[VIDEO] TMT Metrology Testbed CGH Phase Fiducial Alignment

Aligning a 1.5 m diameter mirror segment to an interferometer 13 m away, to an accuracy of 25 microns. How is this done? Computer Generated Holograms are the solution! In this video, Dr. Shelby Ament describes the concept of “CGH Phase Fiducials”, used in a Metrology Testbed for the Thirty Meter Telescope. These alignment CGHs, as well as the main CGHs used to measure the segments, were designed and fabricated by Arizona Optical Metrology LLC.

This excerpt is from a talk titled “Metrology Testbed for the Thirty Meter Telescope Primary Mirror” from the Optical Fabrication and Testing Conference on June 13, 2021. Content is shared with permission from the OSA.

Shelby Ament, Ph.D., is a senior optical engineer at Arizona Optical Metrology (AOM). She holds a doctorate from the University of Arizona’s Wyant College of Optical Sciences, with specialization in diffractive optics. She has five years of industry experience designing, fabricating, and using CGHs to test a variety of optics: from catalog cylinders and aspheres to meter-class telescope mirrors. At AOM, she designs and certifies CGHs for customers and develops next-generation metrology products.