Laser Speckle Velocimeter Using A Zero-Crossing Technique For Spatially Integrated Intensity Fluctuation

1981 ◽  
Vol 20 (2) ◽  
Author(s):  
Nobukatsu Takai ◽  
Toshiaki Iwai ◽  
Toshimitsu Asakura
2013 ◽  
Vol 38 (8) ◽  
pp. 1313 ◽  
Author(s):  
Yaguang Zeng ◽  
Mingyi Wang ◽  
Guangping Feng ◽  
Xianjun Liang ◽  
Guojian Yang

2012 ◽  
Vol 226-228 ◽  
pp. 1852-1857
Author(s):  
Qin Yan ◽  
Jian Lu ◽  
Xiao Wu Ni

Experimental equipments are designed for the zero-crossing method of dynamic laser speckles to investigate the moving nature of nanoparticles in flowing nanofluids. After the experiments the velocity of nanoparticles in flowing nanofluids is determined according to its relationship with the zero-crossing rate of speckle intensity fluctuation. The results show that the zero-crossing rate is very sensitive to the velocity of nanoparticles when the velocity of nanofluids ranges from 17.6 mm/s to 60.2 mm/s. A TEM10 mode–like laser beam is designed and taken as an incident light to detect the moving direction of nanoparticles in flowing nanofluids. The moving direction of nanoparticles is parallel to the horizontal axis of the TEM10 mode-like laser beam when the zero-crossing rate reaches maximum. Experimental results show that the moving direction of nanoparticles can also be detected by using the zero-crossing method.


2013 ◽  
Vol 18 (12) ◽  
pp. 126001 ◽  
Author(s):  
Mingyi Wang ◽  
Yaguang Zeng ◽  
Xianjun Liang ◽  
Guanping Feng ◽  
Xuanlong Lu ◽  
...  

1997 ◽  
Vol 28 (6) ◽  
pp. 443-456 ◽  
Author(s):  
Yang Zhao ◽  
Junlan Wang ◽  
Xiaoping Wu ◽  
Fred W. Williams ◽  
Richard J. Schmidt

Author(s):  
J. C. Russ ◽  
T. Taguchi ◽  
P. M. Peters ◽  
E. Chatfield ◽  
J. C. Russ ◽  
...  

Conventional SAD patterns as obtained in the TEM present difficulties for identification of materials such as asbestiform minerals, although diffraction data is considered to be an important method for making this purpose. The preferred orientation of the fibers and the spotty patterns that are obtained do not readily lend themselves to measurement of the integrated intensity values for each d-spacing, and even the d-spacings may be hard to determine precisely because the true center location for the broken rings requires estimation. We have implemented an automatic method for diffraction pattern measurement to overcome these problems. It automatically locates the center of patterns with high precision, measures the radius of each ring of spots in the pattern, and integrates the density of spots in that ring. The resulting spectrum of intensity vs. radius is then used just as a conventional X-ray diffractometer scan would be, to locate peaks and produce a list of d,I values suitable for search/match comparison to known or expected phases.


Author(s):  
J. Gjønnes ◽  
N. Bøe ◽  
K. Gjønnes

Structure information of high precision can be extracted from intentsity details in convergent beam patterns like the one reproduced in Fig 1. From low order reflections for small unit cell crystals,bonding charges, ionicities and atomic parameters can be derived, (Zuo, Spence and O’Keefe, 1988; Zuo, Spence and Høier 1989; Gjønnes, Matsuhata and Taftø, 1989) , but extension to larger unit cell ma seem difficult. The disks must then be reduced in order to avoid overlap calculations will become more complex and intensity features often less distinct Several avenues may be then explored: increased computational effort in order to handle the necessary many-parameter dynamical calculations; use of zone axis intensities at symmetry positions within the CBED disks, as in Figure 2 measurement of integrated intensity across K-line segments. In the last case measurable quantities which are well defined also from a theoretical viewpoint can be related to a two-beam like expression for the intensity profile:With as an effective Fourier potential equated to a gap at the dispersion surface, this intensity can be integrated across the line, with kinematical and dynamical limits proportional to and at low and high thickness respctively (Blackman, 1939).


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