Effects of surface microstructure on macroscopic image shading
Duje Tadin, Richard F. Haglund, Joseph S. Lappin, Richard Alan Peters · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2001
The reflectance characteristics of materials are known to have visible effects on image shading functions. The present study quantified the light scattering distributions form roughened glass and correlated these with the microscopic surface topography. Samples were 11 silica microscope slides, roughened with commercial diamond pastes with particle sizes ranging from 4-67 m. In-plane and out-of- plane scattering measurements were made with laser light incident at 45 degrees. In-plane scattering distributions for samples illuminated with 633 nm varied significantly in their shape, but all curves were roughly centered on the specular angles. In-plane scattering distributions for 514 nm also disappearance of specular components was observed for samples whose RMS roughness just exceeded the wavelength of light. The results indicate that small changes in microscopic surface roughness can produce large changes in scattering. Evidently, surface microstructure has a pronounced effect on macroscopic appearance.