Abstract

We present theoretical and experimental results for the backscattered intensity from a roughened metallic disk tilted at an arbitrary angle to the incident illumination. As the rms roughness is increased from 1 to 10 µm the zero-tilt intensity decreases by >1000 but at a 75° tilt it is shown to increase by >100. We also investigate the decor-relation of speckle with wavelength at various tilt angles. Tilting the surface to the illumination and then observing the intensity pattern in the specular direction gives a means of characterizing the roughness parameters. In performing the calculation the effect of shadowing must be included. We analyze this effect by comparing the calculated results with shadowing to those without shadowing. The effect becomes significant for moderate tilt angles (>60°) and large roughness. In addition we review recent developments in enhanced backscatter as applied to rough surfaces. Several techniques for producing the roughened surfaces are also described including beadblasting, photolithography/ion-etching, and exposing the photoresist to controlled speckle patterns. These techniques give us the ability to produce surfaces with rms roughnesses ranging from 1 to 10 µm and correlation lengths from 1 to 50 µm.

© 1991 Optical Society of America