Plate Nº 33 · recorded October 10, 2026
Space & AstronomyReported finding
ANU's Atom-Precise Coatings Will Sharpen LIGO's Gravitational Wave Hunt
After three years of work, ANU researchers coated two LIGO beamsplitters to within 1–2 nanometers across nearly half a meter — a precision of just a few atoms from edge to edge.
By Marcus Bennett3 min read550 words
In brief
- ANU spent 3 years developing two beamsplitter coatings precise to within 1–2 nanometers across nearly half a meter
- Each beamsplitter is a 45 cm glass disk weighing more than 20 kg, made from some of the purest glass in the world
- ANU is one of only two groups worldwide capable of producing LIGO-grade beamsplitter coatings
- Scientists first detected gravitational waves directly in 2015, a century after Einstein predicted them
- The team built 8 custom automated systems to clean, measure, and handle the optics without human contact
After three years of work, ANU researchers have coated two LIGO beamsplitters to within 1–2 nanometers across nearly half a meter — a precision of just a few atoms from edge to edge.
The components head to LIGO (Laser Interferometer Gravitational-Wave Observatory), the global collaboration that first detected gravitational waves directly in 2015. Australia contributes through OzGrav, the ARC Center of Excellence for Gravitational Wave Discovery.
What did the team actually build?
The two beamsplitters are 45-centimeter (18-inch) glass disks weighing more than 20 kilograms (44 pounds) each, made from some of the purest glass in the world. Each disk carries two custom coatings:
- A front coating that splits a laser beam precisely in half
- A back coating with ultralow reflectivity — more than 1,000 times more effective than a standard eyeglass lens coating
LIGO uses the beamsplitters inside its giant interferometers. A passing gravitational wave stretches and squeezes space by a tiny amount, changing how the split beams travel and recombine. The detector must spot distance shifts around a millionth of a billionth the width of a human hair.
Why does the precision matter so much?
Robert Ward, a professor and director of ANU's Center for Gravitational Astrophysics, said the project pushed precision optics into new territory.
"You need exquisite measurement precision, very tightly controlled processes and extreme coating thickness uniformity to build these components," Ward said. "We're coating this glass to within a nanometer or two across almost half a meter — a few atoms' difference from one edge to the other."
How did ANU reach that level?
Steve Madden, a professor at ANU's Research School of Physics and director of the Australian National Fabrication Facility's OptoFab ACT Hub, led the effort.
"We spent three years on very challenging research and development and put our heart and soul into building these optics," Madden said. "We really want to see this Australian contribution produce great results for international science."
No off-the-shelf equipment could meet the requirements. The team built eight custom automated systems to clean, measure, and handle the optics without human contact. Deon Hickey from ANFF OptoFab ACT said the constraints forced entirely new approaches.
"Every component that goes into this detector is pushed to the absolute limit," Hickey said. "There aren't many machines in the world that can meet the requirements, so we had to build our own equipment and find new ways to solve the problems."
The work took place inside ANU's new Research School of Physics Clean Room, where cleanliness standards matched those of advanced semiconductor fabrication facilities.
What does this mean for gravitational wave science?
ANU is one of only two groups worldwide that can produce beamsplitter coatings to LIGO's standard. The upgrade should help LIGO pick up more events, including weaker signals from farther away, and study colliding black holes and neutron stars in greater detail.
Albert Einstein first predicted gravitational waves more than a century ago — tiny ripples in space-time from some of the universe's most powerful events. Scientists first detected them directly in 2015, opening a new way of studying the cosmos.
The new coatings are part of an ongoing upgrade cycle. Researchers expect to refine the techniques further as LIGO moves toward its next phase of sensitivity.
via Phys.org Space & Astronomy (Source)
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