Aidan Brooks
PMA
Stephen Appert
PMA
GariLynn Billingsley
PMA

A microscopic section of one the 40kg optics present in the LIGO Livingston gravitational wave detector (ETM-Y) when the first gravitational wave event from a binary black hole merger, GW150914, was observed on September 14th, 2015. This image is approximately 125 microns in width and shows microscopic damage to the high-reflectivity coating on that optic. The image was acquired by illuminating the optic with white light, photographing it under a microscope and compositing multiple frames together. The transmission/reflection spectra of the coating vary with wavelength due to its multi-layer construction. Damage from an unknown cause has resulted in layers of the coating flaking off, varying the transmission spectrum and, hence, the observed color in different regions. Original photography by Stephen Appert and GariLynn Billingsley.

brooks_a@ligo.caltech.edu