OBSERVATION OF GIANT ENHANCED BACKSCATTERING OF LIGHT FROM WEAKLY ROUGH DIELECTRIC FILMS ON REFLECTING METAL SUBSTRATES

The enhanced backscattering of light from a randomly rough surface, wh ich is manifested as a narrow peak in the retroreflection direction in the angular distribution of the intensity of the light that is scatte red diffusely, has been extensively studied. Both theoretical and expe rimental investigations have shown that the height of the peak is neve r more than twice the height of the background at the position of the peak. We report the observation of a giant enhanced backscattering of light from a randomly weak rough dielectric film on a reflecting metal substrate, in which the ratio of the height of the peak to the height of the background at its position is greater than 10. It is found tha t this giant enhanced backscattering peak is accompanied by concentric circular interference fringes, whose axis is normal to the mean scatt ering surface, with both the specular and backscattering peak on the s ame ring. A possible mechanism for the giant backscattering is suggest ed. (C) 1996 Society of Photo-Optical Instrumentation Engineers.