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Rastor Scanning

Hi,

     I recently purchased a pair of Galvo scanning mirrors and would like to operate them using LabVIEW. I need to give two different ramp signals for X and Y mirrors Separately, where I can change the lower and upper voltage limits as well as the slope of the ramp. I tried the same using the arbitrary wave generator, but there is no option for modifying the signal in between. Does anyone know of example on such an application as raster scanning?

Many Thanks,

Nijas

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Message 1 of 9
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I have used a galvo pair in a project quite some time ago. I controlled them using a fairly low spec multifunction DAQ card (using the analog outputs).

 

What is the model of arbitrary wave gen? 

Whats is the raster pattern you are hoping to acheive?

How fast does it need to go?

Whats is Vmin and Vmax for the galvos?

 

0xDEAD

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Message 2 of 9
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Hi,

     I tried the arbitrary wave gen which came with LabVIEW Instrument launcher. The shape of the pattern is attached, here I want to control the voltage(MInimum -8 and maximum +8) and the slope of the ramp signal. Maximum speed expected is about 75KHz and I do have all the DAQ cards needed for the same.

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Message 3 of 9
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@NIJAS_MOHAMED wrote:

Hi,

     I tried the arbitrary wave gen which came with LabVIEW Instrument launcher. The shape of the pattern is attached, here I want to control the voltage(MInimum -8 and maximum +8) and the slope of the ramp signal. Maximum speed expected is about 75KHz and I do have all the DAQ cards needed for the same.


What DAQ card will you use?

Is 75KHz meaning 75000 complete raster scans per second, or 75KHz analog output rate rate?

How fine is the raster grid (how many discrete steps between -8 and +8V)?

 

I am just trying to get a feeling for what you are actually trying to achieve.

 

I suspect you are best building the ramps using the either for loops or "ramp pattern" vi, then feed them to the AO channels.

Depending on the hardware you are using you might need to synchronise the sample clocks.

 

0xDEAD

 

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Message 4 of 9
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Hi, 

     I'm using PXIe-6363 as my DAQ card. 75KHz is the analog output rate, as that will be the maximum speed in which I will operate my camera.  The raster grid should be as fine as possible, as steps would induce vibration/jittering to the mirrors.

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Message 5 of 9
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As fine as possible isn't really too quantitative. You can calculate the code width of the AO channels by considering their voltage range and resolution to get the minimum possible step size in terms of voltage, but this is often finer than the accuracy you can expect from the device.

You also probably don't want too much overlap between adjacent lines in the raster. So making it as fine as possible is probably wasteful.

 

How large is the area you need to scan over and what is the spot size (I'm assuming were dealing with a laser here).

 

0xDEAD

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Message 6 of 9
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Hi, Thank you for your information. The resolution of output voltage needed is about 5mV (It's within the DAQ limits) which is equivalent to about 0.01-degree movement of the mirror. Spot size is currently 1 mm and the reason why I make the movement slow is to reduce the jittering of the mirrors. In order to reduce the overlap, what I was thinking was to reduce the imaging speed.

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Message 7 of 9
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What does the angle equate to in terms of distance on the sample,or how far away are the galvos from the sample so we can work it out?

 

What actual raster pattern on the sample are you wanting to use (obviously there would be more scan lines, I just wanted to show the rough patterns). Is it one of these or something else?

Assuming black is acquiring moves and red is non-acquiring.

raster.PNG

Will your camera always be free running or will you have some trigger/sync?

 

If you give more information, people will be able to help/advise you better. I feel like I am interrogating a mob boss here.

 

0xDEAD

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Message 8 of 9
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Hi,

     I cannot give a general angle- distance equivalency, as the distance between the sample and the galvo mirrors based on the imaging lens which I use. From the figures which you gave, the first one is the method which we are planning to use and the camera will not be free running, it will have a separate trigger so that we will be imaging only on requiring region.

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Message 9 of 9
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