- Email: [email protected]
Dynamic holographic-electronic speckle-pattern interferometry
N DT Abstracts silicon substrate were characterized through impulsive stimulated thermal scattering (ISTS). The lowest-order pseudo-Rayleigh acoustic mode of the film was excited and monitored optically. From the measured acoustic phase velocities, the elastic meduli of the film were determined. The ISTS technique also permits measurements of the CNsub(x) thermal diffusivity. The noninvasive optical measurements described can provide a useful guide to refinements in thin film fabrication procedures and for optimization of mechanical and thermal transport properties. 57000 Dubois,M.; Enguehard, F.; Choquet, M.; Monchalin, J.P.; Bertand, L. Photoacoustic spectrometry applied to graphite-epoxy laminates Review o f Progress in Quantitative Nondestruction Evaluation, Brunswick, Maine (United States), I-6 Aug. 1993. Vol. 13A, pp. 441- 448. Edited by D.O. T h o m p s o n and D.E. Chimenti. Plenum Press (1994) ISBN 0-306-44731-2 In this paper, we present results of Fourier Transform Infrared PhotoAcoustic Spectroscopy (FTIR-PAS) of graphite-epoxy laminates. FTIR-PAS seems to he an interesting technique that can adequately provide absolute values of the optical absorption spectrum of composites. Three optical penetration spectra, derived from the same experimental signal using three different data processing methods, are presented and compared. These spectra are also compared to a spectrum of a cured epoxy resin so that one can better understand the optical absorption process within a graphite-epoxy laminate. We also present an analytical model of the photoacoustic signal for a two layer system. 56539 Scaman,M.E.; Economikos, L.; Lambright, J. Computer vision for automatic inspection of a high density grid of pads on m u l t i - c h i p m o d u l e s (MCM-D) IEEE Transactions on Components, Packaging, and Manufacturing Technology-Part B, Vol. 17, No. 3, pp. 291-299 (Aug.1994) Computer vision techniques have been developed and implemented for automatic optical inspection (AOI) of multi-chip modules with thin films. A case study, detailing the application of the techniques based on an Orbot TFS01 visual inspection system platform for a high density grid of circular pads, is presented. The techniques presented here are capable of detecting electrical and non-electrical defects such as near shorts, wrong metallurgy, contamination, etc.
May, R.G.; Sanderson, J.M.; Claus, R.O. Combined f i b e r o p t i c s t r a i n s e n s o r a n d c o m p o s i t e c u r e monitor for s m a r t s t r u c t u r e a p p l i c a t i o n s 56531
Smart Sensing and Materials 1994. Smart Sensing, Processing, and Instrumentation, Orlando, Florida (United States), 14-16 Feb. 1994. pp. 46-57. Edited by J.S. Sirkis, SPIE Vol. 2191 (1994) 1SBN 0-8194- 1486-7 An adaptation of an extrinsic Fabry-Perot interferometer (EFPI) strain sensor is described, which permits the state of cure of an epoxy matrix to be monitored, when the sensor is embedded in a polymeric matrix composite. By using a glass rod with a retroreflecting end of the target fiber in the EFPI sensor, the intensity of the light reflected depends on the refractive index of the host matrix, if a low coherence source is used. As the epoxy cross-links during cure, the refractive index of the epoxy will increase to a value exceeding that of the target fiber. The resulting increased loss in the fiber can be detected at the sensor output and correlated to the state of cure of the epoxy. After cure, the sensor may be operated as a conventional EFPI strain sensor if a coherent source is used. 56530 Lou, K.A. Combined sensor system for process and in-service health monitoring of c o m p o s i t e s t r u c t u r e s Smart Structures and Materials 1994. Smart Sensing, Processing, and Instrumentation, Orlando, Florida (United States), 14-16 Feb. 1994. pp. 32-45. Edited by J.S. Sirkis, SPIE Vol. 2191 (1994) ISBN 0-8194- 1486-7 This paper describes an approach which integrates an optical fiber lime domain strain and temperature monitoring network with a fiber optic (FO) cure monitoring system for composite materials. The proof-of- concept tests consisted of fabricating a thermoset composite laminate which combined a multi-segment optical fiber sensor network, monitoring the state of cure during the fabrication of the laminate, and determining strain and temperature during tests performed after fabrication. Software was written to interface a commercially available Optical Time Domain Reflectometer (OTDR) system to a personal computer.
