Metrology of Segmented Clear Apertures

Mike Zecchino

Dynamic interferometers are used throughout the world for making critical measurements of large mirrors, telescopes and other optical systems. The combination of application-specific analysis software and vibration-insensitive measurement hardware makes it possible to measure optical systems with segmented clear apertures.


Laser interferometry is a widely established method for measuring the shape and surface quality of large telescope mirrors. In recent years, the advent of dynamic interferometry—in which all data about the optical surface is acquired simultaneously rather than sequentially—has made these measurements considerably easier to implement. Because of their extremely short acquisition time, dynamic interferometers are insensitive to vibration and air turbulence and thus able to measure mirrors from tens of meters away in test setups. Most major telescope projects now use dynamic interferometry to test their optical elements.

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