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Journal ArticleDOI

Use of two wavelengths in microscopic TV holography for nondestructive testing

01 Nov 2014-Optical Engineering (International Society for Optics and Photonics)-Vol. 53, Iss: 11, pp 110501-110501

Abstract: Single wavelength TV holography is a widely used whole-field noncontacting optical method for nondestructive testing (NDT) of engineering structures. However, with a single wavelength configuration, it is difficult to quantify the large amplitude defects due to the overcrowding of fringes in the defect location. In this work, we propose a two wavelength microscopic TV holography using a single-chip color charge-coupled device (CCD) camera for NDT of microspecimens. The use of a color CCD allows simultaneous acquisition of speckle patterns at two different wavelengths and makes the data acquisition as simple as that of the single wavelength case. For the quantitative measurement of the defect, an error compensating eight-step phase-shifted algorithm is used. The design of the system and a few experimental results on small-scale rough specimens are presented.
Topics: Nondestructive testing (58%), Holography (54%), Speckle pattern (54%)
Citations
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Journal ArticleDOI
TL;DR: The recent advances in multi-colour interferometric techniques and their demanding applications for characterization of micro-systems, non-destructive testing, and bio-imaging applications are reviewed.
Abstract: Interferometry has been widely used for optical metrology and imaging applications because of their precision, reliability, and versatility. Although single-wavelength interferometery can provide high sensitivity and resolution, it has several drawbacks, namely, it fails to quantify large-discontinuities, large-deformations, and shape of unpolished surfaces. Multiple-wavelength techniques have been successfully used to overcome the drawbacks associated with single wavelength analysis. The use of colour CCD camera allows simultaneous acquisition of multiple interferograms. The advances in colour CCD cameras and image processing techniques have made the multi-colour interferometry a faster, simpler, and cost-effective tool for industrial applications. This article reviews the recent advances in multi-colour interferometric techniques and their demanding applications for characterization of micro-systems, non-destructive testing, and bio-imaging applications.

19 citations


Cites background or methods from "Use of two wavelengths in microscop..."

  • ...Using the phases at multiple wavelengths, the unambiguous step-height measurement of single-wavelength interferometry can be extended in two ways: (a) Phase subtraction method [42, 58, 73], and (b) Fringe order method [41, 48, 60]....

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  • ...Two-wavelength speckle fringe analysis for quantifying large defects was demonstrated [60, 102]....

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  • ...defects and also it can provide the shape of the test object at effective wavelength [60, 102]....

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  • ...Several configurations have been reported with colour CCD cameras : 2λ-interferometry with a 1-CCD[47, 60], 3λ-interferometry with 1-CCD [48]and 3-CCD[49], and white light interferometry with 1-CCD [50, 53, 78]and 3-CCD[49, 63]....

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  • ...The Bayer filter 1-CCD RGB camera has been demonstrated for surface profiling of large discontinuities[23, 51, 58, 59], and simultaneous measurement of shape and deformation[23, 48], non-destructive testing (NDT) of large defects[60], simultaneous acquisition of blood flow, blood volume, and oxygenation on human fingers using dualwavelength laser imaging [61]etc....

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Journal ArticleDOI
Congcong Lv1, Kaifu Wang1, Guoqing Gu, Yun Pan1Institutions (1)
Abstract: In this paper, a new method, Moment-Stiffness Method (MSM), is proposed for measuring the edge and depth of internal defects which can be applied to any structures with known stiffness. MSM is based on the relation of the differences of displacements between flawed and flawless areas caused by the change of stiffness. Theoretical, numerical and experimental results are presented. In the method, digital speckle pattern interferometry (DSPI) is used to measure the out-of-plane displacement of a plate with an internal defect. In the detection of the first specimen, the distributions of first- and second-order radial derivatives of the out-of-plane displacement are obtained by the radial numerical differential. Then the full edge and depth of the defect is accurately determined using MSM. All the results indicate that the proposed method is an effective tool to measure internal defects precisely.

10 citations


Proceedings ArticleDOI
01 Mar 2019-
Abstract: Interferometry has been widely used for surface metrology because of their precision, reliability, and versatility. Although monochromatic-light interferometery can provide high sensitivity and resolution, but it fails to quantify largediscontinuities. Multiple-wavelength techniques have been successfully used to extend the unambiguous step height measurement rage of single wavelength interferometer. The use of RGB CCD camera allows simultaneous acquisition of fringes generated at different wavelengths. In this work, we discuss details about the fringe analysis of white light interferograms acquired using colour CCD camera. The colour image acquired using RGB camera is decomposed in to red, green, blue components and corresponding interference phase is measured using phase evaluation algorithms. The approach makes the 3D surface measurements faster, cost-effective for industrial applications.

