Gravitational-wave astronomy, one of the newest and most exciting fields in science, may soon take a major step forward thanks to a breakthrough in optical technology.
A team led by Jonathan Richardson, a physicist at the University of California, Riverside, has developed a system called FROSTI that promises to make gravitational-wave detectors like LIGO more precise than ever before.
Their work, described in the journal Optica, could help usher in the next generation of observatories.
Gravitational waves are ripples in spacetime, produced when massive objects such as black holes or neutron stars collide.
Their discovery by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2015 confirmed a prediction of Einstein’s Theory of Relativity and opened a brand-new way of observing the universe.
LIGO detects these faint signals using two enormous interferometers in Washington and Louisiana, each four kilometers long.
The sensitivity of LIGO is staggering. Its mirrors must remain still enough to detect distortions smaller than a thousandth of the diameter of a proton.
But such extreme precision comes with challenges.
Environmental vibrations, heat, and even the lasers themselves can distort the mirrors, masking the faint signals scientists are trying to detect.
That’s where FROSTI—short for FROnt Surface Type Irradiator—comes in. Unlike current systems, which can only make rough corrections, FROSTI can make extremely precise, high-order adjustments to the mirrors.
It works by projecting carefully controlled heat patterns onto the mirror’s surface.
This might sound counterintuitive, but the targeted heating restores the mirrors to their correct optical shape, smoothing out distortions without adding noise that could be mistaken for a gravitational wave.
“FROSTI is designed to reshape LIGO’s mirrors while handling laser powers above one megawatt, which is billions of times stronger than a laser pointer and nearly five times higher than what LIGO uses today,” said Richardson. “It’s a crucial step for the future of gravitational-wave astronomy and for next-generation detectors like Cosmic Explorer.”
Boosting the laser power is one of the most important ways to improve sensitivity in gravitational-wave detectors. The problem is that higher power often damages the delicate quantum states used to sharpen the signals.
FROSTI solves this issue by ensuring that the mirrors stay undistorted even under extreme conditions.
The result could be a tenfold improvement in how far into the universe scientists can peer, potentially allowing the detection of millions of black hole and neutron star mergers across cosmic history.
The new system was successfully tested on a full-scale 40-kilogram LIGO mirror.
Future versions will be adapted for the massive 440-kilogram mirrors envisioned for Cosmic Explorer, a planned observatory that will be far more powerful than today’s LIGO. FROSTI will also play a key role in LIGO A#, an upcoming upgrade that serves as a stepping stone to the next generation.
“The current prototype is just the beginning,” Richardson said.
“We are already designing improved versions capable of handling more complex optical distortions. This is the research foundation for the next 20 years of gravitational-wave astronomy.”
With FROSTI, researchers believe gravitational-wave observatories will not only continue to confirm Einstein’s theories but also open a clearer and deeper window into the hidden dramas of the universe—colliding stars, merging black holes, and perhaps phenomena we have yet to imagine.
