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1) Then your flow rates are even higher... If you are sampling at ~100kHz, then the duration of your signal from a gas particle is probably only one sample long, correct? The flow rates I mentioned are based on the readout from a flowmeter calibrated for the kind of gas that we're monitoring...

1) What are the scales on your oscilloscope traces? Generally, it's constantly autoscaling. Looking at the pics I posted (these were taken a couple of months ago) we're looking at a voltage range of ~7mV. 2) What does an aerosol particle trace look like? An Aerosol particle looks like a single...

I suspect it's not the chip :) NI sbRIO-9631 - Embedded Device with AI, AO, DIO, 1M Gate FPGA - National Instruments Also, I'm using the 9631 to do my high speed sampling, but I'm using a separate module (USB-9239) to do the data acquisition on my computer simultaneously and comparing the...

1) Do you get a same or similar noise? I have attached a sample of the signal that is generated when bumping the fiber at the connections. What you are looking (and what almost has an impact on what I'm doing) is the vibration from this impact. My sample rate is too high to consider movement of...

1) Have you considered cell phones? Yes, we have considered this. Unfortunately, I have recorded these issues over night when no one has been here. Also, we barely get any kind of reception here at all from the tower, so I don't think that is the culprit. Also, the problem stays the same (not...

1) Is a laser diode power controlled by any feedback? The laser driver board has a current monitor built in to the circuitry. We set it per laser diode that it powers. Each diode comes in a package that is labeled with the values for that particular diode. 2) Can you switch it to a plain...

I have very limited space available for added equipment. I have suggested a beam splitter as you mentioned, but was shot down because of available space. This is all going into a rather small explosion proof enclosure. We went with a PMT because of the required sensitivity. A photodiode will not...

Unfortunately, we have no options (that we're aware of) for actively cooling the diode. We have the diode mounted to a pigtail between an aluminum collar and a steel,threaded containing ring that screws into the lens housing and holds everything in compression and is very stable. I have also...

Thanks for your reply I've monitored the input and output power of the driver board, various power supplies, bias voltage for the PMT. I've monitored at low speed over a 24 hour period, and at extremely high speeds (too fast to reasonably log the data) during some of these episodes. I have gone...

I am using a laser diode to count aerosol particles flowing through a gas stream. The refracted light is being funneled to a photo-multiplier via fiber optics. When there is no gas flowing (and therefore no particles) we are seeing some strange results from the output signal of the...