Helping to Prove the Existence of Gravitational Waves
Challenge
Since 1916, the existence of gravitational waves has been predicted. However, even Albert Einstein never dreamed that such phenomenally small events could actually be observed and measured. Nearly a century later, in 2002, the Laser Interferometer Gravitational-wave Observatory (LIGO) started looking for these distortions in the fabric of space-time. But nearly a decade of diligent engineering yielded no results. The kilometers-long Michelson interferometer should have been sensitive enough to measure the most cataclysmic events in the cosmos. Yet, system noise was an ever-present and obscuring issue.
Solution
One major problem was thermal lensing of the collimating optics. The intensity of the interferometer probe beam needed to maintain coherence in order to provide the incredibly sensitive interference fringes from which a successful measurement could be made. Access Laser’s contribution was providing an ultra-stable light source to counteract the slight temperature gradient across the surface of the lens. Our 50W laser, with stability-enhancing technologies, was integrated during facility upgrades at both EIGO and LIGO Advanced.
Results
After installing the L50-ST-WCCL from Access Laser, along with a series of other improvements, the Advanced LIGO project resumed operation in 2014. Just days after turning on the new and improved facility, an observation was made with six sigma certainty. This provided confidence that the event proved the existence of gravitational waves to a probability of greater than 1 in 26,330,254. This was a great moment in the history of human ingenuity, confirming a radical theory through inspirational engineering. The true moment of triumph for Access Laser founder Dr Yong Zhang came two days before the official announcement, however, when he received a personal call to inform him of this pivotal achievement.
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