Long Path Measurements

To measure the entire optical surface of a large optic, or an element with a long radius of curvature, the measurement system may need to be positioned far from the test piece—in some cases tens of meters away. Such a large cavity between the test and reference optics will almost inevitably lead to vibration and air turbulence that will significantly distort the measurement data.  Large scale airflow and temperature control systems can be prohibitively expensive or impractical over long measurement paths. Vibration is difficult to isolate in long path test setups as well.

4D’s PhaseCam dynamic laser interferometers are used by the world’s premier large optics manufacturers and telescope integrators to ensure excellent performance after installation. Their ability to measure optics despite vibration and to thrive in environments with significant turbulence makes PhaseCam laser interferometers perfectly adapted to long stand-off measurements without vibration isolation.