134
56527 Shalygin, V.A.; Shturbin, A.V.; Antyushin, V.S. Local n o n d e s t r u c t i v e testing of the parameters of plates and epitaxial layers of Cdsub(x)Hgsub(l-x)Te Russian Journal o f Nondestructive Testing, Vol. 29, No. 10, pp. 781- 792 0 u n . 1994) A method of determining the parameters of solid solutions of Cdsub(x)Hgsub(I-x)Te based on an analysis of the optical-transmission spectra at room temperature is developed. The method is realized in practice using an automatic spectrophotorneter which gives high spatial resolution when probing the specimens. Investigations are made of the nonuniformities in plates and epitaxial films of Cdsub(x)Hgsub(l-x)Te. For a spatial resolution of 400 p.m an accuracy in determining the local values of the composition Ax = + 0.0005 (for plates) and Ax = :t: 0.001 (for epitaxial layers) can be achieved. For plates of p-Cdsub(x)Hgsub(l-x)Te when determining the hole density due to impurities and lattice defects, an accuracy of &p (77 K) "="+ 10sup(I 5) cmsup(-3) is achieved. The method can also be employed to monitor nonuniformities in the distribution of free electrons in plates of n-Cdsub(x)Hgsub(l-x)Te. 55621 Fildes,J.M.; Milkovich, S.M.; Altkorn, R.; Haidle, R., Neatrour, J. In situ infrared spectroscopy and neural network analysis for c o m p o s i t e c u r e monitoring Advanced Materials: Expanding the Horizons. 25th International S A M P E Technical Conference, Philadelphia, Pennsylvania (United States), 26-28 Oct. 1993. Vol. 25, pp. 887-900. Edited by R. Trabocco and T. Lynch, S A M P E (1993) We describe the development of a novel optical fiber based infrared spectroscopic sensor for in situ cure monitoring of prepreg layups, and use of neural networks to directly extract state of cure and other process control information from the spectra data. The sensor is fabdeated from fluoride glass optical fibers, and used to collect infrared spectra of curing epoxy in the wavelength range of 1.7 to 5 microns. Spectroscopic sensors, along with more conventional sensors such as thermocouples and refractive index sensors, were inserted into prepreg layups and cured in a heated vacuum bag or an autoclave. The refractive index sensor was used to provide a reference measurement of the cure state. Unsupervised learning neural network analysis was used to determine the number of states of cure that existed during processing. For each state of cure, supervised learning was used to develop neural network models of refractive index (i.e. degree of cure) and temperature. 55370 Lappalainen, T. A u t o m a t e d image analysis method for the detection of c r a c k s on wood s u r f a c e (in Finnish) Valtion Teknillinen Tutkimuskeskus, Espoo (Finland), N9417542/9/GAR, 97 pp. (Jan. 1992) An automated image analysis method was developed for the inspection of cracks on wood surfaces and on paint films. The system is capable of both detecting and analyzing the cracks. The automatic method is capable of classifying the average size of the cracks and the quantity of cracking on the scale 0 to 5 (ISO (International Standards Organization) 4628 standard) with an accuracy of 4-/- I compared to visual classification. The inspection algorithms are based on morphological preprocessing and statistical crack recognition. For optimal thresholding, an experimental system was developed. The image acquisition part of the system is based on a monochrome CCD (Charge Coupled Device) matrix camera. 54787 Furukawa, J.; Furuya H.; Shingyouji, T. Detection of bulk microdefects underneath the surface of Si wafer using infrared light s c a t t e r i n g tomography Japanese Journal o f Applied Physics, Pt. 1. Vol. 32, No. I IA, pp. 5178- 5179 (Nov. 1993) A new method has been developed to detect bulk micredefects (BMD) underneath the surface of a Si wafer using infrared light scattering tomography. In this method, infrared light enters from the cleaved surface obliquely and is totally reflected at the surface of the wafer, in order to eliminate the effect of scattering at the surface. BMD not only underneath the surface of the polished silicon wafer, but also underneath the wafer surface on which devices are fabricated, are easily detected by this method. 