The EZRT is a joint department of the Fraunhofer-Institutes IIS ...and Industry Dr. O. Wiesheu...
Transcript of The EZRT is a joint department of the Fraunhofer-Institutes IIS ...and Industry Dr. O. Wiesheu...
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The EZRT is a joint department of the Fraunhofer-Institutes IIS Erlangen and IZFP Saarbrücken/Dresden
Dr. Randolf Hanke, Dr. Theobald Fuchs
International Workshop on Imaging NDE April 25 – 28, 2007, Kalpakkam, India
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Fraunhofer EZRT – facts & figures
Principles of Computed Tomography
Computed Tomography for the industry
Tasks and applications today
Challenges for the future
Content
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MagdeburgDortmund
SchmallenbergAachen
Euskirchen
Darmstadt
JenaChemnitz
Dresden
Itzehoe
Bremen
Hannover
Braunschweig
Kaiserslautern
Freiburg
Würzburg
Holzkirchen
KarlsruheSaarbrücken
Duisburg
Erlangen/Fürth
Pfinztal
St. Ingbert
MünchenFreising
Oberhausen
Stuttgart
GolmBerlin
St. Augustin
Rostock
EZRT - Locations
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Today:Today:Today:Today:
Locations: Saarbrücken, Erlangen, Fürth, Dresden
Employees: 44 (plus more than 40 part time
scientists and students)
Space: > 2200 m2 labs and offices
Turnover: approx. € 4.6 Mio per annum
Financing: > 80% Projects (industry and public)
< 20% basic funding
Equipment: Currently 14 X-ray machines
Cooperation: Industry, FhG, BAM, PTB, University
EZRT - Facts & Figures
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“Technicum New Materials”
The Bavarian Secretary of State for Trade and Industry Dr. O. Wiesheu
inaugurates the EZRT on July 4th 2000
EZRT - Location Fürth
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Set-up of a CT system and scheme of measurement
Principles of Computed Tomography
Source
Cone Beam
Object
Flat Panel Detector
x
y
z
Axis of Rotation
Image Image Image Image reconstruction reconstruction reconstruction reconstruction clusterclusterclustercluster
High speed High speed High speed High speed networknetworknetworknetwork
Data acquisitionData acquisitionData acquisitionData acquisition
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Volume CT of Large Objects
Tube: Tube: Tube: Tube: 450 kV, 2 kW450 kV, 2 kW450 kV, 2 kW450 kV, 2 kW
Digital Flat Panel Digital Flat Panel Digital Flat Panel Digital Flat Panel with 2048 x 2048 Pixelwith 2048 x 2048 Pixelwith 2048 x 2048 Pixelwith 2048 x 2048 Pixel
(40 cm x 40 cm)(40 cm x 40 cm)(40 cm x 40 cm)(40 cm x 40 cm)
Principles of Computed Tomography
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X-Ray SystemsComputed TomographyComputed TomographyComputed TomographyComputed Tomography
Object geometry
AxialAxialAxialAxial
2D2D2D2D----LayersLayersLayersLayers
3D3D3D3D----VolumeVolumeVolumeVolume
PlanarPlanarPlanarPlanar
LaminographyLaminographyLaminographyLaminography
Digital Digital Digital Digital TomosynthesisTomosynthesisTomosynthesisTomosynthesis
RadiographyRadiographyRadiographyRadiography
FilmFilmFilmFilm DigitalDigitalDigitalDigital
Image ProcessingImage ProcessingImage ProcessingImage Processing
Status of Computed Tomography
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Fast and efficient approximation
Algebraic Reconstruction
Exact analytical Methods (Inversion of the Radon transform)
Filtered backprojection (Feldkamp-type algorithm)
Iterative solution of a multi-dimensional under-determined system of equations
3D Fourier-type method (problems with interpolation in frequency-space)
Laminography Approximate method for slice imaging by defocussingcontributions from the object outside the plane of interest
Status of Computed Tomography
Reconstruction Methods
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Computed Tomography - Laminography
Analogues MethodAnalogues MethodAnalogues MethodAnalogues Method
Focal layer is reconstructedLayers outside the focal plane are blurredAdapted for plane, laminar objects like e.g. Printed Circuit Boards
Rotating SourceRotating SourceRotating SourceRotating Source
Counter rotating DetectorCounter rotating DetectorCounter rotating DetectorCounter rotating Detector
Object in focal planeObject in focal planeObject in focal planeObject in focal planeObjects outside focal planeObjects outside focal planeObjects outside focal planeObjects outside focal plane
System Set UpSystem Set UpSystem Set UpSystem Set Up
Planar CT
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Inspection of electronic Inspection of electronic Inspection of electronic Inspection of electronic multilayer PCBsmultilayer PCBsmultilayer PCBsmultilayer PCBs8 8 8 8 µµµµm bonding wiresm bonding wiresm bonding wiresm bonding wires
3D - Visualization
Oblique radioscopic view
Different layers byTomosynthesis Method
Computed Tomography - Laminography
