Keywords

Aluminum Fluoride, index of refraction, ultra violet spectrum

Abstract

A NASA project called Large UV/Optical/Infrared Surveyor (LUVOIR) is looking into ways to coat a mirror for a new space telescope. We contributed to this project by investigating aluminum fluoride (AlF₃) as a possible coating for the mirror. We measured the index of refraction of AlF₃ in the wavelength range 6 – 49.5 nm by testing three sample mirrors, each made up of a silicon wafer with a coating of AlF₃. We took data at the Advanced Light Source (ALS) in Berkeley, California and in the laboratory at Brigham Young University (BYU). There are discrepancies between the measurements from ALS and BYU. The cause of these differences is still unknown, but we have concluded the ALS measurements are more reliable. The optical constants found at the ALS agree with index of refraction data taken from The Center for X-Ray Optics (CXRO) for AlF₃.