4 research outputs found
Material loss angles from direct measurements of broadband thermal noise
International audienceWe estimate the loss angles of the materials currently used in the highly reflective test-mass coatings of interferometric detectors of gravitational waves, namely Silica, Tantala, and Ti-doped Tantala, from direct measurement of coating thermal noise in an optical interferometer testbench, the Caltech TNI. We also present a simple predictive theory for the material properties of amorphous glassy oxide mixtures, which gives results in good agreement with our measurements on Ti-doped Tantala. Alternative measurement methods and results are reviewed, and some critical issues are discussed
Measurement of Thermal Noise in Multilayer Coatings with Optimized Layer Thickness
A standard quarter-wavelength multilayer optical coating will produce the
highest reflectivity for a given number of coating layers, but in general it
will not yield the lowest thermal noise for a prescribed reflectivity. Coatings
with the layer thicknesses optimized to minimize thermal noise could be useful
in future generation interferometric gravitational wave detectors where coating
thermal noise is expected to limit the sensitivity of the instrument. We
present the results of direct measurements of the thermal noise of a standard
quarter-wavelength coating and a low noise optimized coating. The measurements
indicate a reduction in thermal noise in line with modeling predictions.Comment: 8 pages, 14 figure
Material loss angles from direct measurements of broadband thermal noise
We estimate the loss angles of the materials currently used in the highly
reflective test-mass coatings of interferometric detectors of gravitational
waves, namely Silica, Tantala, and Ti-dop ed Tantala, from direct measurement
of coating thermal noise in an optical interferometer testbench, the Caltech
TNI. We also present a simple predictive theory for the material properties of
amorphous glassy oxide mixtures, which gives results in good agreement with our
measurements on Ti-doped Tantala. Alternative measure ment methods and results
are reviewed, and some critical issues are discussed