Very low cost way to record distance from 1/2" to 5/8" at .01 precision?

[jdunfee5]

I am setting up a test rig that will need to measure the distance between two plates in a vacuum. The plates will initially be placed at 5/8" apart, and I need at least .01" precision. I need to do this at 5 locations, so cost is a major issue. I really need to keep it under $75 each. Preferably under $50 each.

Of course, I can obtain low cost dial indicators, but ideally I would like something that I can connect to a computer to record data. The actual information can be sent via USB, or simply be analog voltage or resistance that I connect to an analog-to-digital converter.
I have been attempting to find this on the internet, and used such search terms "digital indicator" but haven't been successful in finding anything in my price range that provides an external data or analog connection.

Any suggests about where specifically to look for this type of low-cost instrument?

Thank You,
Joe Dunfee

 

[IRstuff]

Perhaps, it's your choice of search terms: "linear displacement sensor" comes up with all sorts of hits:

http://www.mouser.com/Sensors/Linear-Displacement-Sensors/_/N-zqfc/

http://www.omega.com/section/displacement-proximity-transducers.html

http://www.positek.com/linear.htm

http://www.rdpe.com/us/men-disp.htm

However, your price bogey might be a bit optimistic.

TTFN
faq731-376

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[danw2]

wireless dial gauges:

http://www.tecnomatrix.com/captor-system/captor-s/

 

[jdunfee5]

Thank you both for the ideas. The Captor system seems to be a modification to an existing digital gauge, which converts it to being a wireless data acquisition system.

The Linear Displacement Transducer was a good phrase to search. Most of the effort in an Internet search when you are looking for something outside of your normal industry is coming up with the correct search terms. That is why I think computers will never reach the Star Trek level of voice command. They just aren't smart enough to know what you are talking about, unless you know what the correct words to use for its matching algorithm.

With our pricing limitation, I suspect that I will need to make something myself. The idea of modifying the Gauge gave me an idea. Perhaps I can simply purchase some linear potentiometers, and adapt them for a measuring device. I just came across a line of precision linear potentiometers here, which were designed for measurement. Again, the task of knowing the correct internet search terms seems to be the main task nowadays.

http://www.potentiometers.com/select_linear.cfm

Thanks again,
Joe Dunfee

 

[ScottyUK]

Something like Vishay's resistive bridge is probably closer to your budget than an LVDT:

http://www.vishaypg.com/docs/11350/hs.pdf.