Determining DAQ for Galvo Control

[QDSpec]

Hi all,

I've recently purchased a dual axis galvo set from ThorLabs (GVS012) and I'm trying to figure out how I'll interface with it.  It came with 2 servo boards, and the accompanying manual says I should use a DAQ that has dual, biploar -10V to 10V  DAC analogue output (differential), must be able to sample at least 5kiloSamples/second, and has at least 16bits of resolution on the DAC.  I'm a little overwhelmed by the choices that'll fit my application.

For context, I'll be using the galvos in an epifluorescence setup to raster scan a laser along a sample and identify where my fluorescent molecules are located. The beam will be coming off the galvos and into the back of an objective lens, which will then focus the light down onto my sample.

Further, I'd like to know how I might, after acquiring the DAQ, control the galvos.  How do I send a waveform to the servos?  How do I change the voltage steps?

[ShamWOW!!]

Hello QDSpec,

I just sent you a private message. Let me know if you would like to talk more about finding a DAQ device for you.

Best,

Shamik C

Applications Engineer 

National Instruments 

http://www.ni.com/support 

[BrioMex]

Shamik C., I have purchased this galvanometer as well and I will appreciate any support choosing the DAQ needed.

The minimum recommended specifications for the DAC outputs are:

* Dual bipolar -10V to 10V DAC analogue output channels (differential).

* DAC clocking frequency higher than 20kS/s (Kilo Samples/Second), higher sampling frequencies like 100 kS/s are recommended (inputs have a 7 kHz low pass filter).

* 16 Bit DAC resolution and low out impedance (<= 50 Ω).

Best regards,

Manuel Briones.

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[QDSpec]

Manuel,

If it helps, I ended going with the USB-6002.  Take this with a few caveats.  The first being that I do not care about the speed at which I scan, and so didn't need a DAC that could push 20kS/s.  Additionally, the USB-6002 has 2 analogue outputs, which is sufficient if you're only running the galvos on an analogue signal. 

I ended up writing my own quick and dirty LabVIEW VI to achieve the type of control I required.  I'd be happy to upload it if you need it.

[BrioMex]

QDSpec,

I will appreciate if you can share your VI since I have not made contact with any DAQ before. About the sampling speed, I need (1024 * 500)  512k per second. I suppose using a 900k sampling DAQ will be enough but I´m not sure. 

[QDSpec]

Manuel,

Attached herein is the VI.  I'm not sure how you might work your required sampling rates into the given VI, as my application is drastically different.  In any case, I think this is a good starting point.

[BrioMex]

Thank you QDSpec!

I'm sure it will be very helpful. 

Thanks again.

Best regards,

[BrioMex]

Thank you QDSpec!

I'm sure it will be very helpful. Hopefully I will be able to understand your VI (I'm not an expert LabView programmer).

Thanks again.

Best regards,

[mdaliaamir]

Hi Shamik,

I have exactly the same query. Could you share with us (or me) whatever guidance you provided about how to begin with a galvo?

Thanks!

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@ShamWOW!! wrote:

Hello QDSpec,

I just sent you a private message. Let me know if you would like to talk more about finding a DAQ device for you.

Best,

Shamik C

Applications Engineer 

National Instruments 

http://www.ni.com/support 

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[Rujia]

Hi,

I wonder if you can tell me the electrical connections between the 2-axis galvo driver board and your NIDAQ USB with 2 analog ouputs. Since the tholabs munual gives me the instructions that we should use the three wire: one + the other - and a ground wire. I can see that the ground wire should connect to the ground in NIDAQ. But I was confused about how to connect the other two +/-  wires. As you said before, one analog output can control one-axis galvo, which means the + wire should connect to one analog output. So, what about the - wire? Do I need to also connect the - wire to the ground of the NIDAQ? Thanks a lot.

Rujia