Fast Steering Mirrors
Applications
  • Fast steering on a single pivot point for X and Y rotation
  • Steering mirror is suspended on a flexure, eliminating friction
  • Angular range ±3°, optical
  • Angular resolution ≤2 µrad rms, optical
  • Fast closed-loop control, to 800 Hz
  • Field replaceable 1 in. mirror assemblies
  • Larger angular range than piezo-driven mirrors
  • Eliminates displacement jitter found in dual XY galvo mirror systems
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DescriptionSpecifications Models Catalog PDF

Our Fast Steering Mirror (FSM) product offering provides two-axis, high-bandwidth rotation with sub-microradian resolution. Newport offers standard designs that are economically viable for widespread commercial use for applications such as laser beam stabilization, laser pointing, tracking, and image stabilization.

By utilizing a unique flexure design to confine the motion of the mirror, the bearing surfaces often used with galvanometer scanners are eliminated, along with their associated stiction and wear. This results in ultra-smooth motion, very high accuracy, and practically infinite lifetime.

Four voice coil actuators provide fast, high-bandwidth rotation. Utilized in push-pull pairs, the actuators provide smooth, even torque to the mirror. An internal optical-based feedback loop is built into the FSM-300 head to provide position feedback with reference to the support frame for accurate and stable pointing and tracking. When used in combination with Newport’s OBP Series Laser Beam Positioner, or a commercially available quad cell, an FSM can quickly lock to the detector for rapid laser beam control and stabilization.

The controller/driver establishes the feedback interface between the angle sensors and the drivers, providing current to the voice coils that tip and tilt the mirror assembly. It also provides a convenient interface between the user and the mirror, allowing control voltages to be applied and mirror position to be monitored. The controller/driver contains the control circuits, current drivers, universal power supply, and user interface. The updated FSM-CD300 Series Controller incorporates upgraded independent gain and DC offset adjustments of both X and Y-axes. This enhancement significantly improves the system performance for Laser Pointing applications, requiring accurately controlled point-to-point movements.

Fast Steering Mirrors offer a more compact package than dual XY galvometers. They eliminate the need to displace the beam to accommodate a second galvo or to compensate for polarization rotation due to an extra reflection. With higher optical performance than galvo scanners, FSMs have larger apertures, lower wavefront distortion, and a broader choice of mirror substrates and coatings. The rotational axes of an FSM intersect at a single pivot point, unlike dual XY galvos, eliminating the displacement jitter.

Newport offers a standard FSM-300 with a 1” (25.4mm) diameter mirror. A wide range of 1” mirror assemblies (mirror on carrier) for the FSM-300 are offered. This allows the user to field replace the standard mirror with another mirror that best fits the specific application. 1" mirror assemblies are sold separately.


FSM-300 Mirror Assembly


Rear View of Mirror Assembly


Front panel of the FSM-300 controller/driver.


Back view of the FSM-300 controller/driver.




  • Bode Plots for Typical FSM




  • Typical Operating Area for FSM