Optical Surface Roughness Determination Using Speckle Correlation Technique

Abstract

Two speckle patterns produced from the same rough surface by two different illuminations are correlated. The correlation depends on the surface roughness. The two illuminations were obtained here by varying the angle of incidence of a coherent plane wave on the surface. The speckle patterns are recorded on the same film by double exposure. By placing this film in a convergent laser beam, Young fringes are observed in the Fourier plane. The correlation of the speckle patterns is obtained by measuring the visibility of the fringes. The theoretical calculations have been performed for a normally distributed surface. The experimental results are in good agreement with theory.

Non contact inspection of the fatigue damage state of carbon fiber reinforced polymer by optical surface roughness measurements

“…Roughness parameters have been selected to characterize the topography of the surface, because it is a property that can be measured precisely in the laboratory with nanometer resolution optieal perfilometers, such as confocal mieroscopes, and could be measured in the field by optieal techniques such as speckle ar partable optieal perfilometers [24][25][26][27].…”

Computation of surface roughness using optical correlation

“…In the speckle-correlation technique [28], a double-exposure speckle photography technique is used. The laser source has to be rotated between exposures and two speckle patterns are recorded on the same photographic film.…”

Angular correlation properties of 2D‐nano‐roughness‐induced speckle patterns for silica‐on‐silicon wafers

“…incident and scattering angles, is calculated through the degree of correlation between two speckle patterns. Such a technique was early used to assess surface roughness in the case of single scattering [3]. Feng et al [4] initiated considerable efforts in the prediction and observation of speckle correlation in the case of volume scattering [5], and then for scattering by rough surfaces [6].…”