Measuring laser light scattering from an Advanced LIGO Viewport

The scattering lab at California State University Fullerton was designed to measure and image laser light scattering from optics to gain a better understanding of the mechanisms that lead to optical loss in gravitational-wave detectors. This poster describes and experiment conducted to characterize the light scattered from the front and back surfaces of a type of viewport, an anti-reflection coated window that allows laser beams to transmit into and out of the vacuum systems. These viewports are currently being used for Advanced LIGO. We present a description of our experimental setup, images of the light scattering off the viewport surface, measured scatter in terms of the Bidirectional Reflectance Distribution Function (BRDF) and Total Integrated Scatter (TIS).