54241 Ahmadshahi, M.A.; Krishnaswamy, S.; Nemat-Nasser, S. Dynamic holographic-electrunic speckle-pattern interferometry Journal o f Applied Mechanics, Vol. 60, No. 4, pp. 866-874 (Dec. 1993) development of a nondestructive, full-field, quantitative optical technique, and its feasibility to study dynamic deformations of opaque and diffusively reflecting solids under transient loads, are discussed. The technique involves recording a sequence of dynamically changing two-heam
N DT Abstracts
speckle interference patterns (also called holographic speckle patterns) of a rapidly deforming body which is doubly illuminated by a laser light source. The time sequence of speckle icatterns is recorded by means of a high-speed camera on an ultra-sensitive 3~:-mm film. The developed negatives are then digitized by a CCd camera into an image processing system.
52024 Steckenrider, J.C.; Wagner, J.W. C o m p u t e d speckle decorrelation (CSD) a n d its application for fatigue d a m a g e monitoring Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 28 Jul.-2 Aug. 1991. Vol. I IA, pp. 487-494. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1992) Non-contact surface deformation analysis and mapping can be conducted using a video-based laser speckle technique, at speeds approaching video frame rates. The technique, known as Computed Speckle Decorrelation (CSD), uses the speckle decorrelation associated with surface deformation. CSD means that faster and more quantitative analysis of the progression of fatigue damage in thick graphite/epoxy composite materials is now possible, than was previously available using film-based techniques. CSD combines speckle decorrelation work with real time computer techniques. This study used CSD to monitor fatigue degradation in 2024-T4 aluminium, subjected to reverse bending fatigue.
54054 Fanton, J.T.; Opsal, J.; Willenborg, D.L.; Kelso, S.M.; Rosencwaig, A. Beam profile refiectometry: a new technique for thin film measurement Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 19-24 Jul. 1992. Vol. 12A, pp. 387-394. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1993). ISBN 0-306-44483-6. The information present in the intensity profile of a highly focussed, linearly polarized beam makes the BPR a powerful film measurement technique. The shape and amplitude information in the $ and P profiles of angular reflectivity enable us to determine not only the thickness of a simple film, but also the refractive index, extinction coefficient or even the thicknesses of other films in a multi-layer stack. These measurements all occur in a submicron area making possible measurements on product wafers.
50521 Radha, T.S.; Ramprasad, B.S. M e a s u r e m e n t of the t h e r m a l stress in specularly reflecting thin films using real-time holographic i n t e r f e r o m e t r y Nondestructive Testing and Evaluation, Vol. 8-9, Pt. 2, (1992) Proceedings of the 5th International Symposium on Nondestructive Characterization of Materials, Karuizawa (Japan), 27-30 May 1991. pp. 949-957. Edited by T. Kishi, T. Saito, C, Ruud, and R. Green. In this paper a method of measurement of thermal stress of thin films using real-time holographic interferometry is described, with particular emphasis on specularly reflecting thin films. A few thin film-substrate systems have been used for the measurements. For the copper film on brass substrate and silver on glass theoretical and experimental results are found to agree reasonably well at different temperatures. For the cases of aluminium film and magnesium fluoride film on glass there is a wide discrepancy. However it is pointed out that experimental values are closer to reality.
