Evaluation of activity through dynamic laser speckle using the absolute value of the differences

Braga, Roberto A.; Nobre, C.M.B.; Costa, Anderson Gomide; Sáfadi, Thelma; Costa, F.M.

doi:10.1016/j.optcom.2010.09.064

Cited by 56 publications

(18 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…One of the calculations used to measure the activity of the biological media from THSP images is the AVD. 17 The AVD processing is based on the generation of a single numeric value from THSP. For the numerical analysis, active zones of the sample taken as the region of interest were analyzed with respect to their behavior in time by means of the AVD method.…”

Section: Numerical Evolution Of Absolute Value Of Differencesmentioning

confidence: 99%

Real time and online dynamic speckle assessment of growing bacteria using the method of motion history image

et al. 2016

View full text Add to dashboard Cite

This paper reports the application of the motion history image (MHI) method for biospeckle processing of a bacterial growth. The method avoids the complexity as well as the large computation in sequence-matching-based methods and detects whether the speckle structure has changed or not. Encouraging experimental results on the real-time evolution of the growing bacteria during 12 h demonstrate the effectiveness of the proposed method. The MHI presented an online result without loss of resolution and definition. In turn, the MHI also presented the ability to provide a close answer to the traditional offline method of generalized differences.

show abstract

Section: Numerical Evolution Of Absolute Value Of Differencesmentioning

confidence: 99%

Real time and online dynamic speckle assessment of growing bacteria using the method of motion history image

et al. 2016

View full text Add to dashboard Cite

show abstract

“…It exhibits an interference image that contains lots of information about the characteristics of the illuminated scattering object and the process being analyzed. Being optical non-contact pattern the important aspects of speckles are determining the activity quantity from the materials under study (Braga et al, 2011). The time varying speckle pattern also plays an important role in many physical phenomena like in measurement of dynamic object (Semenov et al, 2010), metrological and stress corrosion analysis (Chiang & Kin, 1982;Lu & Zou, 2010), surface deformation and roughness measurement (Ling et al, 1986), bio-speckle study in seed analysis (Nobre et al, 2009) besides smoothing of the laser beam (Veron et al, 1988).…”

Section: Experiments Laser Beam Smoothing Study Using 2 Mw He-ne Lasermentioning

confidence: 99%

Laser produced thin metallic planar mini-flyer generation using fiber optic plate

et al. 2013

View full text Add to dashboard Cite

Laser produced planar mini flyer generation has widely gained importance owing to its wide ranging applications in the field of condensed matter, astrophysics, material research, shock phenomenon, etc. Flattop smooth laser beam profile as driver is the primary requirement for planar flyer generation besides special multilayered target geometry. We present here laser produced thin metallic planar mini-flyer generation using a fiber optic plate (FOP) of 8 mm thickness and about 6 μm fiber dimension. This technique is unique in the sense that it doesn't require large length as compared to optical fiber. A Gaussian shape laser beam from a laser oscillator was allowed to fall on the FOP generating a speckle pattern. This pattern was relayed and amplified using lenses and laser amplifiers to achieve energy of about 400 mJ. The beam was focused on a substrate (fused silica) based multilayered target on which flyer disks of different materials such as Al. Cu, Br, and Ta were attached. Velocities as high as 400 m/s was measured for Al flyer of 1.5 mm diameter and thickness 50 μm. Flyer disks were completely recovered after the laser shot. We also present a theoretical analysis along with experimental results of the laser beam smoothing technique using a He-Ne laser and FOP. Each channel of the FOP acts as a small single mode optical fiber. The basic idea was to divide the incoming coherent beam into many beam-lets introducing random distribution in length or/and diameter of optical fibers of FOP. The individual FOP channel acts as a diverging source because of single mode fiber with natural divergence λ/d. However, due to the small randomness in length or diameter, the individual diffraction sources are not in phase. This results in the generation of speckles in both near (Fresnel) and far field (Fraunhoffer) destroys the spatial coherence of the beam.

show abstract

“…The replacement of the absolute value by the squared value has been studied in previous works [19,20], but such works have studied different measures.…”

Section: B Alternative Generalized Difference Gdmentioning

confidence: 99%

Alternative measures for biospeckle image analysis

et al. 2012

View full text Add to dashboard Cite

Biospeckle is a technique whose purpose is to observe and study the underlying activity of some material. It has its roots in optical physics, and its first step is an image acquisition process that produces a video sequence of the reflection of a laser. The video content can be analyzed to have an interpretation of the activity of the observed material. The literature on this subject presents several different measures for analyzing the video sequence. Three of the most popular measures are the generalized difference (GD), the weighted generalized difference (WGD), and Fujii's method. These measures have drawbacks such as high computation time or limited visual quality of the results. In this paper, we propose (i) an alternative O(n) algorithm for the computation of the GD, (ii) an alternative measure based on the GD, (iii) an alternative measure based on the WGD, and (iv) a generalized definition of the Fujii's method with better visual quality. We discuss the similarities between the new measures and the existent ones, showing when they are applicable. We prove the gain in time computation. The proposed measures will help researchers to gain time during their research and to be able to develop faster tools based on biospeckle application.

show abstract

Evaluation of activity through dynamic laser speckle using the absolute value of the differences

Cited by 56 publications

References 20 publications

Real time and online dynamic speckle assessment of growing bacteria using the method of motion history image

Real time and online dynamic speckle assessment of growing bacteria using the method of motion history image

Laser produced thin metallic planar mini-flyer generation using fiber optic plate

Alternative measures for biospeckle image analysis

Contact Info

Product

Resources

About