Spectral analysis in resonant interferometry: following the traces of thermal deformation

How researchers from the LIGO scientific collaboration use signals generated from higher-order mode resonances to glean crucial information about the thermal state of their interferometers.

Chris Mueller

Chris Mueller received his Ph.D. in physics with Guido Mueller at the University of Florida and has since moved to industry.

Imagine for a moment that you’ve accepted the challenge of trying to make the first direct detection of gravitational waves. To achieve such a daunting task you’ll need to devise an instrument capable of measuring a change in length of just 10-19 m over a distance of several km. At these length scales everything matters; the ground is vibrating, air molecules are buzzing around, and the molecules which make up the test masses of your detector are quivering. This challenge is precisely Continue reading

Achieving resonance in the Advanced LIGO gravitational-wave interferometer

Alexa Staley

Alexa Staley is a PhD candidate at Columbia University in the City of New York, and has been working as a graduate student at the LIGO Hanford Observatory in Richland, WA.

The next generation gravitational wave interferometers, known as Advanced LIGO, located in Hanford, WA and Livingston, LA have been installed and are in the process of achieving a sensitivity required for the first direct detection of a gravitational wave. The goal of their design is to measure a gravitational strain as small as 4×10–24/√Hz, requiring a length resolution of approximately 10–19 rms within a 100 Hz bandwidth. This high sensitivity demands multiple optical cavities to enhance the response Continue reading