53807 Ehrlich, M.I.; Stec~[enrider, J.S.; Wagner, J.W. High speed holographic " c i n e m a t o g r a p h y " with f r a m e rates a p p r o a c h i n g 25 nanosecon~ds lntefferometry Applications. Proceedings of Meeting at San Diego, California (United States), 22-23 Jul. 1992. pp. 270-276. Edited by R.J. Pryutriewicz, G.M. Bacon and W.P.C Juptner. SPIE. Vol. 1756 (1993) ISBN 0-8194-0929-4 A holographic recording system has been developed in which a single pulse from a frequency doubled Nd:YAG laser is repeatedly spit and delayed to provide up ~ 10 pulses which are separated both in time and in space. A custom graded beam splitter is used to help insure near equal amplitude of all ten pulses. A White cell provides adjustable delay between the sequential outputs of tbe system over a range from 28 to 170 nanoseconds. By appropriate design of the holographic recording geometry, up to ten distinct holographic frames may be recorded in sequence on a single 4" x 5" film plate. Using the system, studies have been performed on the dynamics of detonation of 100 micron explosive particles and on the acceleration and growth of cracks in brittle materials. CW reconstruction of each holographic frame permits microscopic examination of the reconstructed images so that precise measurements of shock front or crack length may be made as a function of time.
50270 Yamaguchi, I.; Takemori, T.; Kobayashi, K. Biaxiai laser speckle strain gauge (In Japanese: English Abstract) Journal of JSNDI, Vol. 39, No. 8, pp. 682-686 (Aug. 1990) The laser speckle stain gauge, which measures surface strain in a noncontacting and automatic way by optoelectronically detecting and comparing speckle displacements at two symmetrical scattering angles, has been extended to a biaxial configuration, lnplane strains along the orthogonal directions have been measured by using four linear image sensors and high speed correlators with the sensitivity of a few tens of microstrains and a time response of a hundred Hz. The instrument has also been applied to simple and quick determination of Poisson's ratio of polymer films at various loading frequencies.
53804 Dovgalenko, G.Y.; Kadura, S.A. Application of hiologicall p h o t o p o l y m e r to nondestructive testing Interferometry Applications Proceedings of Meeting at San Diego, California (United States), 22-23 Jul. 1992. pp. 227-232. Edited by R.J. Pryutriewicz, G.M. Bacon and W.P.C Juptner. SPIE. Vol. 1756 (1993) 1SBN 0-8194-0929-4. The present paper com;iders the results of investigation of photopolymeric films "Biochea~n" as a reversible media to dynamical holographic interferometry. The optimized condition to writing-readout of hologram were obtained. The n=,sultsof nondestructive testing of materials based on adaptive bolographic interferometer using "Biochrom" are presented.
50268 Musilova,J.; Ohlidal, I. Influence of defects of thin films on d e t e r m i n i n g t h e i r thickness by the method based on white light interference Journal of Physics D. Applied Physics, Vol. 25, No. 7, pp. i 131-1138 (14 Jul. 1992) The usefulness of the thin film thickness determination method based on the principle of white light interference could he limited not only by parameters characterizing the optical system itself (optical constants of the measured and reference systems, the measured thickness of the thin film of interest) but also by other additional effects such as inhomogeneity of optical constants of the measured film, roughness of the boundaries and the existence of surface or interface layers. These effects are discussed.
52779 Radha, T.S; Rampr,~sad, B.S M e a s u r e m e n t of the t h e r m a l stress in specularly reflecting thin films using real-time holographic i n t e r f e r o m e t r y Nondestructive Characteri;,ation of Materials V, Karuizawa (Japan), 27- 30 May 1991. pp 949-957. Edited by T. Kishi, T. Saito, C. Ruud and R. Green. Iketani Science and Technology Foundation (1993) A method of measurement of thermal stress of thin films using real-time holographic intefferometry is described, with particular emphasis on specolarly reflecting thin films. A few thin film-substrate systems have been used for the measurements. For the copper film on brass substrate and silver on glass theoretical and experimental results are found to agree reasonably well at different temperatures. For the cases of aluminium film and magnesium fluoride film on gla,gsthere is a wide discrepancy. However it is pointed out that experimental values are closer to reality.