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• Simple backprojection of projection data P into object space leads to smearing of details
• Compensation: convolution with a Point Spread Function (PSF) proportional to ρρρρ
(Lakshminarayanan & Ramachandran 1971)
• Filtering of projection data Pf
• Backprojection of Pf into the volume
Principles of Computed Tomography
Filtered Backprojection
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Spatial domain Frequency domain
Principles of Computed Tomography
Filtered Backprojection
( ) ( ) ( )[ ]∫ ∫
+∧
=π
θθπωθ θωωω
,0
sincos2,R
yxi ddefRyxf
( ) ( ) ( )∫⊥
+==θ
θ θθ dttsfsRfsfR ,f
( )σθf̂f̂
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Bio Imaging Research
Comet, Feinfocus
GE-IT (FhG)
Hitachi
Phoenix
Procon (FhG)
Scanco
SkyScan
Wälischmiller
Viscom
VJ-Technologies
X-Tec
Yxlon
Industry Microna (FhG)Shake (FhG)
Werth (FhG)
Zeiss (hwm, FhG)
Typical Performance:Typical Performance:Typical Performance:Typical Performance:
Resolution down to 1 µm
Reconstruction of 20483
volumes
Reconstruction time 3,7 s per 10242 slice (Pentium 3 GHz)
Scan times varying with resolution and object
CTCTCTCT----System System System System RayScanRayScanRayScanRayScan 200 (Hans 200 (Hans 200 (Hans 200 (Hans WWWWäääälischmillerlischmillerlischmillerlischmiller GmbH)GmbH)GmbH)GmbH)
CTCTCTCT----System CTSystem CTSystem CTSystem CT----MINI, MINI, MINI, MINI, ProconProconProconProcon
Status of Computed Tomography
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Argonne National Lab, Chicago / USA
Bundesanstalt für Materialforschung und –prüfung(BAM, Berlin / Germany)
EMPA, Switzerland
Fraunhofer-Gesellschaft EZRT (Saarbrücken, Fürth)
General Electric Global Research
Lawrence Berkeley National Laboratory, USA
Leti, Grenoble / France
Siemens, Medical Solutions (Germany)
Synchrotron-facilities: Bessy, Anka, DESY, ESRF (G/F)
University Linköping / Sweden
University Saarland, Germany
Research
Status of Computed Tomography
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system know-how
manipulation
X-ray generation
computer-architecture
X-ray detectors
software
• algorithms
• distributed systems
system design
Automation for industrial Radioscopy and Tomography
EZRT fields of expertise
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Micro CT for high resolution Volume Tomography on micro systems
Example: plastic micro gear
Macro CT for fast Volume Tomography on lightweight components
Examples: Al wheels, motor blocks, metal foams
EZRT product development and business fields
µµµµ----CTCTCTCT
MakroMakroMakroMakro----CTCTCTCT
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Bench Top System CT-MINI for fast and high resolution Volume Tomography
EZRT product development and business fields
CT CT CT CT forforforfor thethethethe laboratorylaboratorylaboratorylaboratory
CT for industrial 3DCT for industrial 3DCT for industrial 3DCT for industrial 3D----metrologymetrologymetrologymetrology
Biological sample
nominal / actual geometry comparison
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– Sub-µ radioscopy and CT
– New applications of automated 2D / 3D Image
processing
– 3D / CAD data fusion
– Industrial process integrated CT: “inline CT”
– High speed radioscopy, dynamic radioscopy
in µs range
– Development centre for non-destructive testing of
new materials in aerospace, funded project by
Bavarian government, 4 years, start April 2005
EZRT research areas today
CT CT CT CT sectionsectionsectionsection of a CFC probeof a CFC probeof a CFC probeof a CFC probe
Structural Structural Structural Structural damage after damage after damage after damage after impactimpactimpactimpact
3D-defect recognition with 100 projections (25 s)
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Physical effects that cause a degradation of image quality
• Beam-hardening with polychromatic radiation
• Scattered radiation
• scatter processes within the object
• primary radiation scattered within the detector
• Properties of the detection system
• Image Lag
• Degradation
• Pixel defects
• Non-Linearities
Artifacts - Methods for Projection Image Correction
EZRT research areas today
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Artefacts and Means for Reduction
• Combination of pre- and post-processing steps
• IAR: Iterative, reference-less and multistagecorrection method (right)
• Ring Artefact Suppression (below)
Status of Computed Tomography
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Artefakt Reduction by Simulation of Scattered Radiation
Projection of a step wedge (Al)
Scattered radiation of the step wedge
Scattered radiation of an Al-block
EZRT research areas today
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• No quantitative information on defects possible by transmission radioscopy
