Rugate filter made with composite thin films by ion-beam sputtering

Composite films of Ta-Si oxide with refractive indices that varied from 1.48 to 2.15 were realized by using rf ion-beam sputtering. All the composite films were amorphous and had a surface roughness of less than 0.3 nm. The inhomogeneity of the composite was discussed, and a rugate filter was designed and fabricated by automatic computer control.