A computational hybrid proposal for imaging the stress field through a three-wavelength phase stepping

Restrepo-Martínez, Alejandro; Toro, Hermes A. Fandiño; León, Juán

doi:10.1364/cosi.2021.cth4e.3

Cited by 1 publication

(2 citation statements)

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“…With the last set of images and equations, a hybrid wavelength step technique (HWST) method was developed [16][17] . It needs only the bright field image because the dark field images are generated computationally based on the one proposed by Briñez in reference 18 .…”

Section: Light Intensitymentioning

confidence: 99%

“…All these facts limit a wide use of this phase-shifting method. This paper has as contribution the development of an algorithm that uses the structure of a standard load-stepping method [14][15][16][17] but incorporates digital processing for generating a special color image that allows to produce phase shifting, avoiding the problems associated with the limitations of the load, the number of images, movement, or deformation of the sample. Thus, this article proposes a new three-wavelength chromatic-corrected image hybrid phase shift method that works for single-camera digital photoelasticity applications.…”

Section: Introductionmentioning

confidence: 99%

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A new three-wavelength chromatic-corrected hybrid phase shifting method for single-camera digital photoelasticity

Restrepo-Martínez

2023

Modeling Aspects in Optical Metrology IX

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Digital photoelasticity is a non-contact inspection technique, that requires new strategies to unwrap the stresses map based on color images. Therefore, this paper presents a new three-wavelength chromatic-corrected hybrid phase-shift method for single-camera digital photoelasticity applications. For the experiments, the intensities of isochromatic images are simulated considering a birefringent sample compressed and a circular polariscope configured to produce a bright field image that avoids the effects caused by isoclinics. To increase the range of the fringe order, three LEDs with peaks of close wavelengths were used. Additionality, for each LED a RGB color image is simulated. The red channel of each image is used to generate a new synthetic chromatic-corrected image (CCI) thereby: the red channel of λ3 is the red channel of the new CCI, and the green and blue channels of the CCI use the respective red channels of λ2 and λ1; additionally, the wavelengths must satisfy the following condition (λ3 > λ2 >λ1). An inverted image of the CCI is computed. Thus, with the CCI and its inverted image, six images are stored, and with these images and some trigonometric relations proposed by Ekman and Nurse a wrapped phase map is extracted. Finally, an unwrapping algorithm is applied to reconstruct the stresses map. The results show that the method improves the detected maximum order and reduces stress map distortions compared to similar color phase shifting approaches. Furthermore, since the algorithm requires only a camera and a circular polariscope setup, it can be implemented in dynamic experimental applications.

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Section: Light Intensitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A new three-wavelength chromatic-corrected hybrid phase shifting method for single-camera digital photoelasticity

Restrepo-Martínez

2023

Modeling Aspects in Optical Metrology IX

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A computational hybrid proposal for imaging the stress field through a three-wavelength phase stepping

Abstract: Dynamical photoelasticity studies are affected by requiring multiple acquisitions under optical elements motion. In consequence, this paper introduces a computational hybrid technique of three-wavelength phase stepping using only one-color image to recover the stress field.

Cited by 1 publication

References 4 publications

A new three-wavelength chromatic-corrected hybrid phase shifting method for single-camera digital photoelasticity

A new three-wavelength chromatic-corrected hybrid phase shifting method for single-camera digital photoelasticity

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