Electromagnetically Driven Ultra Fast Motors


Manufacturing complicated free formsurfaces for industrial applications include:

  • Optical tracking and pointing systems with fine steering mirrors
  • Active and adpotive optics in laser systems and large telescopes
  • Engravers for cutting printing plates
  • Fast tool servos (FTS)

Problem Addressed

Increasingly complex free form surfaces are being used in industry. An example of this is the manufacture of nanometer-scaled resolution free form surfaces and films for brightness enhancement and controlled reflectivity, sinewave ring mirrors used in CO2-laser resonators, molds for contact lenses, and micro-optical devices such as Fresnel lenses, multi-focal lenses and microlens arrays. One method of realizing these designs is the use of fast tool servos (FTS), which are high bandwidth positioning devices that can produce free form surfaces with nanometer-scale resolution in conjunction with an ultra-precision lathe and diamond tooling. A consequence of increasing the design complexity is that surfaces require more components to be in shorter spatial wavelengths. This requires advanced FTS designs which have high bandwidth, high acceleration and high accuracy.


The invention is an ultra-fast motor with an associated controlling mechanism to achieve higher acceleration, accuracy, and bandwidth than previous FTS systems. The system has a bandwidth of over 20 kHz and greater than 1000G acceleration, while maintaining nanometer resolution. In addition, a power amplifier was designed for driving the high bandwidth ultra-fast motors, a real time computer architecture was designed for controlling the FTS capable of over 1 million samples per second, an integration method for integrating the ultra-fast FTS into commercial diamond turning machines was developed, and a collection of direct sensing and manufacturing methods were developed to enable efficient high acceleration, accuracy and bandwidth nanoscale featured surface generation.


  • >20 kHz bandwidth FTS control, >1000G acceleration, nanometer-scale resolution
  • Improved linearity
  • Improved acceleration due to full armature surface area usage in generating actuation
  • More actuating force generated without overheating coils or saturating solenoid flux path