European Space Agency

LEOCAT - Optical Communication Optical Head


Design and testing of a low SWaP optical head for optical communication


Design of a high performance optical head for low recurring cost of series production. 


  • Low recurring cost
  • Compact, highly integrated design (low SWaP)
  • Low WFE design and manufacturing/assembly strategy
  • Low pointing error due to high bandwidth fine steering mirror, point-ahead mirror and Tx/Rx calibration strategy. 


  • 10 Gbit/s Intersatellite optical link (@4400km)
  • Male-female configuration, assuming 4 terminals per satellite
  • 70mm aperture
  • Low volume
  • Low mass: <3kg
  • Low recurring cost
  • Operational temperature range: -20 ˚C +40 ˚C
  • Survival temperature range: -40 ˚C +60 ˚C
  • Pointing error Tx/Rx: <3urad RMS
  • WFE: 100nm RMS

System Architecture

  • Full metal 4 mirror telescope design followed by 4 channels (transmit, receive, acquisition, tracking)
  • InGaAs camera for acquisition and a quadrant detector for high speed tracking and control of the fine steering mirror.
  • Calibration function by having a second light source from the transmit fibre that can be back-reflected using a retro reflector to the tracking channel in order to correct the Tx/Rx co-alignment


Project kick-off was at 2018-09-06, final review at 2020-12-15

Current status

Project is finished

Status date

Friday, March 5, 2021 - 11:10