Applications in Nonbiological Materials

Rabal, H.; Braga, Roberto; Trivi, Marcelo

doi:10.1201/9781315219080-9

Cited by 16 publications

(23 citation statements)

References 1 publication

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“…The dynamics of the speckle variation were monitored using second-order statistics [ 29 ], building the time history speckle pattern (THSP) matrices and co-occurrence matrix (COM) using a selection of random points in the prime image to create the THSP [ 30 ]. From the COM, we obtained the absolute values of differences (AVD) method [ 31 ], expressed in Equation (1):

where the COM is the co-occurrence matrix related to the THSP, and the i and j variables represent the i line and the j column of each point of the COM matrix:

…”

Section: Methodsmentioning

confidence: 99%

A Portable Dynamic Laser Speckle System for Sensing Long-Term Changes Caused by Treatments in Painting Conservation

Pérez

González-Peña

Braga

et al. 2018

Sensors

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Dynamic laser speckle (DLS) is used as a reliable sensor of activity for all types of materials. Traditional applications are based on high-rate captures (usually greater than 10 frames-per-second, fps). Even for drying processes in conservation treatments, where there is a high level of activity in the first moments after the application and slower activity after some minutes or hours, the process is based on the acquisition of images at a time rate that is the same in moments of high and low activity. In this work, we present an alternative approach to track the drying process of protective layers and other painting conservation processes that take a long time to reduce their levels of activity. We illuminate, using three different wavelength lasers, a temporary protector (cyclododecane) and a varnish, and monitor them using a low fps rate during long-term drying. The results are compared to the traditional method. This work also presents a monitoring method that uses portable equipment. The results present the feasibility of using the portable device and show the improved sensitivity of the dynamic laser speckle when sensing the long-term process for drying cyclododecane and varnish in conservation.

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where the COM is the co-occurrence matrix related to the THSP, and the i and j variables represent the i line and the j column of each point of the COM matrix:

…”

Section: Methodsmentioning

confidence: 99%

A Portable Dynamic Laser Speckle System for Sensing Long-Term Changes Caused by Treatments in Painting Conservation

Pérez

González-Peña

Braga

et al. 2018

Sensors

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“…In addition, the movement of RBCs will cause random intensity fluctuations over time in the located pixel, resulting in localized intensity fluctuations in the speckle pattern, which forms the dynamic speckle. In contrast, the background tissue outside the vessel remains stationary, so the intensity of the speckle in that region does not change with time, forming a static speckle [6]. The static speckle will seriously damage image quality.…”

Section: Introductionmentioning

confidence: 99%

Laser speckle contrast imaging based on spatial frequency domain filtering

Zhai

et al. 2023

Journal of Biophotonics

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We proposed a novel method to separate static and dynamic speckles based on spatial frequency domain filtering. First, the raw speckle image sequence is processed frame by frame through 2D Fourier transform, low‐pass and high‐pass filtering in the spatial frequency domain, and inverse Fourier transform. Then, we can obtain low‐ and high‐frequency image sequences in the spatial domain. Second, we averaged both sequences in the time domain. After the above processing, we obtain the mean intensities of the dynamic and static speckle components in the spatial domain. Finally, we calculated the time‐averaged modulation depth to map the 2‐D blood flow distribution. Both phantom and vivo experiments demonstrated that the proposed method could effectively suppress the background non‐uniformity and has the advantage of high computational efficiency. It also can effectively improve image contrast, contrast‐to‐noise ratio, and imaging dynamic range.

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“…Laser speckle imaging (LSI) has been extensively used to monitor the activity of biological as well as non-biological samples [1][2][3]. To extract information from the LSI data, several processing methods are used to quantify the activity of the sample.…”

Section: Introductionmentioning

confidence: 99%

Modeling of laser speckles of heterogeneous dynamics in drying and aging paint dispersions using a view-based temporal template method

Ansari¹,

Mujeeb²

2018

Laser Phys.

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Assessments of the microscopic mechanism underlying the phenomenon of drying and aging of various paint dispersions are important for the requirements of sustainable and high-quality paints. The present work demonstrates the application of the motion history image (MHI) algorithm to visualize the microscopic mechanisms during drying and aging of different paints dispersions. We assessed the micromechanical dynamics of the drying process on laser speckle imaging data after generating the MHI maps. The processes such as cracking and delamination of paint on a glass substrate and the flow of an imbibition front on a porous substrate were analyzed using the MHI analysis, which identifies the locations where the phenomenon evolves with time.

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Applications in Nonbiological Materials

Cited by 16 publications

References 1 publication

A Portable Dynamic Laser Speckle System for Sensing Long-Term Changes Caused by Treatments in Painting Conservation

A Portable Dynamic Laser Speckle System for Sensing Long-Term Changes Caused by Treatments in Painting Conservation

Laser speckle contrast imaging based on spatial frequency domain filtering

Modeling of laser speckles of heterogeneous dynamics in drying and aging paint dispersions using a view-based temporal template method

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