Speckle correlation technique to improve the dynamic range of an optical lever

2019 ◽  
Author(s):  
S. Bhattacharya ◽  
A. Vijayakumar ◽  
J. L. Sruthy ◽  
Joseph Rosen
Keyword(s):  
Dynamic Range ◽  
Correlation Technique ◽  
Speckle Correlation ◽  
Optical Lever

scholarly journals Spatial Multiplexing Technique for Improving Dynamic Range of Speckle Correlation based Optical Lever

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Vijayakumar Anand ◽  
Shanti Bhattacharya ◽  
Joseph Rosen
Keyword(s):  
Dynamic Range ◽  
Speckle Pattern ◽  
Image Sensor ◽  
Initial Position ◽  
Spatial Multiplexing ◽  
Angular Orientation ◽  
Correlation Peak ◽  
Intensity Pattern ◽  
Speckle Correlation ◽  
Optical Lever

Abstract Speckle correlation based optical levers (SC-OptLev) possess attractive characteristics suitable for sensing small changes in the angular orientations of surfaces. In this study, we propose and demonstrate a spatial multiplexing technique for improving the dynamic range of SC-OptLev. When the surface is in its initial position, a synthetic speckle intensity pattern, larger than the area of the image sensor is created by transversely shifting the image sensor and recording different sections of a larger speckle pattern. Then, the acquired images are stitched together by a computer program into one relatively large synthetic speckle pattern. Following the calibration stage, the synthetic speckle intensity pattern is used to sense changes in the surface’s angular orientation. The surface is monitored in real-time by recording part of the speckle pattern which lies within the sensor area. Next, the recorded speckle pattern is cross-correlated with the synthetic speckle pattern in the computer. The resulting shift of the correlation peak indicates the angular orientations of the reflective surface under test. This spatial-multiplexing technique enables sensing changes in the angular orientation of the surface beyond the limit imposed by the physical size of the image sensor.

scholarly journals Implementation of a speckle-correlation-based optical lever with extended dynamic range

2019 ◽  
Vol 58 (22) ◽  
pp. 5982 ◽  
Author(s):  
A. Vijayakumar ◽  
D. Jayavel ◽  
M. Muthaiah ◽  
Shanti Bhattacharya ◽  
Joseph Rosen
Keyword(s):  
Dynamic Range ◽  
Speckle Correlation ◽  
Optical Lever ◽  
Extended Dynamic

AN OCEAN BOTTOM, D COMPONENT MAGNETOMETER

Geophysics ◽  
1967 ◽  
Vol 32 (6) ◽  
pp. 978-987 ◽  
Author(s):  
J. H. Filloux
Keyword(s):  
Electric Field ◽  
Dynamic Range ◽  
North Pacific Ocean ◽  
Mooring Line ◽  
Ocean Bottom ◽  
Magnetic Fluctuations ◽  
Sea Floor ◽  
The North ◽  
Low Profile ◽  
Optical Lever

The distribution of electric conductivity in the crustal and upper mantle materials beneath the ocean may be estimated from measurements of the relationship between the magnetic fluctuations and the induced electric field at the ocean bottom. Techniques for the measurement of the electric field have been available for a few years. The horizontal magnetic fluctuations to the magnetic east, usually called D, can be recorded with a simple instrument placed on the sea floor at any depth. This instrument uses a magnet pair which orients itself among the main horizontal field H. The coupling of the magnets to the mirror of a sensitive optical lever is delayed until the instrument has reached the bottom. There is no need to perform any orientation in situ. The instrument resolves 1 γ or less and has a dynamic range of at least 2500 γ. It is capable of recording for approximately 40 days at the rate of 30 readings per hour on self‐contained dry cells. It is lowered to the sea floor and recovered by means of a mooring line connected to a surface float. The low‐profile supporting tripod is effectively decoupled from the mooring tackle as evidenced by the lack of motion of the magnetometer during 26 days of recording. A sample of the observed fluctuations on the floor of the North Pacific Ocean, 600 km offshore, is given.

Laser speckle correlation technique application for study of aluminum nanopowder combustion

2020 ◽  
Vol 59 (5) ◽  
pp. 1263
Author(s):  
L. Li ◽  
A. V. Mostovshchikov ◽  
A. P. Ilyin ◽  
I. D. Sytnik ◽  
F. A. Gubarev
Keyword(s):  
Laser Speckle ◽  
Correlation Technique ◽  
Speckle Correlation ◽  
Aluminum Nanopowder

Full-field speckle correlation technique as applied to blood flow monitoring

2011 ◽  
Author(s):  
M. A. Vilensky ◽  
D. N. Agafonov ◽  
P. A. Timoshina ◽  
O. V. Shipovskaya ◽  
D. A. Zimnyakov ◽  
...  
Keyword(s):  
Blood Flow ◽  
Correlation Technique ◽  
Full Field ◽  
Flow Monitoring ◽  
Speckle Correlation

scholarly journals Numerical model for evaluating the speckle activity and characteristics of bone tissue under the biospeckle laser system

2021 ◽  
pp. 2150020
Author(s):  
Xin Tang ◽  
Ping Zhong ◽  
Yinrui Gao ◽  
Haowei Hu
Keyword(s):  
Bone Tissue ◽  
Temporal Evolution ◽  
Ex Vivo ◽  
Laser System ◽  
Laser Speckle ◽  
Correlation Technique ◽  
Volume Scattering ◽  
Current Time ◽  
Speckle Correlation ◽  
Spatio Temporal

This paper discusses and studies the composition and characteristics of biospeckle on the surface of bone tissues. We used a laser speckle device to capture biospeckle patterns from fresh pig bone tissue. Traditional speckle activity metrics were used to measure the speckle activity of ex vivo bone tissue over time. Both Gaussian and Lorentzian correlation functions were used to characterize the ordered and disordered motion of the bone surface, together with volume scattering, to construct the model. Using the established mathematical model of the spatio-temporal evolution of the biospeckle pattern, it is possible to account for the presence of volume scattering from the biospeckle of bones, quantify the ordered or disordered motions in the biological speckle activity at the current time, and assess the ability of laser speckle correlation technique to determine biological activity.

Optical Strain Measurement on Small Specimens Based on Laser Speckles

2008 ◽  
Vol 584-586 ◽  
pp. 237-242 ◽  
Author(s):  
Eduard Schenuit ◽  
Rainer Bolkart ◽  
Thomas Becker ◽  
Oliver Spinka
Keyword(s):  
Sample Surface ◽  
Measuring System ◽  
Optical Systems ◽  
Correlation Technique ◽  
Digital Cameras ◽  
Compression Tests ◽  
Speckle Correlation ◽  
Optical Strain Measurement ◽  
Optical Strain ◽  
Contact Free

Progresses in developments of high resolution digital cameras and processors power as well enable the use of optical systems for axial and biaxial strain measurements. The main benefit of these systems is a contact free measurement on the sample surface without any influence to the sample. The commonly used optical systems based on following markings attached to sample surface which have to be applied before testing. This paper presents an alternative optical measuring system using the speckle-correlation-technique. The laser based method does not need any special sample markings before testing. The speckle correlation in the presented extensometer measures up to two-dimensional surface strains in tensile as well as in compression tests; original gauge lengths down to 1.5 mm are supported.

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