Surface inspection by an optical triangulation method

Costa, Manuel F. M.

doi:10.1117/1.600840

Cited by 62 publications

(38 citation statements)

References 6 publications

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“…As a complementary technique to monitor morphological changes on the coatings surface and to determine roughness for each coating, an optical triangulation method has also been used [24]. For this purpose, due to surface transparency of the glazed coatings, specimens were previously sputter-coated with an opaque thin film.…”

Section: Morphology and Microstructurementioning

confidence: 99%

“…Fig. 2b represents a closer view of a region in the same coating illustrating two types of cracks perpendicular to each other.Previous studies focusing on the surface analysis of nanocomposite ceramic coatings [25] have reported the effectiveness of microtopography based in laser triangulation [24] by acquisition of information in relative large areas if compared with other methods. In this study, the same technique was employed so the coating surfaces could be inspected and roughness parameters determined.…”

mentioning

confidence: 99%

“…Free-standing coatings were prepared as well so they could be fractured and observed along through-thickness. Specimens with single tracks were also sectioned and polished followed by optical microscopy examination in order to measure the track depths.As a complementary technique to monitor morphological changes on the coatings surface and to determine roughness for each coating, an optical triangulation method has also been used [24]. For this purpose, due to surface transparency of the glazed coatings, specimens were previously sputter-coated with an opaque thin film.…”

mentioning

confidence: 99%

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Morphological and microstructural characterization of laser-glazed plasma-sprayed thermal barrier coatings

Batista

Portinha

Ribeiro

et al. 2006

Surface and Coatings Technology

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Laser-glazing has been revealing a high potential for the improvement of plasma-sprayed (PS) thermal barrier coatings (TBCs) by reducing surface roughness, eliminating open porosity on the surface and generating a controlled segmented crack network, although the relationship of the processing parameters with the resultant properties has not yet been completely established. In this investigation, TBCs consisting of atmospheric plasma sprayed (APS) ZrO 2 -8%wtY 2 O 3 were subjected to a CO 2 continuous wave laser glazing process in order to seal its surface porosity generating an external dense layer. For that purpose, different amounts of radiation resulting from different scanning speeds were applied to the specimens as well as different track overlapping. Results have shown a significant decrease of the surface roughness after the laser treatment. All specimens presented a fully dense and porous free external layer with a polyfaceted columnar microstructure highly adherent to the plasma-sprayed coating. Controlled surface crack networks, extremely dependent on the laser scanning speed and track overlapping, were achieved for each set of processing parameters. The cracks were found to have a tendency to be oriented in two perpendicular directions, one in the direction of the laser beam travel direction, the other perpendicular to it. Moreover, the cracks parallel to the beam moving direction are found to be on the overlapping zone, coinciding with the edge of the subsequent track. The cracks are perpendicular to the surface along the densified layer and tend to branch and deviate from the vertical direction below it, within the porous PS coating. XRD results revealed mainly t' non-transformable tetragonal zirconia with a small percentage of residual monoclinic zirconia for the as-sprayed coating. All glazed coatings presented only t' non-transformable tetragonal zirconia with some variations on preferable crystal orientation. Grain sizes varied from 26 to 52 nm, increasing with an increase of laser irradiated energy, microstrain behaved inversely. Keywords IntroductionThermal barrier coatings (TBCs) have successfully entered service in the turbine section of advanced gas turbine engines in the mid-1970s [1]. Since then, several improvements on the selected materials, processing techniques and life prediction tools have been taking place to contribute for the improvement of TBC's performance as well as for the widening of the field of applications.Current thermal barrier coating systems consist of a bond coat deposited over the material to be protected and then the TBC itself is applied to the bond coat. The metallic bond coat (MCrAlY, M=Ni, Cr or Ni/Cr) acts as a corrosion resistant layer to protect the substrate material (Nickel-based superalloy), forming alumina as the principal protective scale (thermally grown oxide (TGO)). Due to mismatch of thermoelastic properties between the metallic substrate and the ceramic top coat, the bond coat is also necessary to accommodate residual stresses avoiding its...

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Section: Morphology and Microstructurementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Morphological and microstructural characterization of laser-glazed plasma-sprayed thermal barrier coatings

Batista

Portinha

Ribeiro

et al. 2006

Surface and Coatings Technology

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“…The digital image correlation (DIC) method is a noncontact full-field optical deformation measurement technique in which the surface features of the object are traced in digital images. Based on the theory of optical geometry [17], a 2-D DIC system was employed to measure the warpage of a die-attached bare chip Fig. 1(a).…”

Section: Validation Of the Package Deformation Using A Dic Systemmentioning

confidence: 99%

Effect of Die-Bonding Process on MEMS Device Performance: System-Level Modeling and Experimental Verification

Song¹,

Huang²,

Li³

et al. 2009

J. Microelectromech. Syst.

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This paper presents a distributed nodal method (DNM) for compact modeling of the package-device interaction of microelectromechanical systems (MEMS). MEMS devices have movable structures that are sensitive to structural stresses and easily influenced by package structures and environmental parameters. Hence, it is necessary to include the packaged behavior of MEMS into a compact simulation tool with acceptable precision. The conventional nodal method is therefore modified to achieve this purpose. A node with distributed nodal quantities is defined to describe the distributed interactions among the device, package, and environmental temperature. Based on the definition, the related processes of element partition, nodal matrix formation, and element assembly have been demonstrated. The case of a die-bonded microbridge has been used as an example, since the microbridge is not only a typical MEMS structure but also is influenced easily by structural stresses. The DNM model is validated first by a finite-element method (FEM) simulation, then by two individual experiments, including the measurement of die warpage using a digital image correlation system and the detection of shifted natural frequencies of surface-micromachined bridges using a laser Doppler vibrometer system, both after die bonding. The FEM and test results agree with those evaluated by the model with a relative error of less than 10%. Stress alleviation of the test structure has been unintentionally achieved by die bonding, leading to relative shifts of 12%-26% and 19%-26% of the first and third natural frequencies of the microbridges. The packaged behavior also exhibits an evident distributed feature along the die surface as expected. Although, at current stage, the application of the DNM is still limited to static domain, it shows potential in developing hierarchical models of MEMS devices including the package.[ 2007-0256]Index Terms-Die bonding, modeling, nodal analysis, package effect.

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“…Laser based optical triangulation system has been widely applied in industry for measuring distance and also surface profile [1,2]. One of the drawbacks of laser triangulation is it produces speckle and affects measurement uncertainty [3].…”

Section: Introduction (Heading 1)mentioning

confidence: 99%

White light triangulation sensor for flexible inspection system

Tapilouw

Chang

Liu

et al. 2015

2015 9th International Conference on Sensing Technology (ICST)

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A triangulation sensor containing two light sources with different wavelength and individual slit has been developed. Differential technique is applied to improve spatial resolution as performing height reconstruction of a specimen. The system can measure up to 7 mm with accuracy up to 1.144 um. Robotic arm with multiple degrees of freedom can be employed as the motion platform to increase flexibility of inspection.

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Surface inspection by an optical triangulation method

Cited by 62 publications

References 6 publications

Morphological and microstructural characterization of laser-glazed plasma-sprayed thermal barrier coatings

Morphological and microstructural characterization of laser-glazed plasma-sprayed thermal barrier coatings

Effect of Die-Bonding Process on MEMS Device Performance: System-Level Modeling and Experimental Verification

White light triangulation sensor for flexible inspection system

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