Application of Fast Fourier Transform (FFT) in Laser Speckle Image Pattern Correlation technique for the metrological measurement

Balamurugan, R.; Muruganand, S.

doi:10.1109/icoac.2012.6416803

Cited by 4 publications

(4 citation statements)

References 11 publications

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“…The finite B of the correlation window limits the spatial resolution and the spectral contents in the displacement field to frequencies of less than 1/B. [11] Result and analysis The desired information retrieved by performing a Fourier-based demodulation. First the image is Fast Fourier transformed (FFT).…”

Section: Fourier Transform Methodsmentioning

confidence: 99%

Laser Speckle Interferometer for Deformation Measurement based on Fast Fourier Transform method

Balamurugan¹

2016

IRA-JTE

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Section: Fourier Transform Methodsmentioning

confidence: 99%

Laser Speckle Interferometer for Deformation Measurement based on Fast Fourier Transform method

Balamurugan¹

2016

IRA-JTE

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“…The cross-correlation approach is suitable for single exposed but multiple images. Laser speckle cross-correlation of two sequential images using FFT algorithm because it is more clear-cut as well as accurate method [10]. Seeded polyurethane granule images are compared successively at short interval time to find the displacements.…”

Section: Image Evaluation By Double Frame Single Exposurementioning

confidence: 99%

Laser speckle image velocimetry by Fast Fourier Transform technique

Balamurugan¹

2022

Laser Phys.

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In this paper, laser image velocimetry, a unique optical method for the velocity measurement of fluid flow has been validated. A laser sheet is illuminated on microscopic seeded particles to produce the speckle pattern at the recording plane. Double frame-single exposure speckle images are captured in such a way that the second speckle image is shifted exactly in a known direction. The auto-correlation method has an ambiguity to identify the direction of flow. To sort out this problem, the partial shift of the second image has been premeditated. Cross-correlation of sub interrogation areas of the speckle patterns is attained by the Fast Fourier Transform technique. Segmented four sub-windows are processed to acquire the velocity information with a vector map precisely.

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“…The displacement distribution of the object surface can be obtained by analyzing the recorded speckle patterns through optical information processing methods, such as the correlation method [10,11] and the Fourier transform method [12,13] . This paper uses Fourier transform for its simplicity and computing efficiency.…”

Section: Double Exposure Speckle Photographymentioning

confidence: 99%

Calibration of Eddy Current Sensor Using Speckle Photography

Zhang

Zhu³

2015

AMM

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Double exposure speckle is proposed to calibrate eddy current sensor in micro-displacement measurement for its simplicity, robustness and high resolution. The specklegram is taken as the vector of the displacement. The actual displacement of an object is calculated according to the speckle displacement on the spatial term, which is worked out according to the fringe spacing on the spectrum surface. A calibration system is proposed with proper speckle size and imaging magnification. Experiments showed that the accuracy of displacement measurement is 0.196um with an optical magnification 65.8. The calibration curve of the eddy current sensor is consistent with the result by a nanopositioning system.

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Application of Fast Fourier Transform (FFT) in Laser Speckle Image Pattern Correlation technique for the metrological measurement

Cited by 4 publications

References 11 publications

Laser Speckle Interferometer for Deformation Measurement based on Fast Fourier Transform method

Laser Speckle Interferometer for Deformation Measurement based on Fast Fourier Transform method

Laser speckle image velocimetry by Fast Fourier Transform technique

Calibration of Eddy Current Sensor Using Speckle Photography

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