Related Experiment Video
Updated: Jun 14, 2026
06:56
Micro/Nano-scale Strain Distribution Measurement from Sampling Moiré Fringes
Published on: May 23, 2017
In-plane displacement and strain measurement by speckle interferometry and moire derivation
Applied Optics
|March 25, 2010
Summary
Speckle interferometry uses wave front correlation to analyze fringe visibility. This study examines how object displacement, deformation, strain, and defocusing impact fringe visibility in in-plane displacement measurements.
Area of Science:
- Optical Metrology
- Speckle Interferometry
- Wave Optics
Background:
- Speckle interferometry is a powerful technique for measuring surface displacements.
- Fringe visibility is a critical parameter determining measurement accuracy.
- Understanding factors affecting fringe visibility is essential for reliable measurements.
Purpose of the Study:
- To apply the coefficient of correlation of interfering wave fronts to speckle interferometry.
- To analyze parameters influencing fringe visibility in in-plane displacement measurements.
- To investigate the effects of arbitrary displacement, deformation, strain, and defocusing on fringe visibility.
Main Methods:
- Theoretical application of the coefficient of correlation for wave fronts.
- Analysis of fringe formation and visibility under various object surface conditions.
- Experimental validation of theoretical predictions.
Main Results:
- Identified key parameters affecting in-plane displacement fringe visibility.
- Quantified the influence of object surface strain and defocusing on fringe visibility.
- Demonstrated the correlation between wave front properties and fringe visibility.
Conclusions:
- The coefficient of correlation provides a framework for understanding fringe visibility in speckle interferometry.
- Object displacement, deformation, strain, and defocusing significantly impact measurement quality.
- Results offer insights for optimizing speckle interferometry techniques for accurate displacement analysis.
Related Concept Videos
01:27Measurements of Strain
Strain quantifies the deformation of a material under force, typically measured as normal strain, which represents the change in length when compared with the original length. Electrical strain gauges are used for enhanced accuracy. These devices consist of a conductive wire mounted on a paper backing that adheres to the material's surface. These gauges operate on the piezoresistive effect, where the wire's electrical resistance changes in response to mechanical deformation. The strain gauge...
01:29Three-Dimensional Analysis of Strain
Three-dimensional strain analysis is crucial for understanding how materials deform under stress, particularly in elastic, homogeneous materials. This method employs principal stress axes to simplify complex stress states into more understandable forms. Subjected to stress, a small cubic element within a material either expands or contracts along these axes, transforming into a rectangular parallelepiped. This transformation effectively illustrates the material's deformation. The principal...
01:12Transformation of Plane Strain
When analyzing elongated structures like bars subjected to uniformly distributed loads, it is essential to understand the transformation of plane strain when coordinate axes are rotated. This transformation helps to assess how material deformation characteristics vary with orientation, which is crucial in materials science and structural engineering.
Under plane strain conditions, typical for members where one dimension significantly exceeds the others, deformations and resultant strains are...
Under plane strain conditions, typical for members where one dimension significantly exceeds the others, deformations and resultant strains are...
01:18Mohr's Circle for Plane Strain
Mohr's circle is a crucial graphical method used to analyze plane strain by plotting strain on a set of cartesian coordinates, where the abscissa is normal strain ∈ and the ordinate is shear strain γ. Similarly to Mohr’s circle for plane stress, two points X and Y are plotted. Their coordinates are (∈x, -γXY) and (∈Y, γXY), respectively.
Mohr's circle visually represents the strain states under various conditions, which is essential for understanding material behavior. The center of Mohr's...
Mohr's circle visually represents the strain states under various conditions, which is essential for understanding material behavior. The center of Mohr's...
01:18Transformation of Plane Stress
Studying stress transformation is essential in understanding how stress components within a material, like a cube under plane stress, change with rotation. This change is analyzed by considering a prismatic element within the cube. As the element rotates, the stress components acting on it—both normal and shearing stresses—change in magnitude and orientation. This change is quantified using trigonometric functions of the rotation angle, relating the forces acting on the rotated element's faces...