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1.
Reliability of biospeckle image analysis 总被引:1,自引:0,他引:1
Roberto Alves Braga Junior Bruno Oliveira Silva Giovanni Rabelo Ricardo Marques Costa Adilson Machado Enes Nelly Cap Hctor Rabal Ricardo Arizaga Marcelo Trivi Graham Horgan 《Optics and Lasers in Engineering》2007,45(3):390
This paper presents an analysis of the time history of speckle patterns (THSP) that is one of the most used procedures to evaluate the biological activity by biospeckle images. THSPs generated by numerical simulations, obtained in a controlled drying of paint experiment and in dead and alive bean seeds under laser illumination were evaluated. We used first- and second-order statistics of the dynamic speckle patterns for different time and spatial amounts of data. We have tested both square and rectangular windows in the space time domain. The results show the agreement with a theoretical curve and comparisons between different window sizes. 相似文献
2.
We describe some aspects of the measurement of dynamic speckle activity. We propose the use of the co-occurrence matrix of the time history of the intensity of a speckle pattern. Then we suggest a measure of the activity based on the use of one of its second order moments. Some numerical simulations were performed for testing purposes. The method was applied to the study of the drying of paint and was compared with gravimetric measurements. Experimental results obtained are shown and a good correlation is obtained. 相似文献
3.
Ichirou Yamaguchi Masayuki Yokota Takasi Ida Mizuki Sunaga Koichi Kobayashi 《Optical Review》2007,14(6):362-364
The state of drying paint is monitored from the dynamic behaviors of the speckle pattern arising from laser illumination of
the region inspected. Temporal variation of the peak height of the cross-correlation function between successive frames taken
with a fixed interval is plotted until the peak maintains a stationary maximum value. We used a speckle pattern in the diffraction
field for monitoring of a single region and that in the image field for simultaneous monitoring of various regions. Both the
normal and the phase-only algorithms were compared for cross-correlation computation. The former showed more distinct variation
of peak height. 相似文献
4.
Simulation of dynamic speckle sequences and its application to the analysis of transient processes 总被引:2,自引:0,他引:2
A. Federico G.H. Kaufmann G.E. Galizzi H. Rabal M. Trivi R. Arizaga 《Optics Communications》2006,260(2):493-499
Dynamic speckle has been used in recent years to analyse several transient processes that are produced in industrial and biological applications. We present here a numerical simulation to generate a temporal sequence of dynamic speckle patterns which is based on a model used for speckle formation by the superposition of waves from discrete scattering centres. It is demonstrated that the first and second statistics of the intensity of each speckle image, the time history of the speckle pattern, the temporal evolution of the correlation coefficient, and the power spectral density of the intensity generated by the proposed model reproduce quite well those obtained from experimentally recorded data. The process of a fast drying paint is presented as an example of the application of the proposed numerical model. 相似文献
5.
利用动态激光散斑的方法研究了白蛋白的酸致变性过程。首先,利用动态散斑理论模拟生成了动态散斑序列图;然后,利用模拟和实验散斑图的时间序列散斑图及其灰度共生矩阵对白蛋白的酸致变性过程进行了分析;接着,又利用灰度共生矩阵的惯性矩和不同阶段的四幅散斑图的平均对比度图对该过程进行了更深入的研究。理论模拟和实验研究结果表明,在白蛋白酸致变性过程中,胶体溶液中的蛋白质微粒的运动由剧烈逐渐变得缓慢;同时,微粒数量减少而微粒尺寸增加。研究表明,动态激光散斑方法是一种实时、快速、有效的研究白蛋白变性过程的新手段。 相似文献
6.
This paper focuses on the application of laser speckle technique for the assessment of the effectiveness of laser cleaning of cementitious surfaces. Laser speckle-based methods are non-contact, highly resolving techniques for the measurement of displacement, rotation, and strain of an illuminated area on a rough surface. Since the intensity of reflected light depends on the geometrical microstructure and colour of the samples, any alterations of the surface result in different speckle images. Analysis of speckle images presented here is based on the analysis of the distribution of intensity of reflected light obtained in a selected plane, and analysis of statistical parameters describing such distribution (skewness and kurtosis). A wide range of laser-cleaned mortar samples with different geometrical microstructure and moisture content has been subjected to the assessment by He-Ne laser. Laser speckle method has been successfully used to identify the effectiveness of the laser cleaning process with respect to different surface conditions. It appears that the changes in kurtosis and skewness should be mainly associated with the alterations of geometrical microstructure. Whereas, mean light intensity seemed to depend predominantly on the mortar's absorption characteristics (colour). 相似文献
7.
