Fast Steering Mirrors 101: A Guide To The FSM Systems

Posted on: 15 September 2017

A fast steering mirror is a mirror that is mounted on a support system that can be tilted towards a light source such as a laser beam. The motion of the mirror is provided through actuators that are connected to the system. An open-loop and closed-loop operation are used by the fast steering mirror system. The loops use integrated sensors that offer high-speed precision for feedback control.

What are fast steering mirrors used for?

You may be surprised at all the different uses for fast steering mirror systems.

  • Tactical military hardware

  • Industrial instrumentation

  • Space telescopes

  • Aircraft infrared countermeasure systems

  • Tracking or scanning sight stabilization

  • Missile defense programs

Why are they so effective?

The way that the light is reflected completely eliminates "jitter," which is caused by 3-D mechanical vibrations. This happens when the various 3D objects change rapidly and the flow fields can't compensate quickly enough. The result leaves a less-than-desired effect, like a blur. The fast steering mirror uses light which does not have an appreciable momentum. Therefore, the beam can be stabilized to microradians. That gets rid of image blurring and jitter. The system can be altered and driven out to various tilt wavelengths at frequencies over one kilohertz.

What are the advantages to using this system?

Other than the removal of jitter and blur as mentioned above, there are several other advantages to choosing a fast mirror system:

  • High resolution up to nanoradian range

  • Parallel kinematics design due to the coplanar motion from a multiaxis

  • Long travel ranges up to six degrees of deflection

  • Fast response time up to a sub-millisecond

  • One pivot point

  • No polarization from rotation

  • Faster when compared to other systems, like galvo scanners


If you want to implement fast steering mirror systems in your projects, you can choose from a lot of different choices: phase shifters, miniature piezo tilts, pitch and roll motion mirrors, high-speed piezo tilts, compact piezo tips, and positioners with aperture.

There are several different models and brands of fast steering mirrors that you can choose from. It all depends on your preferences, budget, and what need the fast steering mirrors must meet. Just like any other technology, you know what you like best. Not sure where to start? Try looking for recommendations or browse through some online reviews to see what other users have tried and preferred. You can even join forums to ask others about their personal experience with the systems.