Fast Steering Mirror Products (FSM Series) provides two-axis, high-bandwidth rotation with sub-microradian resolution using voice-coil technology. 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 suspension design to confine the motion of the mirror, it eliminates the bearing surfaces often used with galvanometer scanners, along with their associated stiction and wear. This results in ultra-smooth motion about the two axes intersecting at a common pivot point, very high accuracy, and practically infinite lifetime.
Newport offers a standard FSM-300 with a 1” (25.4mm) diameter mirror. A position transducer is included in the FSM mirror head to provide position feedback with reference to the support frame. A wide range of 1” mirror assemblies (mirror on carrier) for the FSM-300 Fast Steering Mirrors are offered. This allows the user to field replace the standard mirror with another mirror that best fits the specific application. The 1" mirror assemblies are sold separately.
For laser beam stabilization application, we recommend the OBP Series Laser Beam Position Sensing Detector.
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.
- Bode Plots for Typical FSM
- Typical Operating Area for FSM
Typical Specifications
|
Mirror Assembly |
FSM-300-01
|
| Number of Axes |
2 (tip-tilt) |
| Angular Range from ±10 V |
±26.2 mrad (±1.5°), Mechanical(1) |
| Resolution |
≤1 µrad rms, Mechanical(1) |
| Repeatability |
≤3 µrad rms, Mechanical(1) |
| Accuracy from ±26.2 mrad, 25°C(1) |
≤0.262 mrad (0.015°), Mechanical(1) |
| Linearity from ±26.2 mrad, 25°C(1) |
≤1.0% |
| Closed-Loop Amplitude Bandwidth for small signal inputs (-3 dB) |
600 Hz at 10 mV (typical) |
| Closed-Loop Phase Bandwidth (60° lag) |
250 Hz (typical) |
| Response Flatness(2) |
Peaking ≤3 dB |
| Noise Equivalent Angle |
≤3 µrad rms |
| Resolution of Local Position Sensor |
≤0.5 µrad |
| Operating Temperature Range |
0 to 50°C (32 to 122°F) |
| Storage Temperature Range |
-20 to 55°C (-4 to 131°F) |
| Sensor Warm-up Time for Mirror Stability at 25°C |
≤10 minutes |
| Mass |
1lb (0.45 kg) |
| Interconnect Cable Length |
9.8 ft (3 m) |
| Dialectric Mirror Substrate Material |
Pyrex |
| Mirror Retaining Mechanism |
Mirror bonded to aluminum carrier, field replaceable |
| Pivot Point of Axes (centered on mirror) |
12.19 mm behind mirror surface |
| Mirror Diameter |
25.4 mm |
| Mirror Thickness |
6.0 mm |
| Mirror Wedge |
≤5 arc min |
| Clear Aperture (at 0° angle of incidence) |
≥20.3 mm |
| Clear Aperture (at 45° angle of incidence) |
≥14.4 mm |
| Reflectivity(2) |
Enhanced Aluminum: >93%, 450-700 nm
Protected Gold: >96%, 650-1700 nm; >98%, 1.7-2.0 µm |
| Surface Flatness(2) (after coating and bonding) |
≤λ/8 at 632.8 nm over clear aperture |
| Surface Quality(2) |
15-5 scratch-dig |
1) Optical angular range is equal to twice the mechanical angular range.
2) Optical parameters apply to central 80% of mirror aperture.
| Controller/Driver |
| Command Input and Position Output |
Analog, ±10 V = ±26.2 mrad |
| Peak Operating Power to Mirror |
30 W |
| Continuous Maximum Operating Power to Mirror |
15 W |
| Thermal Protection |
60°C at mirror coil |
| Current Protection |
3 A |
| Operating Temperature Range |
0 to 50°C (32 to 122°F) |
| Storage Temperature Range |
-20 to 55°C (-4 to 131°F) |
| Power |
100-240 Vac ±10%, 47-63 Hz |
| Mass |
5.45 lb (2.5 kg) |
| Envelope [w x h x d] |
9 x 3.45 x 10 in. (229 x 88 x 254 mm) |
Note: Performance data is based upon well-defined, smooth, D-A sine wave inputs. Contact Newport regarding alternate inputs (square waves, triangle waves, low resolution D-A sine waves), which may adversely effect system performance.
Typical Operating Area for FSM