Bonniau, P.; Chazelas, J.; Lecuellet, J.; Gendre, F.; Turpin, M.; Le Pesant, J.-P.; Brevignon, M. 50002
Damage
detection
in
woven-composite
materials
using
embedded fiber optic sensors Fiber Optic Smart Structures and Skins IV, Massachusetts, Boston (United States), 5-6 Sep. 1991. pp. 52-63. Vol. 1588. SPIE (1991) This paper presents our preliminary results on the use of fiber optic sensors for impact detection on Kevlar-opoxy panels. Interfero- polarimetric measurements have been performed by using two different kinds of polarisation-maintaining optical fibers. The sensitivity of the fibers to internal process stresses and to external impact stresses is discussed with respect to the coating nature. The effect of an over-coating on the fiber sensitivity is also reported, impact-induced delaminations have been observed and the optical response has been adjusted by using an appropriate over-coating.
135
May, R.G.; Sanderson, J.M.; Claus, R.O. Combined f i b e r o p t i c s t r a i n s e n s o r a n d c o m p o s i t e c u r e monitor for s m a r t s t r u c t u r e a p p l i c a t i o n s 56531
Smart Sensing and Materials 1994. Smart Sensing, Processing, and Instrumentation, Orlando, Florida (United States), 14-16 Feb. 1994. pp. 46-57. Edited by J.S. Sirkis, SPIE Vol. 2191 (1994) 1SBN 0-8194- 1486-7 An adaptation of an extrinsic Fabry-Perot interferometer (EFPI) strain sensor is described, which permits the state of cure of an epoxy matrix to be monitored, when the sensor is embedded in a polymeric matrix composite. By using a glass rod with a retroreflecting end of the target fiber in the EFPI sensor, the intensity of the light reflected depends on the refractive index of the host matrix, if a low coherence source is used. As the epoxy cross-links during cure, the refractive index of the epoxy will increase to a value exceeding that of the target fiber. The resulting increased loss in the fiber can be detected at the sensor output and correlated to the state of cure of the epoxy. After cure, the sensor may be operated as a conventional EFPI strain sensor if a coherent source is used. 56530 Lou, K.A. Combined sensor system for process and in-service health monitoring of c o m p o s i t e s t r u c t u r e s Smart Structures and Materials 1994. Smart Sensing, Processing, and Instrumentation, Orlando, Florida (United States), 14-16 Feb. 1994. pp. 32-45. Edited by J.S. Sirkis, SPIE Vol. 2191 (1994) ISBN 0-8194- 1486-7 This paper describes an approach which integrates an optical fiber lime domain strain and temperature monitoring network with a fiber optic (FO) cure monitoring system for composite materials. The proof-of- concept tests consisted of fabricating a thermoset composite laminate which combined a multi-segment optical fiber sensor network, monitoring the state of cure during the fabrication of the laminate, and determining strain and temperature during tests performed after fabrication. Software was written to interface a commercially available Optical Time Domain Reflectometer (OTDR) system to a personal computer.
