LIMIT TO SENSITIVITY REDUCTION IN SHEARING SPECKLE INTERFEROMETRY IMPOSED BY IMAGING ABERRATIONS

Reduction in the amount of shear used in shearing speckle interferomte ry is desirable in applications where multiple wavelength measurements are required. The limit to this reduction, however, is determined by the statistical phase variance effect and imaging aberrations. Althoug h the latter effect has been mentioned, it has, hitherto, not been stu died in detail. In this paper, wavefront aberrations are simulated usi ng uniform deviate random number generators on the computer and the ad ditive noise analyzed at various nucleation, fluctuation, correlation length and shear levels. It is established that while larger nucleatio n, correlation length and fluctuation levels all contribute to an incr ease in the overall noise in the speckle image, only the correlation l ength imposes a limit on shear reduction in shearing speckle interfero metry.