Measurement of nanometric displacements by correlating two speckle interferograms

Tendela, Lucas P.; Galizzi, Gustavo E.; Federico, Alejandro; Kaufmann, Guillermo H.

doi:10.1364/ao.50.001758

Cited by 16 publications

(3 citation statements)

References 5 publications

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“…where C P the Pearson's correlation coefficient between the two interferograms and the operator is evaluated over a sliding window of size L × L on each recorded image [27]. The introduction of two approximations overcomes limitations of applicability and achieve higher accuracy [23]: (1) the influence of the intensity bias in the correlation coefficient can be ignored, (2) the modulation term in Eq.…”

Section: A2 Correlation Of Imagesmentioning

confidence: 99%

Comparative analysis of nanometric inspection methods in fringeless speckle pattern interferometry

et al. 2017

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In digital speckle pattern interferometry, fringeless speckle pattern interferograms are obtained when the object field deformation is insufficient to produce local phase variations higher than 2π. Therefore, the use of the well-known phase recovery algorithms based on fringe processing is not adequate. In this work, distinct algorithms based on the application of a straightforward arccosine function to a filtered interferogram and the correlation of intensity images and implicit smoothing splines are proposed, analyzed, and compared for the fast inspection of nanometric displacement fields, avoiding the acquisition of several images. In addition, three different methods for the normalization of fringeless speckle pattern interferograms are proposed. The Structural Similarity Index is used to assess the performance of the tested methods by means of numerical simulations under different illuminations, signal-to-noise ratios, phase excursions, and mean speckle size conditions. The analysis shows that the phase recovered by the methods based on the arccosine function and correlation are appropriate for a fast inspection solution. The implicit smoothing spline outperforms other methods in almost all conditions.

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Section: A2 Correlation Of Imagesmentioning

confidence: 99%

Comparative analysis of nanometric inspection methods in fringeless speckle pattern interferometry

et al. 2017

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“…Electronic speckle pattern interferometry (ESPI) (Muravski & Fit'o, 2005;Tendela, Galizzi, Federico, & Kaufmann, 2011) records the intensity images of speckle patterns produced on rough surfaces in load and unloaded state. The fringe pattern is obtained by subtracting the intensity images and applying phase shifting procedure to determine the displacement.…”

Section: Introductionmentioning

confidence: 99%

Contouring reflective plates along a curved strip using the intensity integration technique: Experimentation and simulation

Vijaya

Subramanian

Lakshmipriya

2017

Journal of Applied Research and Technology

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The intensity integration technique (IIT) is one of the simplest intensity-based image processing techniques used to determine the deformation field of a reflective specimen (1D or 2D) under loaded conditions. It works on the energy conservation principle. The total quantity of light that falls on the specimen, before and after loading it, is assumed to be the same, and hence, the integrated (cumulative) intensity is used as a correlation parameter to find the change in position of any point from one state to the other. Because the cumulative intensity is unidirectional, it is simple to apply IIT on the one-dimensional object. This work aims to apply IIT on the curved strip to find the deformation field of centrally loaded clamped plates along that stripe. The experimental results are compared with the numerical solution. Simulation is done to mimic the behavior of the several types of curved strips (grid pattern) at various positions for different loading conditions based on one-to-one mapping of finite element (FE) models with experimental images.

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“…The interferometry methods, including Fabry-Perot cavities and Mach-Zehnder interferometers, have complicated structures and high precision fabrication requirements [ 9 , 10 , 11 ]. In the correlation method, the traditional cross-correlation (TCC) is often used to process the output signals of two identical sensors in the measured region [ 12 , 13 , 14 ], which provides non-contact measurements with low cost for monitoring gas-solid and solid-liquid flows [ 15 , 16 , 17 , 18 ]. The image matching method, in which a high-speed camera captures a series of instantaneous images to calculate velocity, also belongs to the correlation methods [ 19 , 20 , 21 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

Remote Evaluation of Rotational Velocity Using a Quadrant Photo-Detector and a DSC Algorithm

Zeng

Zhu

Yang

2016

Sensors

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This paper presents an approach to remotely evaluate the rotational velocity of a measured object by using a quadrant photo-detector and a differential subtraction correlation (DSC) algorithm. The rotational velocity of a rotating object is determined by two temporal-delay numbers at the minima of two DSCs that are derived from the four output signals of the quadrant photo-detector, and the sign of the calculated rotational velocity directly represents the rotational direction. The DSC algorithm does not require any multiplication operations. Experimental calculations were performed to confirm the proposed evaluation method. The calculated rotational velocity, including its amplitude and direction, showed good agreement with the given one, which had an amplitude error of ~0.3%, and had over 1100 times the efficiency of the traditional cross-correlation method in the case of data number N > 4800. The confirmations have shown that the remote evaluation of rotational velocity can be done without any circular division disk, and that it has much fewer error sources, making it simple, accurate and effective for remotely evaluating rotational velocity.

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Measurement of nanometric displacements by correlating two speckle interferograms

Cited by 16 publications

References 5 publications

Comparative analysis of nanometric inspection methods in fringeless speckle pattern interferometry

Comparative analysis of nanometric inspection methods in fringeless speckle pattern interferometry

Contouring reflective plates along a curved strip using the intensity integration technique: Experimentation and simulation

Remote Evaluation of Rotational Velocity Using a Quadrant Photo-Detector and a DSC Algorithm

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