Fine steering mirror


Laser communication is considered a key enabler for future high data communications between satellites, aerial vehicles, and ground stations. For successful laser communication over several thousands of kilometers distance, pointing of the laser beam between the transmitter and the receiver needs to be controlled with a precision down to a few microradians.

The FSM product is specially designed for laser communication to enable this level of precision pointing.  


  • Technology developed by DEMCON with TNO
  • Space-compatible
    • Compact
    • High compensation bandwidth with fast dynamical response
  • Specifically developed electromagnetic actuator
    • Enables high efficiency in terms of volume and unit power
    • Optionally redundant
  • Flexural bearing yielding high linearity and no wear
  • Customized mirrors up to 30 mm diameter possible.
    • Standard 20mm mirror with flatness < 12nm RMS
    • Broadband coated
    • >95% reflection over broad wavelength range
  • Optional: Angular feedback control by utilizing angular displacement sensors to measure and control the mirror angle with high accuracy
  • Scalable to different sizes

How it works

Within a laser communication terminal, a tracking sensor controls the pointing. The sensor measures the incoming angle of the received light from the partnering terminal. Based on these readings, a Coarse Pointing Assembly (CPA) together with the FSM correct high-frequency misalignments. In addition, a second FSM provides information on the Point Ahead Angle (PAA), enabling the laser communication terminal to compensate for the “time of flight” – or the time it takes for the laser beam to arrive at the receiving end.

The FSM is a versatile product. Although in its essence a fast-tip tilt mirror, it can also be used in other applications.

Point of contact

Marko van Dalfsen