Optimization of multiscale digital speckle patterns for multiscale deformation measurement using stereo-digital image correlation

Appl Opt. 2021 Jun 1;60(16):4680-4689. doi: 10.1364/AO.423350.

Abstract

Simultaneous monitoring of multiple fields of view (FOVs) by multiscale stereo-digital image correlation (stereo-DIC) can quantify the deformation of a material when localized phenomena occur within a larger FOV or moving object. In multiscale deformation measurement via stereo-DIC, optimization of the digital speckle patterns (DSPs) is essential to achieve high accuracy and efficiency. This work optimizes and fabricates multispectral DSPs used for multiple scales. First, an optimization of the DSP for two FOVs is achieved using both spatial modulation and specified spectra. A spatially modulated DSP is compared with two spectral DSPs achieved by visible and ultraviolet-excited blue light. Then, a spatially modulated visible DSP fabricated by an ultraviolet printer overlaid with an ultraviolet-excited blue DSP fabricated by a photosensitive seal is designed for multiscale stereo-DIC measurements of three FOVs. Experiments were performed to illustrate the functionality and utility of this multiscale DSP. Such experimental analyses can supply adequate full-field data to validate localized or kinetic mechanical behavior.