µARC – Angle and Device Measurement System

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 is 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 ABRT400 – 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 ABRT400 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 or Automation1 motion control platform. 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.