The application of the dynamic laser speckle as a reliable instrument to achieve maps of activity in biological material is available in literature optics and laser. The application, particularly in live specimens, such as animals and human beings necessitated some approaches to avoid the kinking of the bodies, which creates changes in the patterns undermining the biological activity under monitoring. The adoption of online techniques circumvented the noise generated by the kinking, however, with considerable reduction in the resolution and definition of the activity maps. This work presents a feasible alternative to the routine online methods based on the Motion History Image (MHI) methodology. The adoption of MHI was tested in biological and non-biological samples and compared with online as well as offline procedures of biospeckle image analysis. Tests on paint drying was associated to alcohol volatilization, and tests on a maize seed and on growing of roots confirmed the hypothesis that the MHI would be able to implement an online approach without the reduction of resolution and definition on the resultant images, thereby presenting in some cases results that were comparable to the offline procedures. 相似文献
8.
根据激光散斑相关测量中采用的插值法、梯度算法和牛顿一拉夫森迭代法3种亚像素位移算法的特点,逐一在亚像素尺度计算出磁流体干燥过程中的同一激光散斑图的偏均值和标准差变化曲线。基于得到的偏差均值和标准差讨论了3种算法处理激光散斑图的特点,比较了3种算法处理散斑图的计算精度、稳定性和计算用时。结果显示,在小变形的亚像素位移测量时,梯度算法的精度较高,且较为稳定,计算效率也较牛顿一拉夫森算法快约9倍。因此,在进行小变形亚像素位移测量时,采用梯度算法计算激光散斑是有效的。 相似文献
9.
Velocity and density field measurements based on image processing of laser speckle or pseudo-speckle pattern have been developed. Laser speckle velocimetry (LSV) or white-light speckle velocimetry (WSV), which corresponds to a high-image-density PIV, gives a local velocity vector map or whole field velocity contour map of a two-dimensional flow field seeded densely with fine particles. This technique has an advantage in high-speed flow measurement without limit of frame rate except for directional ambiguity. New techniques of laser speckle photography and laser speckle interferometry by means of digital image processing have been developed recently for density field measurements. In laser speckle photography, a local density gradient vector map is reconstructed by cross-correlation evaluation between the reference and the object speckle patterns. In laser speckle interferometry, an equi-density contour map is reconstructed by image subtraction between the reference and the object interferometric speckle patterns. 相似文献
10.
K. D. Kihm 《Optics and Lasers in Engineering》1998,29(2-3)
Laser speckle photography measures projected beam deflection of a phase object. The beam deflection measured at the solid surface will directly determine the wall-temperature gradient. Thus, the laser-speckle photography allows the evaluation of the convection-heat-transfer coefficients without the need to correct for conduction and radiation heat losses, which otherwise would be necessary. Selected results and brief discussions are presented for several natural convection-heat-transfer problems. Second, high-temperature applications of laser speckle photography shows potential as a nonintrusive means of measuring flame temperature. A fairly good agreement is shown in comparison of the laser speckle data with intrusive thermocouple data. Suggestive discussions are made to further improve the accuracy and sensitivity of the laser speckle photography technique in high-temperature applications. Finally, tomographic reconstruction of laser speckle photography data is discussed using both actual test fields and computer-synthesized phantom fields. The conventional algebraic reconstruction technique (ART) has been modified to apply for the laser speckle tomography. The efficacy of ART is examined particularly under a limited number of projections. 相似文献
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12.
Chih-Ming Liao Ping S. Huang Yi-Yuh Hwang Ming Chen Chung-Cheng Chiu 《Optics and Lasers in Engineering》2009,47(7-8):875-883
Laser speckles have been used in measurement techniques, since they were discovered to be correlated with the displacement of the light source. This paper presents a robust technique of analyzing and locating laser speckle patterns (LSPs) for a prototype of a laser optical mouse. After the speckle images are captured from the image-grabbing device, they are analyzed by the proposed image processing procedures and normalized cross-correlation (NCC) is adopted to develop position-locating rules for laser speckle patterns. To verify robustness of the proposed approach, nine different materials of mouse pad are used. Experimental results show that they have all achieved similar and promising performance. Therefore, the proposed technique can not only precisely calculate the moving directions and displacement information for laser speckles, the linearity for the prototype of laser mouse can also be verified. 相似文献
13.