134
56527 Shalygin, V.A.; Shturbin, A.V.; Antyushin, V.S. Local n o n d e s t r u c t i v e testing of the parameters of plates and epitaxial layers of Cdsub(x)Hgsub(l-x)Te Russian Journal o f Nondestructive Testing, Vol. 29, No. 10, pp. 781- 792 0 u n . 1994) A method of determining the parameters of solid solutions of Cdsub(x)Hgsub(I-x)Te based on an analysis of the optical-transmission spectra at room temperature is developed. The method is realized in practice using an automatic spectrophotorneter which gives high spatial resolution when probing the specimens. Investigations are made of the nonuniformities in plates and epitaxial films of Cdsub(x)Hgsub(l-x)Te. For a spatial resolution of 400 p.m an accuracy in determining the local values of the composition Ax = + 0.0005 (for plates) and Ax = :t: 0.001 (for epitaxial layers) can be achieved. For plates of p-Cdsub(x)Hgsub(l-x)Te when determining the hole density due to impurities and lattice defects, an accuracy of &p (77 K) "="+ 10sup(I 5) cmsup(-3) is achieved. The method can also be employed to monitor nonuniformities in the distribution of free electrons in plates of n-Cdsub(x)Hgsub(l-x)Te. 55621 Fildes,J.M.; Milkovich, S.M.; Altkorn, R.; Haidle, R., Neatrour, J. In situ infrared spectroscopy and neural network analysis for c o m p o s i t e c u r e monitoring Advanced Materials: Expanding the Horizons. 25th International S A M P E Technical Conference, Philadelphia, Pennsylvania (United States), 26-28 Oct. 1993. Vol. 25, pp. 887-900. Edited by R. Trabocco and T. Lynch, S A M P E (1993) We describe the development of a novel optical fiber based infrared spectroscopic sensor for in situ cure monitoring of prepreg layups, and use of neural networks to directly extract state of cure and other process control information from the spectra data. The sensor is fabdeated from fluoride glass optical fibers, and used to collect infrared spectra of curing epoxy in the wavelength range of 1.7 to 5 microns. Spectroscopic sensors, along with more conventional sensors such as thermocouples and refractive index sensors, were inserted into prepreg layups and cured in a heated vacuum bag or an autoclave. The refractive index sensor was used to provide a reference measurement of the cure state. Unsupervised learning neural network analysis was used to determine the number of states of cure that existed during processing. For each state of cure, supervised learning was used to develop neural network models of refractive index (i.e. degree of cure) and temperature. 55370 Lappalainen, T. A u t o m a t e d image analysis method for the detection of c r a c k s on wood s u r f a c e (in Finnish) Valtion Teknillinen Tutkimuskeskus, Espoo (Finland), N9417542/9/GAR, 97 pp. (Jan. 1992) An automated image analysis method was developed for the inspection of cracks on wood surfaces and on paint films. The system is capable of both detecting and analyzing the cracks. The automatic method is capable of classifying the average size of the cracks and the quantity of cracking on the scale 0 to 5 (ISO (International Standards Organization) 4628 standard) with an accuracy of 4-/- I compared to visual classification. The inspection algorithms are based on morphological preprocessing and statistical crack recognition. For optimal thresholding, an experimental system was developed. The image acquisition part of the system is based on a monochrome CCD (Charge Coupled Device) matrix camera. 54787 Furukawa, J.; Furuya H.; Shingyouji, T. Detection of bulk microdefects underneath the surface of Si wafer using infrared light s c a t t e r i n g tomography Japanese Journal o f Applied Physics, Pt. 1. Vol. 32, No. I IA, pp. 5178- 5179 (Nov. 1993) A new method has been developed to detect bulk micredefects (BMD) underneath the surface of a Si wafer using infrared light scattering tomography. In this method, infrared light enters from the cleaved surface obliquely and is totally reflected at the surface of the wafer, in order to eliminate the effect of scattering at the surface. BMD not only underneath the surface of the polished silicon wafer, but also underneath the wafer surface on which devices are fabricated, are easily detected by this method. 54241 Ahmadshahi, M.A.; Krishnaswamy, S.; Nemat-Nasser, S. Dynamic holographic-electrunic speckle-pattern interferometry Journal o f Applied Mechanics, Vol. 60, No. 4, pp. 866-874 (Dec. 1993) development of a nondestructive, full-field, quantitative optical technique, and its feasibility to study dynamic deformations of opaque and diffusively reflecting solids under transient loads, are discussed. The technique involves recording a sequence of dynamically changing two-heam
N DT Abstracts
speckle interference patterns (also called holographic speckle patterns) of a rapidly deforming body which is doubly illuminated by a laser light source. The time sequence of speckle icatterns is recorded by means of a high-speed camera on an ultra-sensitive 3~:-mm film. The developed negatives are then digitized by a CCd camera into an image processing system.
