Delay generator for laser system

[ryder_2010]

I'm looking into purchasing a new delay generator for a laser setup. The setup includes control through either TTL, 5 V pulses, or < 5 V pulses. I'm not quite familiar with some of the terminology in the specs. I need to be able to have a delay step size of around 50 ps. I've been looking into the PXI-6562, which says it has a delay range of "1/256 of sample clock period for clock frequencies ≥ 25 MHz or 60 ps, whichever is greater". Our laser system has a repetition rate of 10 Hz. Does this mean that we will have a delay range of 60 ps? Is this the same as having a step size of 60 ps? 

[John_P1]

Hi ryder_2010,

The 6562 doesn't sound like the correct hardware for your application.  It's a digital waveform generator/analyzer which uses LVDS logic levels.

Instead, I think you should be looking at the GFT9404, which is designed specifically as a delay generator and offers 1 ps delay resolution (on 4 channels).  If you have any questions about this module feel free to post back--I actually haven't yet used it myself but I can forward this forum along to somebody who is more familiar with it if necessary.

Best Regards,

[ryder_2010]

I actually did look at the 9404 as well, it just isn't a great fit for our application. I don't need resolution as low as a single ps, and I need something lower than 5 ns. I would also prefer something with at least 12 channels. Is this the only delay generator that is offered by NI, or do I have other options? Also, what signals is LVDS capable of sending?

Thanks for the help. 

[John_P1]

Hi ryder_2010,

LVDS stands for Low-voltage differential signalling--the logic levels are as follows:

I took the image from here, there is actually a typo in that 1V should correspond to V_OL (not V_OH).

So, the logic levels don't line up with your requirement.  There are other HSDIO products with data delay that have other logic levels, but nonetheless I really don't think data delay is what you are looking for either (you can read more about it here).  It is typically used to delay generation/acquisition data relative to a sample clock (very useful when testing digital interfaces that require settling time etc.).  You might want to provide a timing diagram to help show what exactly you need and how the various channels fit in--perhaps it might be possible with HSDIO but I'm not terribly optimistic. 

It sounds like you are looking for a delay generator like the GFT9404 but with more channels.  Unfortunately, NI does not currently have such a product available.

Best Regards,

[Kyle_A.]

Hey ryder,

We have a product that we have just released, the PXIe-6556, which sounds like it may be a compatible fit for your application.  It has data delay and data deskew features which can delay down to 30 ps of resolution per channel, 24 channels and has a voltage range that goes from -2V to 7V. 

Take a look at the product and its specifications and let us know if you have any questions.  If you need to contact me directly, send me a private message and we can discuss your application further.  Thank you.

[straight-shooter]

If you wish 1 ns and 12 channels, you may gang 2 BNC 575's, http://www.berkeleynucleonics.com/products/model_575.html, together as a cost-effective alternative.  The resolution is 250 ps.