Bio-speckle assessment of bruising in fruits 总被引:3,自引:0,他引:3
M. Pajuelo G. Baldwin H. Rabal N. Cap R. Arizaga M. Trivi 《Optics and Lasers in Engineering》2003,40(1-2):13-24
The dynamic speckle patterns or bio-speckle is a phenomenon produced by laser illumination of active materials, such as a biological tissue. Fruits, even hard peel ones, show a speckle activity that can be related to maturity, turgor, damage, aging, and mechanical properties. In this case, we suggest a bio-speckle technique as a potential methodology for the study of impact on apples and the analysis of bruises produced by them. The aim is to correlate physical properties of apples with quality factors using a non-contact and non-invasive technique. 相似文献
14.
R.A. Braga C.M.B. Nobre A.G. Costa T. Sáfadi F.M. da Costa 《Optics Communications》2011,284(2):646-650
When a material is illuminated with a laser beam, it is possible to verify a phenomenon known as dynamic speckle or biospeckle. It exhibits an interference image that contains lots of information about the process being analyzed, and one of its most important applications is determining the activity quantity from the materials under study. The numerical analysis of the dynamic speckle images can be carried out by means of a co-occurrence matrix (COM) that assembles the intensity distributions of a speckle pattern with regard to time. An operational method that is widely used on the biospeckle COMs is the inertia moment (IM). Some studies demonstrate that IM is more sensitive on analyzing processes that involve high activities or high frequencies if considering the spectral analysis of the phenomena. However, when this variation is not so intense, this method is less efficient. For low variations on the activity or low frequencies, qualitative methods such as wavelet based entropy and cross-spectrum analysis have presented better results; however, processes that are in the intermediate range of activity are not well covered for any of these techniques mentioned earlier. The contribution of this research is to present an alternative approach, based on the absolute value of the differences (AVD) when handling the biospeckle COM. By using AVD on the seed-drying process, was found that it is efficient on verifying the behavior of the intermediate frequencies. Accumulated sum test (Coates and Diggle) showed that AVD and IM are generated from the same stochastic process. Thus, AVD is useful as an alternative method in some cases or even as a complementary tool for analyzing the dynamic speckle, mainly when the information of the activity is not present on high frequencies. 相似文献
15.
The empirical mode decomposition (EMD) method is used to process sequences of dynamic speckle patterns to segment the differential activity that presents a sample as a function of the spatial coordinates and time. The application of the method is illustrated by segmenting bruised regions in fruits. A discussion of the obtained results and a comparison with the use of the filter bank technique are also presented. 相似文献
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17.
Laser speckle method is a well known technique that is useful for both visualization and quantitative measurement. This technique was applied to the density measurement of Mach reflection of shock waves in the present experiment. The Object of the measurement is the density field of simple Mach reflection in relatively low shock Mach number. The non-uniform flow field is divided into three regions by incident, Mach and reflected shock waves. A shock tube was employed in the present experiment. Wedges of 20 degrees and 45 degrees were placed in the test section. YAG laser was employed as a light source. Speckle photograph was taken by a digital still camera. Simple subtraction between the reference and flow images shows a shock pattern and a degree of the correlation of speckle pattern in the flow field. Thus, we can obtain a visualized flow image showing a configuration of Mach reflection from speckle photograph. Speckle photographs which was obtained in the experiments were processed with cross-correlation method. A reconstructed density gradient vector map of Mach reflection was obtained. Comparing the experimental result with numerical one, the measured density gradient shows a good agreement with theoretical prediction. 相似文献
18.
Han Bingyuan Xu Yawei Zhou Kebing Lei Weining Li Xiaoping Zhang Yan Huang Qingwei Zhu Sheng Zhang Hengyi 《Journal of Russian Laser Research》2021,42(5):598-608
Journal of Russian Laser Research - To study the process of removing acrylic polyurethane paint from a 2024 aluminum alloy surface with a pulsed laser, we establish a finite-element model via... 相似文献
19.
This communication reports the observation of a typical set of fringes in transmission, when a wet processed photographic plate, exposed to laser speckles and kept tilted with respect to normal, isscanned by a thin laser beam. A possible explanation for the fringe formation is given which is based on the speckle stretching due to swelling of the emulsion. A method has been proposed to estimate emulsion swelling due to wet processing and the rate of its shrinkage during subsequent drying process. Experimental results are presented for Kodak 649-F spectroscopic plates. 相似文献
20.
Gyanendra SheoranShobhna Sharma Chandra Shakher 《Optics and Lasers in Engineering》2011,49(1):159-166
We have proposed and demonstrated a new application of lensless Fourier transform digital holographic interferometry to study/monitor the drying process and detection of cracking/disbonding of the painted surface by observing the dynamics of interference phase maps. The technique can monitor the rate of drying of paint and visualize the state of dryness and crack/disbond. The technique is simple and easy to implement. 相似文献