Would FPGA be appropriate to construct a "circuit" for radomly firing a laser based off two PMT signal ~ 500us apart?

[StanleyK]

Good Afternoon Everyone,

My question is pretty basic.  I'm attempting to design a system for randomly firing an excimer laser at particles based on their light scattering signals.  The hardware is pretty easy to understand and consists of three lasers.  Two of these are light scattering lasers placed a known distance apart and the other laser is our ionization laser, an ArF Excimer.  The incoming particle passes through the first set of lasers creating two light scattering signals.  Using the time delay between the signals and the known distance between the lasers we can calculate when the particle is in the source region and fire our excimer laser.  We've been having alot of trouble with accomplishing the triggering of the laser.  LabView Real Time isn't giving us a consistent trigger delay and our instrument shop is hesitant to design a circuit for this application since we want it to be fairly flexible given our future applications of the instrument.  Would FPGA be able to take in these PMT signals and consistently output a pulse to fire the laser at the appropriate time?  If so, which specific type of FPGA should I be looking into?  

Thanks for your help,

StanleyK 

[Andrew_E]

Hi Stanley,

I think FPGA will definately be better for your application if you are experiencing trigger delay issues, because now all you are using is hardware instead of software on hardware and it is completely deterministic.A couple of questions before we get started. How fast do you need to output your signal and take in inputs for these particles. (i.e. how fast do you need to take in data aquisition and how fast do you need to trigger).  As for what FPGA you should be looking into there are a few options NI offers. If you want the top of the line FPGA and happen to have a PXI chasis I would recommend the PXI-7854R Series board. This board has a Virtex 5-LX110 FPGA Chip , takes inputs at 750 KHz/channel and sends outputs at 1 MHz. If not there are a few other options the PCI-7833R which has a 3M Gate FPGA takes data in at 200 Khz and sends outputs at 1 Mhz. There is also the CRIO 9103/9104 which would also require the 9014 controller. Then you can put specific input and output modules into that. You could also use the Sbrio 9642 which runs at 400 MHz, has a 2M gate fpga and has 32 AI, 4 AO, and 32 24V DIO lines.

Along with all these FPGA options which are the best of the best because it seems like you may want to be safe with the overkill if you want to shoot particles with lasers, you will need FPGA module for Labview to program them.

Regards,