52024 Steckenrider, J.C.; Wagner, J.W. C o m p u t e d speckle decorrelation (CSD) a n d its application for fatigue d a m a g e monitoring Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 28 Jul.-2 Aug. 1991. Vol. I IA, pp. 487-494. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1992) Non-contact surface deformation analysis and mapping can be conducted using a video-based laser speckle technique, at speeds approaching video frame rates. The technique, known as Computed Speckle Decorrelation (CSD), uses the speckle decorrelation associated with surface deformation. CSD means that faster and more quantitative analysis of the progression of fatigue damage in thick graphite/epoxy composite materials is now possible, than was previously available using film-based techniques. CSD combines speckle decorrelation work with real time computer techniques. This study used CSD to monitor fatigue degradation in 2024-T4 aluminium, subjected to reverse bending fatigue.
54054 Fanton, J.T.; Opsal, J.; Willenborg, D.L.; Kelso, S.M.; Rosencwaig, A. Beam profile refiectometry: a new technique for thin film measurement Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 19-24 Jul. 1992. Vol. 12A, pp. 387-394. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1993). ISBN 0-306-44483-6. The information present in the intensity profile of a highly focussed, linearly polarized beam makes the BPR a powerful film measurement technique. The shape and amplitude information in the $ and P profiles of angular reflectivity enable us to determine not only the thickness of a simple film, but also the refractive index, extinction coefficient or even the thicknesses of other films in a multi-layer stack. These measurements all occur in a submicron area making possible measurements on product wafers.
50521 Radha, T.S.; Ramprasad, B.S. M e a s u r e m e n t of the t h e r m a l stress in specularly reflecting thin films using real-time holographic i n t e r f e r o m e t r y Nondestructive Testing and Evaluation, Vol. 8-9, Pt. 2, (1992) Proceedings of the 5th International Symposium on Nondestructive Characterization of Materials, Karuizawa (Japan), 27-30 May 1991. pp. 949-957. Edited by T. Kishi, T. Saito, C, Ruud, and R. Green. In this paper a method of measurement of thermal stress of thin films using real-time holographic interferometry is described, with particular emphasis on specularly reflecting thin films. A few thin film-substrate systems have been used for the measurements. For the copper film on brass substrate and silver on glass theoretical and experimental results are found to agree reasonably well at different temperatures. For the cases of aluminium film and magnesium fluoride film on glass there is a wide discrepancy. However it is pointed out that experimental values are closer to reality.
53807 Ehrlich, M.I.; Stec~[enrider, J.S.; Wagner, J.W. High speed holographic " c i n e m a t o g r a p h y " with f r a m e rates a p p r o a c h i n g 25 nanosecon~ds lntefferometry Applications. Proceedings of Meeting at San Diego, California (United States), 22-23 Jul. 1992. pp. 270-276. Edited by R.J. Pryutriewicz, G.M. Bacon and W.P.C Juptner. SPIE. Vol. 1756 (1993) ISBN 0-8194-0929-4 A holographic recording system has been developed in which a single pulse from a frequency doubled Nd:YAG laser is repeatedly spit and delayed to provide up ~ 10 pulses which are separated both in time and in space. A custom graded beam splitter is used to help insure near equal amplitude of all ten pulses. A White cell provides adjustable delay between the sequential outputs of tbe system over a range from 28 to 170 nanoseconds. By appropriate design of the holographic recording geometry, up to ten distinct holographic frames may be recorded in sequence on a single 4" x 5" film plate. Using the system, studies have been performed on the dynamics of detonation of 100 micron explosive particles and on the acceleration and growth of cracks in brittle materials. CW reconstruction of each holographic frame permits microscopic examination of the reconstructed images so that precise measurements of shock front or crack length may be made as a function of time.
