ABSTRACT
We studied the surfaces of six precision-ground optical glass samples of fused silica, BK-7, BaCD16, LaC14, NbF1, and LHG8 glass, using a mechanical profiler, a photon tunneling microscope, and a scanning force microscope. The measured roughnesses of the scanning force microscope varied from 3.5 A rms for BK-7 glass to 30 A rms for LHG8 laser glass. Good agreement was obtained among the roughness values measured with all three instruments.
ABSTRACT
The roughnesses of five supersmooth dielectric films of Si(3)N(4), TiO(2), HfO(2), Ta(2)O(5), and Al(2)O(3) prepared by an ion-beam-sputtering technique were measured with a commercial Talystep mechanical profiler and a sensitive Leica WYKO SPM30 scanning force microscope (SFM) to determine how much roughness the films added to the â¼1-Å-rms roughness fused-silica substrates on which they were deposited. In all cases the increase in roughness for the three-quarter-wave optical thickness films was a small fraction of an angstrom. SFM measurements showed that the topography of the Ta(2)O(5) and Al(2)O(3) films was less random than that of the other film materials and the substrates.
ABSTRACT
The scanning force microscope (SFM) is used to study the characteristics of optical surfaces, such as polished and precision-machined surfaces and thin-film structures. Previously unreported images of raised surface scratches and clumpiness on the surface of extremely smooth dielectric films are presented. The characteristics of SFM's that are important in studying optical surfaces are discussed. They include the effects of tip geometry, surface charging, particulate contamination, scanner artifacts, and instrument calibration.
