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Ram's Electronics Page

I have broad interests in analog and power electronics and embedded computing, but my original content currently concentrates on capacitive sensing and the practicalities and aesthetics of classic test equipment.


Martin Lee, 2010/07/21 17:58

Dear Ram,

Thank you for the “Spread Spectrum Cap Sensor” tutorial and test results. I am currently working on measuring the distance of a sensor to an optical surface coated with aluminum and looking for the distance it moves. The move size is less than 2 um (2×10^6 meters) and the requested resolution is < +/- 1 nm (1x 10^9 meters). Would you like me to pass some information to my client (boss)?

Martin Lee Phone: +1 408 898 4095 Site:

Martin Lee, 2010/07/21 18:02

I made an omission,

“2 um (2×10^6 meters)” should be “2 um (2×10^-6 meters)”

”< +/- 1 nm (1x 10^9 meters)” should be ”< +/- 1 nm (1x 10^-9 meters)”

Sorry, Martin Lee

Robert MacLachlan, 2010/07/28 21:33

I know that capacitive sensors are often used for nanoscale measurement, and a dynamic range of 1:2000 doesn't seem unreasonable. I mostly recommend the Analog Devices capacitance-to-digital converter product line. They are higher performance than your typical touch-sensor chip, intended for instrumentation applications.

Physik Instrumente also makes off-the-shelf sensors for nano-measurement applications:

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wiki/user/ram/electro/0main.txt · Last modified: 2010/05/31 15:31 by ram