4D Technology "dynamic" laser interferometers use proprietary, high speed, high resolution wavefront sensors to measure the shape of optical surfaces with extreme accuracy.
In a conventional phase-shifting laser interferometer, multiple frames of data are acquired over many milliseconds—enough time for vibration and turbulence to degrade the measurement results. In a dynamic interferometer, all phase data is acquired simultaneously, in as little as thirty microseconds. This speed enables 4D dynamic interferometers to measure in noisy environments, despite vibration solation or air turbulence.
Dynamic interferometry® enables complex tests between multiple unisolated tables, measurements in environmental chambers, and measurements with long stand-off distances. Odd shapes, pupil obscurations, poor signal contrast, moving parts, air turbulence and mechanical vibration are not problems. Special wavefront sensors have also been developed for wavelength insensitivity, higher spatial resolution, and applications within tight space restrictions.