A speckle-correlation-based optical lever (SC-OptLev) is constructed for the measurement of small changes in the orientation angle of a surface. The dynamic range of SC-OptLev is found to be twice that of a conventional OptLev for the same experimental configurations. Different filtering mechanisms are implemented, and the correlation results are compared. Two types of computer-automated SC-OptLevs, an open-source-based computing system with a low-cost image sensor and a commercial computing system, are presented with assistive computational modules. © 2019 Optical Society of America

Shanti Bhattacharya

Department of Electrical Engineering

Anand Vijayakumar

D. Jayavel

M. Muthaiah

Costs

Open systems

Speckle

Computing system

Dynamic range

EXTENDED DYNAMIC RANGES

FILTERING MECHANISM

Open sources

OPTICAL LEVER

Orientation angles

SPECKLE CORRELATIONS

Optical correlation

Fulltext

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IIT Madras

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

Applied Optics

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. © 2019, The Author(s).

Scientific Reports

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

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

Journal	Data powered by TypesetApplied Optics
Publisher	Data powered by TypesetOSA - The Optical Society
ISSN	1559128X
Impact Factor	1.230
Open Access	Yes
Citation Style	unsrt
Sherpa RoMEO Archiving Policy	Green