Innovation and Partnerships Office

Positional Sensor Measures Rotational and Lateral Displacements IB-2328


Any device or product requiring highly precise movement and accurate measurement of an object’s position, including but not limited to:

  • Electron microscopes, to move specimens and measure their precise location
  • Next-generation storage media, such as holographic storage
  • Precision machine tools, such as tools that use lasers for laser ablation
  • Optical systems, such as position-sensing in a fiber optical switch


  • Measures both lateral and rotational (or angular) displacement
  • Space-efficient
  • Cost-effective


Berkeley Lab researcher Thomas Duden has invented a simple yet powerful positional sensor that can determine the position of an object to within a few nanometers. The new sensor provides information on both angular displacement and two-dimensional lateral displacement of moving objects, and can be used in any device requiring highly precise measurement of movement, such as electron microscopes and optical systems. The invention represents a breakthrough improvement over existing approaches, which provide measurements within the same degree of accuracy in only one or two dimensions within one sensor.

The invention uses opposing sets of capacitor plates (Fig. A) to measure an object’s displacement by measuring changes in capacitance as overlapping areas of the capacitor plates move. One set of plates is attached to a stationary object and another set of plates is attached to a moving object. The measurements are transmitted to a circuit that calculates angular and lateral displacement. For translational displacement, both moving capacitor plates are used for measurements (Fig. B), whereas for rotational displacement, individual measurements from the two rotational plates are compared (Fig. C). Depending on the selected electronic resolution, the system can calculate both the linear and angular displacement of one object relative to another (Fig. D) in a few tenths of a second, or faster, if less precision is selected for a dynamic approach.

This space-efficient and cost-effective sensor can be used in an electron microscope to measure and record the location of the specimen stage with respect to the electron beam. Locations of interest may also be stored, allowing the stage to return to that position at a later time. This feature may be particularly important for investigating crystalline structures.


STATUS: Published PCT application, WO2010/017065, is available at This technology is available for licensing or collaborative research.

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