Precision Actuators in Astronomy Applications

High resolution actuators in astronomy applications are especially critical for large telescopes with segmented mirrors. All mirror segments need to be aligned to within nanometer tolerances to avoid distortion. PI provides a number of different drive concepts, including servo and stepper motor driven precision screw actuators, piezo motor actuators, and high-end hybrid actuator designs. Hybrid actuators combine low dynamic, long range and high dynamics, ultra-high precision components into one integrated actuator using one common nanometer-precision position feedback sensor.   

Hybrid Nano-Precision Actuators for ELT

PI wins Contract for more than 2000 actuators for the 798 quarter-ton segments

  • 1kN Force
  • 2nm Tracking accuracy

LAMOST  Telescope, China

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope

  • The light from 4000 celestial objects will be led into a number of spectrographs simultaneously
  • MA:  24 plane segments
  • MB : 37 spherical segments
  • PI supplied 200 Custom Stepper Actuators for Primary Mirror Segment Alignment



  • Stroke: 4mm  
  • Push/pull force: 400N 
  • Resolution: 4.45nm  
  • Min. step size: 15nm  
  • Max. velocity: 9μm/s  



  • Stroke: 25mm  
  • Push/pull force: 300N  
  • Resolution: 11nm  
  • Min. step size: 30nm  
  • Max. velocity: 17μm/s 

SALT 10m Telescope, South Africa

PI supplies custom M-235 actuators for primary mirror segment actuation

  • 273 actuators, 3 per mirror segment including controllers
  • Similar Design as M-235.2DG
    • Travel: ± 10mm
    • MIM: 0.1µm
    • Backlash:1µm
    • Push/pull force: 120N
    • Stiffness axial: 10^6N/m
    • Velocity: 3mm/s
    • Position feed-back: optical encoder

More Reading