2 citations


Proceedings ArticleDOI
04 Mar 2019-
TL;DR: Various phase shifting algorithms, and their tolerance for phase shift error are discussed, and the applications of higher-order phased shifting algorithms will be presented, useful for multiple-wavelength and white light interferometry where more than one wavelength is used for optical phase measurements.
Abstract: Multiple-wavelength interferometric techniques have been successfully used for large step-height and large deformation measurements. Also it could resolve the step height between smooth and rough surfaces which is not possible with single wavelength interferometry. Temporal phase shifting algorithm, which requires a phase shifter such as PZT, has been widely used for accurate phase evolution in interferometry. The phase shifter needs to be calibrated at every wavelength if multiple wavelengths are used for measurement, it is a time consuming process. If phase shifter is not calibrated accurately, it can introduce phase shift errors. In this work, we will discuss various phase shifting algorithms, and their tolerance for phase shift error. And the applications of higher-order phased shifting algorithms will be presented. The study is useful for multiple-wavelength and white light interferometry where more than one wavelength is used for optical phase measurements.

2 citations


Cites background or methods from "Use of two wavelengths in microscop..."

  • ...This approach was successfully implemented in single wavelength [4], two-wavelength [20-23], three-wavelength [24, 25], white light interferometry [17, 26-30], etc....

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  • ...The algorithms 3, 4a provide zero tolerance, on the other hand 8-step algorithm shows maximum ±20% tolerance [21, 24, 25]....

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Proceedings ArticleDOI
14 Feb 2020-
Abstract: Digital speckle pattern interferometry (DSPI) has been widely used for surface metrology of optically rough surfaces. Single visible wavelength can provide high measurement accuracy, but it limits the deformation measurement range of the interferometer. Also, it is difficult to reveal the shape of a rough surface with one wavelength in normal illumination and observation geometry. Using more than one visible wavelength in DSPI, one can measure large deformations as well as shape using synthetic wavelength approach. In this work, we will discuss multi-wavelength speckle pattern interferometry using a Bayer RGB sensor. The colour sensor allows simultaneous acquisition of speckle patterns at different wavelengths. The colour images acquired using RGB sensor is split in to its individual components and corresponding interference phase map is recovered using error compensating phase shifting algorithm. The wrapped phase is unwrapped to quantify the deformation or shape information of the sample under inspection. Theoretical background of RGB interferometry for deformation and shape measurements, and experimental results will be presented.

1 citations


References
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Journal ArticleDOI
C Polhemus1Institutions (1)
01 Sep 1973-Applied Optics
TL;DR: An extension of the static technique to real- time dynamic testing is proposed and an operational variable-sensitivity interferometer utilizing the real-time technique is described.
Abstract: Previous methods of two-wavelength variable-sensitivity interferometry are reviewed and a simplified two-wavelength technique for interferometric testing under static conditions is discussed. An extension of the static technique to real-time dynamic testing is proposed and an operational variable-sensitivity interferometer utilizing the real-time technique is described.

224 citations


Journal ArticleDOI
Abstract: From the Publisher: Digital Speckle Pattern Interferometry (DSPI) is the generic name for a class of important interferometric techniques such as TV holography, electronic holography or phase shifting pattern interferometry, all of which involve similar optical and electronic principles. These techniques are increasingly used in a wide range of fields including experimental mechanics, vibration analysis and non-destructive testing. Digital Speckle Interferometry and Related Techniques provides a single source of information in this rapidly progressing field. Containing contributions from leading experts, it provides the key background information, including the fundamental concepts, techniques, and applications, and presents the major technological progress that has contributed to revitalization in the field over the past fifteen years, including digital speckle photography and digital holographic interferometry. This is an invaluable text for practising engineers in industry and research institutes, and academic and development researchers in scientific and engineering disciplines who use, or are interested in, DSPI. This title would also be of interest to teachers and final year undergraduate/postsgraduate students of physics, optics, experiemental mechanics, photomechanics, optical metrology, engineering metrology, and non-destructive testing.

102 citations


Journal ArticleDOI
Min Suk Kim1, Toralf Scharf1, Christoph Menzel2, Carsten Rockstuhl2  +1 moreInstitutions (2)
27 Feb 2012-Optics Express
TL;DR: Detailed analysis of the impact and the interplay of various diffraction orders to the formation of Talbot images provides new insights into the fundamental properties of gratings that often find use in applications such as, e.g., lithography, sensing, and imaging.
Abstract: By means of experiment and simulation, we achieve unprecedented insights into the formation of Talbot images to be observed in transmission for light diffracted at wavelength-scale amplitude gratings. Emphasis is put on disclosing the impact and the interplay of various diffraction orders to the formation of Talbot images. They can be manipulated by selective filtering in the Fourier plane. Experiments are performed with a high-resolution interference microscope that measures the amplitude and phase of fields in real-space. Simulations have been performed using rigorous diffraction theory. Specific phase features, such as singularities found in the Talbot images, are discussed. This detailed analysis helps to understand the response of fine gratings. It provides moreover new insights into the fundamental properties of gratings that often find use in applications such as, e.g., lithography, sensing, and imaging.

66 citations


Journal ArticleDOI
Abstract: In laser based interferometry, the unambiguous measurement range is limited to half a wavelength. Multiple wavelength or white light interferometer is used to overcome this difficulty. In this paper a white light interferometer with a colour CCD camera is discussed. We access interference intensity information from the three channels of the colour CCD simulating three-wavelength measurement. This makes the data acquisition as simple as in single wavelength interferometry. The unambiguous measurement range however gets limited by the coherence length of the CCD. The usefulness of the proposed method is demonstrated on a micro-sample.

48 citations


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