50270 Yamaguchi, I.; Takemori, T.; Kobayashi, K. Biaxiai laser speckle strain gauge (In Japanese: English Abstract) Journal of JSNDI, Vol. 39, No. 8, pp. 682-686 (Aug. 1990) The laser speckle stain gauge, which measures surface strain in a noncontacting and automatic way by optoelectronically detecting and comparing speckle displacements at two symmetrical scattering angles, has been extended to a biaxial configuration, lnplane strains along the orthogonal directions have been measured by using four linear image sensors and high speed correlators with the sensitivity of a few tens of microstrains and a time response of a hundred Hz. The instrument has also been applied to simple and quick determination of Poisson's ratio of polymer films at various loading frequencies.
53804 Dovgalenko, G.Y.; Kadura, S.A. Application of hiologicall p h o t o p o l y m e r to nondestructive testing Interferometry Applications Proceedings of Meeting at San Diego, California (United States), 22-23 Jul. 1992. pp. 227-232. Edited by R.J. Pryutriewicz, G.M. Bacon and W.P.C Juptner. SPIE. Vol. 1756 (1993) 1SBN 0-8194-0929-4. The present paper com;iders the results of investigation of photopolymeric films "Biochea~n" as a reversible media to dynamical holographic interferometry. The optimized condition to writing-readout of hologram were obtained. The n=,sultsof nondestructive testing of materials based on adaptive bolographic interferometer using "Biochrom" are presented.
50268 Musilova,J.; Ohlidal, I. Influence of defects of thin films on d e t e r m i n i n g t h e i r thickness by the method based on white light interference Journal of Physics D. Applied Physics, Vol. 25, No. 7, pp. i 131-1138 (14 Jul. 1992) The usefulness of the thin film thickness determination method based on the principle of white light interference could he limited not only by parameters characterizing the optical system itself (optical constants of the measured and reference systems, the measured thickness of the thin film of interest) but also by other additional effects such as inhomogeneity of optical constants of the measured film, roughness of the boundaries and the existence of surface or interface layers. These effects are discussed.
52779 Radha, T.S; Rampr,~sad, B.S M e a s u r e m e n t of the t h e r m a l stress in specularly reflecting thin films using real-time holographic i n t e r f e r o m e t r y Nondestructive Characteri;,ation of Materials V, Karuizawa (Japan), 27- 30 May 1991. pp 949-957. Edited by T. Kishi, T. Saito, C. Ruud and R. Green. Iketani Science and Technology Foundation (1993) A method of measurement of thermal stress of thin films using real-time holographic intefferometry is described, with particular emphasis on specolarly reflecting thin films. A few thin film-substrate systems have been used for the measurements. For the copper film on brass substrate and silver on glass theoretical and experimental results are found to agree reasonably well at different temperatures. For the cases of aluminium film and magnesium fluoride film on gla,gsthere is a wide discrepancy. However it is pointed out that experimental values are closer to reality.
Bonniau, P.; Chazelas, J.; Lecuellet, J.; Gendre, F.; Turpin, M.; Le Pesant, J.-P.; Brevignon, M. 50002
Damage
detection
in
woven-composite
materials
using
embedded fiber optic sensors Fiber Optic Smart Structures and Skins IV, Massachusetts, Boston (United States), 5-6 Sep. 1991. pp. 52-63. Vol. 1588. SPIE (1991) This paper presents our preliminary results on the use of fiber optic sensors for impact detection on Kevlar-opoxy panels. Interfero- polarimetric measurements have been performed by using two different kinds of polarisation-maintaining optical fibers. The sensitivity of the fibers to internal process stresses and to external impact stresses is discussed with respect to the coating nature. The effect of an over-coating on the fiber sensitivity is also reported, impact-induced delaminations have been observed and the optical response has been adjusted by using an appropriate over-coating.
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