Theoretical And Experimental Studies Of Light Scattering From The Random Surface Based On Equal Vertical Wave Vector

Light scattering is one of the powerful tools for characterization of rough surfaces. Sincethe measurement is simple and is feasible in hostile environments, light scattering has foundwide applications in various fields such as the growth fronts monitoring, detections offabricated optical elements, analysis of the fractured cross-section of materials. Usually,rough surfaces have the characteristics of fractality, and they are verified to influence greatlythe scattered intensity distributions. In the past decades, the experimental extractions of roughsurface parameters including the fractal factor, and the traditional roughness and correlationlength, have attracted great interests. With the development and improvement of the selfaffine fractal surface model theory and light scattering experimental measurement,variousmeasurements method of random rough surface sample parameters have been mentioned.Lighting scattering experiment measuring isotropic in most widely used on the surfacemeasurement method. Zhao et al. developed the systematical experimental methods with theangle-resolved in-plane light scattering schemes. In the angle-resolved scattering experiments,the intensity profiles are measured at different perpendicular wave vector componentk values of the wave vector by changing the incident angles. From these profiles, theparameters of the rough surfaces including that describing the fractal dimension of the surfaceare extracted. So far, in the literature the light scattering measurements are conducted mainlyby moving the detector in a vertical straight line segment centered at the specular reflectionpoint. In this case, the value of perpendicular wave vector componentk can not maintainconstant, which may bring about possible errors in the measurements. For more preciseperformance, the detector needs to move along a specified circular arc segment to assure aconstantk in the measurement, which usually complicates the design of the setups. Atpresent, the scattered intensity patterns may be obtained very easily due to the common use ofcharge coupled device (CCD), and this brings about possibility of the substitution of CCD for the single detector in the scattering experiments. What is more important is that at certainangle of incidence, the perpendicular wave vector componentk varies with the scatteringpolar angle, and then the intensity profiles with different constant values ofk may beextracted from the single intensity pattern. In this paper, we propose the experimental methodto realize the consideration.This paper has reported that measuring the roughness of randomrough surface by using the resolution experimental method.In this paper, we first introduced the rough surface morphology characteristics and themethod of measurement. Then we introduced the theory of light scattering on the roughsurface and measured parameters of two samples by AFM. In the end, we propose theexperimental method to realize the consideration. In the experiment, an image of scatteredintensity distribution is taken at certain incident angle of illuminating beam. For an intensityprofile of constantk to be obtained, the data of those CCD pixels are read that lie on aspecific curve corresponding to a fixed scattering polar angle but varied azimuth angle. Bychanging the scattering polar angles, we obtain profiles with differentk values. Using theprofiles, the variation of their full-width at half-maximum (FWHM) versusk is acquired.From the FWHMs, we extract the roughness factor of rough surface samples. Two roughsilicon wafers are used as the samples for the light scattering measurement, and the extractedvalues of roughness, lateral correlation length and fractal exponent are in accordance withthose measured by atomic force microscope (AFM). The work of this paper for the first timeuses a single scattering pattern image to acquire profiles of different constant values ofk,which makes full use of the scattering image and greatly simplifies rough surfacecharacterization with light scattering experiment, which provide the theoretical basis for thedevelopment of light scattering experiment.