LIGO Document G0900581-v1

Transmission electron microscopy of mirror coatings for advanced and future gravitational wave detectors

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G - Presentations (eg Graphics)
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Advanced generations of ground-based gravitational wave detectors will use ultra-low-loss amorphous dielectric multilayer mirror coatings in order to minimize thermal noise, a limiting factor in detector sensitivity. Transmission electron microscopy is a promising way to probe the atomic structure of these coatings in an effort to better understand the causes of the observed mechanical loss (internal friction) and hence thermal noise.

Argon ion-sputtered amorphous Ta2O5 mirror coatings annealed at a range of temperatures have been studied using diffraction and spectroscopy in a transmission electron microscope to probe the short range atomic order, gain structural information on the form of the amorphous Ta2O5 and quantify the tantalum to oxygen ratios, which were observed to change with varying annealing temperature.

The results presented, combined with macroscopic measurements such as mechanical loss and direct density measurements of the coatings, provide a useful starting point for being able to understand and model the mechanisms underlying the thermal noise. Ultimately, this research will aid in the optimisation of coating materials to minimise thermal noise and consequently to improve the sensitivity of future detectors, thereby increasing the volume of the Universe that can be searched for gravitational waves.

Files in Document:
  • Poster (Amaldi Poster FINAL LIGO ID [Compatibility Mode].pdf, 2.6 MB)

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