Manipulating Dielectric Film to Give It a Refractive Index Close to Air (image) North Carolina State University Share Print E-Mail Caption By manipulating the structure of aluminum oxide, a dielectric material, researchers were able to improve its optical and mechanical properties. The key to the film's performance is the highly-ordered spacing of the pores, which gives it a more mechanically robust structure without impairing the refractive index. You can see the structure here, on the micrometer scale. Credit Chih-Hao Chang Usage Restrictions Image credit must be given. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.