Optical Engineer Explains How to Clean LIGO's Unique Optics

To search for gravitational waves, the Laser Interferometer Gravitational-wave Observatory (LIGO) uses a laser beam that is split in two and travels down perpendicular 2.5-mile arms containing mirrors at their far ends. The beam reflects off the mirrors and bounces back to converge where the arms meet. A passing gravitational wave will stretch and squeeze space itself, causing the distance a light beam travels to increase or decrease ever so slightly and this changes the way the split beams ultimately converge. But if any component has so much as a piece of dust on it, it might contaminate LIGO's optics and diminish the signal of a gravitational wave. Advanced LIGO Senior Optical Engineer GariLynn Billingsley at Caltech  describes the work she does to characterize and clean the optics that go into LIGO.