Multiscale deformation measurements leveraging tailorable and multispectral speckle patterns

Patent metadata

Field	Value
Publication number	US-10845187-B2
Application number	US-201916289842-A
Country	US
Kind code	B2
Filing date	Mar 1, 2019
Priority date	Mar 2, 2018
Publication date	Nov 24, 2020
Grant date	Nov 24, 2020

Abstract

Remote measurements using images are particularly useful in structural health monitoring cases in which the installation of contact sensors is difficult. Some limitations, though, associated with photogrammetry-type optical metrology involve the application of speckle patterns, which become even more important with variable working distance or when the required resolution and sensitivity are not a priori known. In this context, multispectral sensing combined with tailored speckle patterns can circumvent some of the challenges of acquiring data at different working distances. The present invention uses multispectral imaging combined controlled generation of speckle patterns to demonstrate an approach for remote sensing related to deformation measurements at the structural level. To demonstrate this approach, two speckle patterns were designed for measurements at specified working distances. The results show that the spectral specific reflectivity of the speckle patterns allow for spatial overlay without affecting imaging within either spectral range considered, which results in the extraction of multiscale deformation measurements.

First claim

What is claimed is:

1. A multiscale deformation monitoring method comprising the steps of:
(a) selecting a structure by choosing a field of view (FOV), the FOV having a defined size;
(b) applying a first optimized speckle pattern to the structure such that the first speckle pattern is only visible within a first wavelength range, wherein the first speckle pattern has first properties comprising a first speckle size, a first inter-speckle spacing, and a first spatial distribution, wherein the first properties are controllable in relation to the FOV, and wherein the first properties can be reproduced for any other desired FOV while preserving the first properties;
(c) applying a second optimized speckle to the structure, different from the first speckle pattern, such that the second speckle pattern is only visible within a second wavelength range, different from the first wavelength range, wherein the second speckle pattern has second properties comprising a second speckle size, a second inter-speckle spacing, and a second spatial distribution, wherein the second properties are controllable in relation to the FOV, and wherein the second properties can be reproduced for any other desired FOV while preserving the second properties; and
(d) using the first and second speckle patterns to apply a digital image correlation method (DIC) to the structure and to extract three-dimensional deformation and damage information from the structure, wherein the first speckle pattern is controlled and customized to provide information at an arbitrary first scale, the first scale being smaller than the size of the FOV, and wherein the second speckle pattern is controlled and customized to provide information at a second scale, the second scale being the size of the FOV.

2. The method according to claim 1 , wherein the first wavelength range is within the visible light range.

3. The method according to claim 2 , wherein the second wavelength range is within the ultraviolet wavelength range.

4. The method according to claim 2 , wherein the second wavelength range is outside the visible light range.

5. The method according to claim 1 , wherein the first speckle pattern is comprised of speckles having a first size and wherein the second speckle pattern is comprised of speckles having a second size, different from the first size.

6. The method according to claim 1 , wherein step (d) comprises spacing DIC cameras a predetermined distance from the structure.

7. The method according to claim 6 , wherein step (d) comprises placing the DIC cameras a first distance from the structure to image the first speckle pattern and placing the DIC cameras a second distance from the structure to image the second speckle pattern.

8. A multiscale deformation monitoring method comprising the steps of:
(a) applying a first optimized speckle pattern to a structure such that speckles in the first speckle pattern have a first speckle size, a first inter-speckle spacing, and a first spatial distribution;
(b) applying a second optimized speckle pattern to the structure such that speckles in the second speckle pattern have a second speckle size, a second inter-speckle spacing, and a second spatial distribution than the first pattern, different from the first size range, the first inter-speckle distance, and the first spatial distribution;
(c) applying a load to the structure;
(d) using the cameras to record images of the first and second speckle patterns using a DIC method; and
(e) extracting three-dimensional deformation and damage information from the structure wherein the first speckle pattern is leveraged to provide information at an arbitrary first scale, the first scale being smaller than the size of the FOV, and wherein the second speckle pattern is leveraged to provide simultaneously information at a second scale, the second scale being the size of the FOV.

9. The method according to claim 8 , wherein the first wavelength range is within the visible light range.

10. The method according to claim 9 , wherein the second wavelength range is within the ultraviolet wavelength range.

11. The method according to claim 9 , wherein the second wavelength range is outside the visible light range.

12. The method according to claim 8 , wherein the first speckle pattern is comprised of speckles having a first size and wherein the second speckle pattern is comprised of speckles having a second size, different from the first size.

13. The method according to claim 8 , wherein step (d) comprises spacing the DIC cameras a predetermined distance from the structure.

14. The method according to claim 13 , wherein step (d) comprises placing the DIC cameras a first distance from the structure to image the first speckle pattern and placing the DIC cameras a second distance from the structure to image the second speckle pattern.

Assignees

• Univ Drexel

Inventors

• Kontsos Antonios
• Melvin Domin Mathew Fnu
• Ellenberg Andrew James
• Bartoli Ivan

Classifications

• G01B11/16 Primary

  for measuring the deformation in a solid, e.g. optical strain gauge · CPC title

• G01B11/167

  by projecting a pattern on the object · CPC title

• G01N21/4788

  Diffraction (for sizing particles G01N15/0205) · CPC title

• G01N2021/95615

  with stored comparision signal · CPC title

• G06T7/521

  from laser ranging, e.g. using interferometry; from the projection of structured light · CPC title