• 3D CT can provide complex spatial information about a component and contained unwanted elements therein
• Evaluation based on 3D methods is less prone to artifacts than 2D methods
• Fast computers and algorithms allow for pace keeping reconstruction and analysis
• Relatively low resolutions necessary for NDT tasks
Fast Inline 3D Computed TomographyMotivationMotivationMotivationMotivation
Status of Computed Tomography
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3D-CT and defect recognition, 100 s
Fast Inline 3D Computed Tomography: Fast Inline 3D Computed Tomography: Fast Inline 3D Computed Tomography: Fast Inline 3D Computed Tomography: Results of a fast scanning combined with image processingResults of a fast scanning combined with image processingResults of a fast scanning combined with image processingResults of a fast scanning combined with image processing
3D-CT and defect recognition, 25 s
Status of Computed Tomography
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Inspection Tasks in the Field of Aerospace
• Highly absorbing materials
• Composites with low contrast
• Very large objects
• High resolutionStabilizer of a Rotor Blade
Turbine Blade
Status of Computed Tomography
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Challenge Turbine Blades
Combination of highly Combination of highly Combination of highly Combination of highly absorbing material with absorbing material with absorbing material with absorbing material with complex structurecomplex structurecomplex structurecomplex structure
High resolution CT to visualize small boreholes (< 50 µm)
Status of Computed Tomography
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Composite MaterialComposite MaterialComposite MaterialComposite Material
• Carbon/Glass fiber reinforced plastics
• Complex weaved structures
• Low contrast of embedded materials
Status of Computed Tomography
Challenge Rotor Blades
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Status of Computed Tomography
Inspection tasks in the field material characterization
3D image processing and evaluation of carbon fiber reinforced plastics (CFC)
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Inspection tasks in the field of automotive3D Defect Visualization of Wheel Samples
CT Processed SamplesCT Processed SamplesCT Processed SamplesCT Processed Samples
Center Region
Spoke Region
Rim Region
Status of Computed Tomography
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Inspection tasks in the field of biology
Bug
Lily
Seed of a sugar beet
Trachea of a butterfly cocoon
Status of Computed Tomography
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Micro Gearbox: 2.8 µm Voxelresolution
1,8 mm
Status of Computed Tomography
lubricating grease
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Archaeology
Status of Computed Tomography
Reconstruction of a terracotta head made by the African NokcultureBy courtesy of the laboratory Kotalla
3D surface2D slice
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Paleontology
Status of Computed Tomography
CT reconstruction from about 400 x-ray images of the slab with the hidden Ganoid fishBy courtesy of Dr. Viohl, Eichstätt
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Microsystems → Nanosystems
Offline CT → Inline CT
Qualitative → Quantitative
Stationary → Mobile
Future Trends in Computed Tomography
NanoNanoNanoNano CTCTCTCT to achieve highest-resolution volume data of nano-systems with voxelsize below 100 nm
Inline CTInline CTInline CTInline CT for fast 3D inspection of light metal parts, scan- and evaluation in less than 25 s
Industrial 3DIndustrial 3DIndustrial 3DIndustrial 3D----MetrologyMetrologyMetrologyMetrology with
Computed Tomography
RobotRobotRobotRobot----CTCTCTCT to inspect very large objects on site by mobile CT
WerthWerthWerthWerthTomoScopeTomoScopeTomoScopeTomoScope
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Quantitative CT - QCT
Future Trends in Computed Tomography
CT as an instrument to measure a physical property at an arbitrary point in space
Levels of improvement:
- Exact measurement of primary intensity
- Precise linearization of the projection images
- Reduction of scattered radiation: e.g. by a-priori knowledge on the inspected part
- Mulit-material beam-hardening correction
- Dual-energy-methods: two scans with different high-voltage
Dual Energy CT of a cube made of plexiglas and aluminum
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Challenge Sub-µ CT:The limiting factor is the focal spot size of about 1,3 µm (fwhm)
Measurement with about 2 µm resolution
Biological sample –cocoon of a butterfly
Progress Towards Sub-µm CT
(Dr. N
. Uhlmann, EZRT)
(Dr. N
. Uhlmann, EZRT)
(Dr. N
. Uhlmann, EZRT)
(Dr. N
. Uhlmann, EZRT)
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Carbon fibre reinforced materials
Progress Towards Sub-µm CT1 mm 1 mm 1 mm 1 mm
(St.
