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I am looking for a somewhat cheap way of measurin small distances ( >0.1 inch) between an object and a sensor, are there any good ways to do this? I am considering the component from a flatbed scanner, but I am not sure how I would make use of this. It would be preferred to use some kind of mechanism that uses absolute positioning, so it doesn't get thrown off, but a very accurate absolute positioning method would work too. Suggestions would be appreciated.

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  • \$\begingroup\$ Contact or non contact? \$\endgroup\$ – Decapod Oct 11 '16 at 18:48
  • \$\begingroup\$ How are the object and sensor mount connected? E.g. a lathe tool and a workpiece, or two jaws of a vice, or an object randomly placed in front of the sensor? How accurate does it need to be? \$\endgroup\$ – Andrew Morton Oct 11 '16 at 18:49
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    \$\begingroup\$ Either define "somewhat cheap" or give us a desired resolution/accuracy. No point suggesting a £6000 capacitance sensor with 0.5nm resolution if you don't need something that good. \$\endgroup\$ – Jack B Oct 11 '16 at 18:50
  • \$\begingroup\$ Get a cheap dial caliper, and hook it up (spring-loaded.)so it is always measuring your separation. This will give about 0.001 inches resolution. \$\endgroup\$ – WhatRoughBeast Oct 11 '16 at 19:59
  • \$\begingroup\$ @JackB Looking for something hopefully accurate to about 1/1000th of an inch \$\endgroup\$ – 888 Oct 11 '16 at 22:23
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If contact is okay, you can use a digital dial indicator. They use an incremental measuring method internally so they need to be zero'd. Accuracy is about 0.001" for the cheap ones and range is typically at least an inch.

Price ranges from about $25 to $500 depending on brand and performance.

You can interface to the internal battery-powered electronics- they usually have a proprietary serial interface with 1.5V levels. There are a few standards for the interface- Mitutoyo is one- and the Chinese ones are generally similar to each other (and different from Mitutoyo).

https://images-na.ssl-images-amazon.com/images/I/41J9XbT04pL._SY300_.jpg

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