Automatic Full Strain Field Moiré Interferometry Measurement with Nano-scale Resolution

Abstract

Moiré Interferometry (MI) theoretically can provide real-time full strain field measurements in dynamic environment. So it's extensively used in reliability analysis of electronic packaging. Due to the nature of specimen preparations procedure, the optical noise is usually too strong so that an accurate phase-based information processing is not possible. In this paper, a 164 nm/pixel spatial resolution Moiré Interferometer with automated full strain field calculation is proposed. Provided by two-level zooming system, the high spatial resolution increase the signal intensity and eliminate some optical noise which allows accurate full strain field map generated automatically by the combination of phase shifting technique and continuous wavelet transform (CWT). Furthermore, the calculation procedure of CWT proposed here does not require unwrapping and differentiation, which avoid the possible numerical noise introduced in these two steps. In the proposed system, pixel by pixel in-plane strain tensors will be calculate from the intensity map of interferograms using phase-based method. The resulting strain tensor can be used to model constitutive relationship or compare with finite element analysis results. A thermal experiment on BGA packaging is used to demonstrate the advantages of the proposed new design.

Parameter estimation of optical fringes with quadratic phase using the fractional Fourier transform

“…This method is error-prone because the Contents lists available at ScienceDirect procedure requires phase unwrapping and numerical differentiation operations [7]. Several optical techniques have been proposed to directly measure the phase derivatives [8][9][10]. The measurement depends on the physical setup of a particular method and cannot be generalized.…”

Out-of-plane displacement field measurement by shearography

“…In general, triangulation methods such as speckle projection [1] and fringe projection [2,3] provide large and flexible measurement ranges depending on the hardware setup. However, interferometric methods including holographic interferometry [4,5], shearography [6][7][8], speckle interferometry [9][10][11], and moiré interferometry [12,13] are more suitable for microscale and nanoscale measurements since they provide considerably higher accuracy.…”

Displacement and Strain Measurement by Circular and Radial Gratings Moiré Method

“…This geometric moiré method has such advantages as non-contact, full-field and real-time, etc [1]. With the development of computer technology, Asundi, et al [2,3] proposed digital moiré method and adopted phase shifting technique to quantify fringe information, and many researchers have done some works on logical moiré and phase shifting technique [4][5][6][7][8]. Compared with geometric moiré method, digital moiré method provides digital fringes through logical operations on computer-generated reference grating images and deformed grating images acquired in real time, and phase shifting technique is adopted to extract deformation information from fringes.…”