Numerical simulation of multiple scattering for modeling speckle roughness analyses on vertical surface regions of silicon wafers

Horváth, Balázs

doi:10.1016/j.ijleo.2005.08.013

Cited by 2 publications

(3 citation statements)

References 5 publications

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“…Optical speckle measurement and analysis techniques have been used to detect strain, 12,13 texturing effects, [14][15][16] and surface roughness. 17,18 While the investigation of such possibilities for MOCVD YBCO tape monitoring is beyond the scope of this manuscript, there is ample incentive to pursue the diagnostic potential of optical speckle measurements in connection with the development of on-line Raman methods for the MOCVD process.…”

Section: Resultsmentioning

confidence: 99%

On-Line Characterization of YBCO Coated Conductors Using Raman Spectroscopy Methods

Maroni

Reeves²,

Schwab³

2007

Appl Spectrosc

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The use of Raman spectroscopy for on-line monitoring of the production of superconducting YBa2Cu3O6+X (YBCO) thin films on long-length metal tapes coated with textured buffer layers is reported for the first time. A methodology is described for obtaining Raman spectra of YBCO on moving tape exiting a metal-organic-chemical-vapor-deposition (MOCVD) enclosure. After baseline correction, the spectra recorded in this way show the expected phonons of the specific YBCO crystal orientation required for high supercurrent transport, as well as phonons of non-superconducting second-phase impurities when present. It is also possible to distinguish YBCO films that are properly textured from films having domains of misoriented YBCO grains. An investigation of the need for focus control on moving tape indicated that focusing of the laser on the surface of the highly reflective YBCO films exiting the MOCVD enclosure tends to produce aberrant photon bursts that swamp the Raman spectrum. These photon bursts are very likely a consequence of optical speckle effects induced by a combination of surface roughness, crystallographic texture, and/or local strain within the small grain microstructure of the YBCO film. Maintaining a slightly out-of-focus condition provides the best signal-to-noise ratio in terms of the obtained Raman spectra. In addition to examining moving tape at the post-MOCVD stage, Raman spectra of the film surface can also be recorded after the oxygen anneal performed to bring the YBCO to the optimum superconducting state. Consideration is given to data processing methods that could be adapted to the on-line Raman spectra to allow the tagging of out-of-specification tape segments and, at a more advanced level, feedback control to the MOCVD process.

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Section: Resultsmentioning

confidence: 99%

On-Line Characterization of YBCO Coated Conductors Using Raman Spectroscopy Methods

Maroni

Reeves²,

Schwab³

2007

Appl Spectrosc

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“…, which can be collected by a digital CCD camera and subsequently analyzed by image processing algorithms (Tay et al . ; Horvath ; Dhanasekar et al . ; Gao and Zhao ).…”

Section: Introductionmentioning

confidence: 99%

“…The reflection and scattering of a coherent laser beam at the optically rough packaging surface, shows a speckle pattern (Barrick 1968; Bass and Fuks 1979;Leader 1979) as shown in Fig. 1, which can be collected by a digital CCD camera and subsequently analyzed by image processing algorithms (Tay et al 1995;Horvath 2006;Dhanasekar et al 2008;Gao and Zhao 2012). This showed, from the different samples of type low-density polyethylene (LDPE), high-density polyethylene (HDPE), biaxial oriented polyamide (BoPA) and BoPP, significant changes due to the influence of a thermal treatment or a high pressure treatment over the surface.…”

Section: Introductionmentioning

confidence: 99%

Laser Speckle Spectroscopy Image Analysis for High Pressure and High Temperature Treatment Discrimination on LDPE, HDPE BOPP, BOPA and PET Polymer Layers Used for Food Packaging

Alvarado

Hussein

Becker

2016

J Food Process Engineering

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The reflection and scattering of a coherent laser beam at the optically rough packaging surface, shows a speckle pattern which can be collected by a digital CCD camera and subsequently analyzed by image processing algorithms. This paper presents an optical laser speckle algorithm for the analysis of the surface roughness of different types of flexible packaging films of low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), biaxial oriented polyamide (BoPA), biaxial oriented polypropylene (BoPP) and polyethylene terephthalate (PET) as a marker to the application of high pressure and high temperature treatments employed in food packaging industry. For every type of polymer, three samples with high pressure treatment of 680 MPa applied for a period of 10 minutes, three samples with high temperature treatment of 90 C applied for a period of 10 minutes and three samples with no treatment application were prepared to ensure structural differences on the polymer surface and the repeatability of the experiments. For the surface analysis, the laser beam was pointed into five different regions (R1 to R5) of every polymer sample analyzed. To ensure a bigger amount of information from the polymer structure, the frame grabber was programmed so that the total acquisition time per region and sample was 5 seconds, at a frame rate of 8.2 pictures per second, generating 41 images per region. A total of 205 speckle images per sample were grabbed and subsequently pre‐processed, cross‐correlated and analyzed. For this purpose, a similarity pattern analysis algorithm was developed, to distinguish among the different treatment classes analyzed (no treatment, high temperature treatment and high pressure treatment). This development takes advantage of the cross‐correlation of intensity curves arising from treatment types. We hypothesize that cross‐correlation coefficients can be exploited to enhance the identification of different treatments types for the different packaging polymers. As shown in the final results, the cross‐correlation coefficient arising from different treatment types were lower than those of intensity curves arising from the same treatment. Remarkable differences were shown in BoPA, where the cross‐correlation coefficient shows big differences between different treatments. These differences between treatments were in the order of 0.980 for the same treatment, 0.742 between nontreated and high‐temperature treatment and 0.388 between nontreated and high pressure treatment. It shows the possibility of using the algorithm investigated as a marker for the discrimination between different treatments on plastics. Practical Application The laser/optical analysis method developed in this investigation, was found to be appropriate for the analysis of the differences in the surface roughness of different flexible packaging films, treated with industrial food conservation methods such as high temperature and high pressure. This investigation gives the possibility of applying an online treatment judgment meth...

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Numerical simulation of multiple scattering for modeling speckle roughness analyses on vertical surface regions of silicon wafers

Cited by 2 publications

References 5 publications

On-Line Characterization of YBCO Coated Conductors Using Raman Spectroscopy Methods

On-Line Characterization of YBCO Coated Conductors Using Raman Spectroscopy Methods

Laser Speckle Spectroscopy Image Analysis for High Pressure and High Temperature Treatment Discrimination on LDPE, HDPE BOPP, BOPA and PET Polymer Layers Used for Food Packaging

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