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
Keyword(s):  
Intensity Fluctuation ◽  
Laser Speckle ◽  
Zero Crossing ◽  
Integrated Intensity

Laser speckle imaging based on intensity fluctuation modulation

2013 ◽  
Vol 38 (8) ◽  
pp. 1313 ◽  
Author(s):  
Yaguang Zeng ◽  
Mingyi Wang ◽  
Guangping Feng ◽  
Xianjun Liang ◽  
Guojian Yang
Keyword(s):  
Intensity Fluctuation ◽  
Laser Speckle ◽  
Laser Speckle Imaging ◽  
Speckle Imaging

Measurement of the Transient Velocity of Nanoparticles in Flowing Nanofluids by Using the Method of Dynamic Laser Speckles

2012 ◽  
Vol 226-228 ◽  
pp. 1852-1857
Author(s):  
Qin Yan ◽  
Jian Lu ◽  
Xiao Wu Ni
Keyword(s):  
Laser Beam ◽  
Intensity Fluctuation ◽  
Incident Light ◽  
Horizontal Axis ◽  
Experimental Results ◽  
Zero Crossing ◽  
Moving Direction ◽  
Transient Velocity ◽  
Zero Crossing Rate ◽  
Laser Speckles

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.

scholarly journals In vivolabel-free microangiography by laser speckle imaging with intensity fluctuation modulation

2013 ◽  
Vol 18 (12) ◽  
pp. 126001 ◽  
Author(s):  
Mingyi Wang ◽  
Yaguang Zeng ◽  
Xianjun Liang ◽  
Guanping Feng ◽  
Xuanlong Lu ◽  
...  
Keyword(s):  
Intensity Fluctuation ◽  
Laser Speckle ◽  
Laser Speckle Imaging ◽  
Speckle Imaging

Point-wise and whole-field laser speckle intensity fluctuation measurements applied to botanical specimens

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

Automatic measurement of SAED patterns from asbestos minerals

1988 ◽  
Vol 46 ◽  
pp. 846-847
Author(s):  
J. C. Russ ◽  
T. Taguchi ◽  
P. M. Peters ◽  
E. Chatfield ◽  
J. C. Russ ◽  
...  
Keyword(s):  
Diffraction Pattern ◽  
High Precision ◽  
Diffraction Data ◽  
Automatic Measurement ◽  
Automatic Method ◽  
Important Method ◽  
X Ray ◽  
Integrated Intensity ◽  
Asbestiform Minerals ◽  
True Center

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.

Structure Information From Electron Diffraction Intensities

1990 ◽  
Vol 48 (2) ◽  
pp. 516-517
Author(s):  
J. Gjønnes ◽  
N. Bøe ◽  
K. Gjønnes
Keyword(s):  
Computational Effort ◽  
Unit Cell ◽  
Small Unit ◽  
Structure Information ◽  
Dispersion Surface ◽  
Integrated Intensity ◽  
The One ◽  
Image Position ◽  
Convergent Beam ◽  
Beam Patterns

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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