Long Path Measurements

Measuring optical performance down to the smallest of measurements over extremely long distances, is no easy task. This is due to the unavoidable presence of air-turbulence and vibration.

4D Technology’s PhaseCam and AccuFiz product lines address the need for precise measurement under long pathlengths by effectively “freezing” the excess motion with nanometer resolution. Extended averaging techniques are then used to remove the errors from air-turbulence and achieve nanometer level resolution over meters of distance.

The James Webb Space Telescope (see Figure 1: James Webb Space Telescope – Long Path Testing) is a perfect example of how 4D Technology uses Long Path-Measurement to accurately measure all-around optical performance of a telescopic imaging system.

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.