The Influence of the Speckle Structure of the Scattered Laser Radiation on the Measurement Error of the Rough Surface Vibration Displacement
Abstract:
The influence of the speckle structure of the scattered laser radiation on the measurement error of the rough surface vibration displacementusing laser Doppler vibrometer assembled according to a differential scheme is studied. The scheme of the experimental setup for investigation of characteristics of laser beam reflected from different surfaces is described and the obtaineed experimental images are given. It is shown that the structure of a reflected and scattered beam highly dependent on parameters of roughness of an investigated surface. Based on the results of numerical simulation, characteristic dimensions of surface irregularities are obtained, at which the beam structure is destroyed and the speckle structure is formed. It is shown that in case of a partially developed speckle structure, the error will be determined by by the relative contribution of a mirror component, a contrast and an average intensity of a speckle field. To estimate the error, a numerical simulation was performed for given parameters of a surface, beam and scatterers.
Keywords:
speckle-structure, measurement of vibration displacement, laser radiation, vibrometry, measurement error
