Deformation and shape measurement using multiple wavelength microscopic TV holography

Abstract

Characterization of deformation and surface shape is an important parameter in quality testing of micro-objects in view of the functionality, reliability, and integrity of the components. Single-wavelength TV holography is widely used for deformation analysis. However, the single-wavelength TV holographic configuration suffers from overcrowding of fringes for large deformation that sets a limitation due to speckle decorrelation for quantitative fringe analysis. Furthermore, shape cannot be determined when using single wavelength. In this paper, we describe a multiple-wavelength microscopic TV holographic configuration that uses sequentially recorded phase-shifted frames at three different wavelengths before and after deformation of the specimen for evaluation of relatively large deformation fields at the effective wavelengths. Use of multiple wavelengths for deformation and shape evaluation is discussed. The design of the system along with the experimental results on small-scale rough specimens under static load is presented.