Three years ago news form the first detection of gravitational wave echoed around the world. And in August 2017 a gravitational wave signal for the first time informed us about the location of a cosmic explosion before we had seen a single photon from the event. The machines that made all this possible are the two interferometers of the  Advanced Laser Interferometer Gravitational-Wave Observatory.  They truly are a marvel of precision metrology.

 Since August 2017 the interferometers underwent numerous fixes and upgrades, with the goal of commencing most far-reaching observation run in Spring 2019.

I will take you behind the curtain, under the clean room enclosure and inside the vacuum chamber of the machines. We will look at what makes the extraordinary sensitivity of those detectors possible and discuss the challenges that currently limit their performance.