(St.
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chl
Schl
Schl
Schl öö öötzer
tzer
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ZRT)
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resolution: 2 µm
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High-resolution CT with grey cast iron
(P. Kr
(P. Kr
(P. Kr
(P. Kr üü üüger, E
ZRT)
ger, E
ZRT)
ger, E
ZRT)
ger, E
ZRT)
Fragment of cast iron with 1 mm size (ca. 2 µm voxel size). The probe contains fiber-like lamella of graphite or cementite
Progress Towards Sub-µm CT
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High-resolution CT of glass fibers with 850 nm voxel size
Progress Towards Sub-µm CT
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Low energy Low energy Low energy Low energy –––– high high high high contrast measurementscontrast measurementscontrast measurementscontrast measurements
Sensor: MediPix 2X-ray tube: MCB-20 (5 – 20 kV)
Usability: Polystyrene, plastics, organic materials
MediPix 2
Low-energyX-ray tube (focal spot: 3 mm)
He-tunnelRotary disk
The experiments were conducted in collaboration with the Physical Institute IV (University of Erlangen-Nuremberg), Prof. Dr. Gisela Anton
Integration of New X-Ray Sensor Technologies
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Integration of New X-Ray Sensor Technologies
Direct converting detectorDirect converting detectorDirect converting detectorDirect converting detector
Technical data:
• Sensor material: CdTe• Pixel size: 100 µm x 100 µm• Number of pixels: 252 x 1014• Area: 25.2 x 101.4 mm2
• DQE: > 90% at 60 keV• Energy range: 15 – 300 kV• Frame rate: up to 50 fps
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Slice of a fiber composite floor cover
Carbon fiber mat at 35 kV
Integration of New X-Ray Sensor Technologies
Low Energy CT
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ESD foam:
8 kV / 6 mAs
Cigarette:
12 kV / 7 mAs
Sticky tape step wedge:
8 kV / 40 mAs
Integration of New X-Ray Sensor Technologies
Low Energy CT
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Metrology: Extracting Surface Data
Nominal / A
ctual Value
Comparison
STL Data Surface Visualization
Metrology with Computed Tomography
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Robot Aided Computed Tomography
Very large objects (e.g. aircraft wings or fins) can be inspected on site by mobile CT
One robot carries the X-ray source, a second one the detector
→ precise positioning and robot communication necessary
Source: Fraunhofer IPA, StuttgartX-ray source
detector
Mobile Computed Tomography
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Outstanding capabilities of CT in NDT today
1. Material testing
2. Dimensional Measurement
3. Control of integrity and completeness
Fields of progress in the near future
1. Detector systems with higher dynamic, greater area and better efficiency
2. X-ray sources providing higher intensities with small focal spots
3. Algorithms for ROI-reconstructions from a limited number of projections
4. Efficient means to reduce artifacts from beam hardening and scattered radiation
The Future in 3D Industrial Computed Tomography
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AcknowledgmentAcknowledgmentAcknowledgmentAcknowledgment
Parts of this work was coParts of this work was coParts of this work was coParts of this work was co----financed by the European financed by the European financed by the European financed by the European Union and the Free State Union and the Free State Union and the Free State Union and the Free State of Bavaria of Bavaria of Bavaria of Bavaria
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Thanks to all people who kindly contributed: Dr. Ulf Haßler, Dr. Michael Maisl, Dr. Thomas Wenzel, Dr. Stefan Kasperl, Steven Oeckl, Ingo Bauscher, Stefan Schlötzer, Stefan Schröpfer, Peter Krüger and Ms. Wutz
Fraunhofer EZRT @ INDE 2007