make bounding box onto the detected cells and have convert the bounded area into the ROI.


In Second I have to convert ROI rectangle corner coordinates into meaningful corresponding parameters for your X and Y galvo mirrors.


In Third, I have to scan the bounding box rectangle area in order to get the info about the cells property.


Your question: I'm still not clear on whether a fixed galvo position is controlled by setting 2 constant DC voltages or 2 amplitudes for AC sine waves.


Answer : Yes I am using 2 amplitude values to generate AC sine wave to operate X and Y mirror.


Now I have two VI, One can detect the cells, make bounding box onto the detected cells and convert it into the ROI, Second VI can useful for the scanning of cells by using the two galvano mirrors which operated by sine wave AC signals.


So first  and last step has achieved and have to find a way to compete the second task also have to sync the AI and AO, so for sync operation I am following the threads you pointed me before.


Thank again.


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Message 21 of 23

I quickly skimmed the link you gave to the galvo mirror system.  It appears to be rotational positioning system whose angle is proportional to a DC input voltage.  If you feed it a sine wave on an axis, it will oscillate as it tracks the sine wave of commanded angles.  A sine wave input produces a sine wave motion output, *not* a constant position output.


In past threads I've joined, a typical pattern to "scan" a rectangular region would be a repeating fast ramp (i.e., a sawtooth pattern) on one axis and a slow stair-stepping ramp on the other axis.  The # of *repeated samples of the same value* in the slow stair-stepping ramp would be equal to the # of samples in one cycle of the fast ramp.  (You may need to adjust the fast ramp pattern slightly to accomodate the real-world speed limit of the mirror system.  You probably can't get from one extreme position to the other in one sample interval.)


I'd recommend working on the signal generation algorithm to make sure things look reasonable on a graph first.  Then I'd try generating those signals with AO, but perhaps at a much slower than normal speed.  (I'd target something like 0.2 to 0.5 seconds per fast ramp cycle.)    Sync with AI can wait until after the more fundamental stuff is worked out.



-Kevin P

CAUTION! New LabVIEW adopters -- it's too late for me, but you *can* save yourself. The new subscription policy for LabVIEW puts NI's hand in your wallet for the rest of your working life. Are you sure you're *that* dedicated to LabVIEW? (Summary of my reasons in this post, part of a voluminous thread of mostly complaints starting here).
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Message 22 of 23

Hi Kevin,


I went through the manual again and I found that I can operate it with sine wave(250Hz) or Sawtooth wave(100Hz) or Triangle wave(175Hz) or Square wave (175Hz) with voltage range +-10V, I have attached the input parameters to drive the instrument.


For the scanning operation I made VI which can scan according to the applied input parameters.

So scanning is working properly and no need to make any change and I have attached the video in which you can see how it scans.


I also successfully able to convert the pixel values of bounding box into the corresponding values for X and Y mirrors input.


sync of AI and AO is also working properly.


I have one problem but not sure right now so I come to you when I get all information of the problem.


Thank you very much for the help.


Have a nice day.




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Message 23 of 23