Angle and Rotary Device Calibrator – µARC


Design Features

  • Master-axis accuracy: <0.6 microradian (<0.12 arc-second)
  • Minimum incremental step: 0.035 microradian (0.007 arc-second)
  • Angular measurement uncertainty: <0.73 microradian, k=2 (<0.15 arc-second expanded uncertainty, k=2)

Aerotech’s Angle and Rotary Calibration system, the µARC, sets a new industry standard of performance for angle and rotary device calibrations requiring long-term stability and angular accuracy of <1 microradian (0.2 arc-second).

The system was designed for applications requiring ultra-precision measurement capability with step sizes ranging from less than 0.1 microradian to continuous rotation. Applications include calibration of angle encoders, sensors, indexing tables, polygons and optical prisms. Electro-optic imaging sensors such as IR cameras, satellite imagers and spectrometers can be rotated on this device relative to a collimated target to test sensor properties such as field of view, pixel resolution and lens distortion.

The entire instrument is built on a precision granite machine structure that is isolated from the machine base and floor through passive air isolation. A custom enclosure isolates the system from air turbulence, high-frequency thermal fluctuations and ambient light. System electronics are packaged in a way to keep heat and electrical noise away from the sensitive measurement areas.

Air-Bearing Rotary Master Axis

At the heart of the µARC system is the ABRT-400 – a large rotary air-bearing axis with nanometer-level error motion performance. This high-accuracy air-bearing master axis is constructed of steel to closely match the CTE of the surrounding granite structure. The air bearing is equipped with a non-influencing rotary union and slip ring to pass vacuum or air and electrical service to the device under test. The ABRT-400 can be used as the angular standard in high-accuracy measuring machines, x-ray diffraction, protein crystallography or high-precision machining applications.


The µARC system is controlled by Aerotech’s A3200 motion controller. A customized menu-driven interface provides the user with easy control of the test procedure and plot/report generation, shifting focus to the performance of the Device-Under-Test (DUT) instead of machine operation. The system can be easily programmed to perform multiple unidirectional or bidirectional test cycles and can capture position data at rates up to 8 kHz during motion to correlate position or velocity versus a DUT output.


Angle and Rotary Device Calibrator Specifications

Accuracy 0.12 arc sec
Repeatability 0.08 arc sec
Axial Error Motion (Synchronous) <50 nm
Radial Error Motion (Synchronous) <75 nm
Tilt Error Motion (Synchronous) <0.1 arc sec
Axial Error Motion (Asynchronous) <10 nm
Radial Error Motion (Asynchronous) <10 nm
Tilt Error Motion (Asynchronous) 0.01 arc sec
Load Capacity Axial 200 kg
Load Capacity Radial 50 kg
Slip Ring Optional