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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.
wiki/user/ram/electro/0main.txt · Last modified: 2010/05/31 15:31 by ram
Discussion
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: USStepper.com
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
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. http://www.analog.com/en/analog-to-digital-converters/capacitance-to-digital-converters/products/index.html
Physik Instrumente also makes off-the-shelf sensors for nano-measurement applications: http://www.physikinstrumente.com/en/products/capacitive_sensor/index.php