PERSISTENT SURVEILLANCE FOR PIPELINE PROTECTION AND THREAT INTERDICTION Haibo Huang Rich Stephens...
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Transcript of PERSISTENT SURVEILLANCE FOR PIPELINE PROTECTION AND THREAT INTERDICTION Haibo Huang Rich Stephens...
PERSISTENT SURVEILLANCE FORPIPELINE PROTECTION AND THREAT INTERDICTION
Haibo HuangRich Stephens
Brian VermillionDan Goodin
Bernie Kozioziemski (LLNL)
HAPL Meeting, Livermore, California
June 20-21, 2005
Radiographic Dimension Measurement of Dry DVB Foam
Shells
IFT/P2005-072
Summary
• IFE program uses 4.1 mm O.D. foam shells• Require dimension variations measured to
<1 m• Optical characterization requires immersion
in index-matching fluid.• X-Radiograph system already developed &
tested– Contact images on high resolution film– High precision film digitizer – Analysis algorithm to handle extreme noise
• For the first time, large dry DVB foam shells can be measured
IFE Point Design for DVB Foam Shells
• Sufficient to measure interface radii vs angle to ±1 m
4100 ±200 m
Average Foam Wall: 289 ±20 m Non-concentricity (NC): < 1% *
* NC= (OD/ID Center Offset)/WallAverage
equivalent to WallMax-WallMin < 6 m
** OOR=(ODmax-ODmin)/RadiusAverage
equivalent to Rmax-Rmin = 10 m
CH Wall: (1-5) ±1 m Out-Of-Round (OOR): < 1% **
Foam is difficult to characterize
• Visible light measurements require index matching fluid– Time-consuming– Potential dimension errors
• OD changes by 1-5%• Thicker CH, larger OD change
• X-radiographs are noisy due to large density fluctuations– Obscures interfaces
Radius (um)
Tra
nsm
iss
ion
(a.
u.)
Area AverageSingle line
100 m
wallinterior
X-radiography works when digitized properly
• 12bit, 4 MB, Cooled CCD– Measure whole shell to 0.8
m• Plan APO Microscope lens
– Flat field => CCD compatible– Large N.A. => high resolution
• Type K1a film– Finest grain – Glass substrate => stable
• Software– Noise reduction and rejection– Edge analysis
Accurate interface profiling require lens correction
-3
-2
-1
0
1
2
3
-800 -400 0 400 800Radius from Image Center (um )
Dis
tort
ion
(u
m)
• Must correct lens distortion– Calibrate with stage
micrometer– Verify with circular
standards
• Each lens calibrated separatelyDoes radius and shape
change with position?
3µm pixel error
Foam structure causes unique analysis problems
• Traditional vision-based analysis does not work with low contrast, noisy image– Reduce noise by azimuthal averaging– Reject noise by data correlation– Limit search range
• Interface very wavy with thin overcoat– Flattening (Step 3)
• Extended interface structure– Fresnel simulation determines offset
Capturing edge information
An
gle
Radius
1) Inspect thickness variation by 360˚ unwrapping
2) Sharpen interface with 2nd derivativeD. Bernat, R.B. Stephens, Fusion Technology, V31, P473, 1997
An
gle
Radius
Mapping interface requires careful consideration
3) Sharp outside edge good for auto alignment
4) Reject noise by correlating peak/valley locationsReduces the image to a set of R() files
Separates wavy interfaces => narrows search range
An
gle
Radius
An
gle
Radius
visualize wall thickness variation
Calculating interfaces and walls
Interface Marker (4X)
1200
1300
1400
1500
1600
0 100 200 300
Angle (degree)
Ra
diu
s (
um
)
OD: 3200 ± 3 m
OOR: 0.88 ± 0.04 % DVB Foam Wall (4X)
332
342
352
0 100 200 300Angle (degree)
Wa
ll T
hk
n
(um
)
Non-Concentricity: 2.7 +/- 0.2 %
5) Unflatten and record data4X lens radius measurement repeatability: <0.4 m
CH Wall (4X)
8
10
12
14
0 100 200 300
Angle (degree)
Wal
l Thk
n (u
m)
Wall Variation: 1.1 +/- 0.4 um
Correcting Walls
6) Apply offset correction (under development) •Measured profile has width
•Relation fixed between profile and interface•Specific to shell type and lens•Described by markers (peak/valley) and offsets
•Offset understood by modeling•Affected by phase contrast, pixel size, X-ray spectrum etc.
Fresnel calculation of 15umGDP/20umBe @ 10X
0
0.5
1
975 980 985 990 995 1000 1005 1010 1015 1020 1025 1030
Radius (um)
Am
plitu
de
-0.4
-0.2
0
0.2
0.4
Transmission
2nd Derivative
Be/GDP interfaceGDP surface Be surface
Porosity may affect interface sharpness
• Phase contrast shows as white ring at the sharp interfaces of dissimilar materials– Strong at CH/RF foam, CH/Be interfaces – but not for CH/DVB –Diffused due to pore size?
CH on DVB foamCH on RF Foam
~0.1 m pore ~1 m pore
50 m
50 m
Estimated X-Radiography Capabilities
Lens
Image resolution (m)
Maxim OD(mm)
MinimResolvable Layer (m)
Profile Repeat-ability (m)
Wall thkn Accuracy (m) *
Method
2X 3.7 6.0 10 0.8 1 2nd Deriv.
4X 1.9 3.3 6 0.4 0.5 2nd Deriv.
10X 0.8 1.4 2 N/A 1 Transmission
20X 0.4 0.7 1 N/A 0.5 Transmission
* After applying offsets determined by Fresnel calculation
Special concerns for DVB foam shells
• Use low mag. 2nd derivative analysis for foam– May not resolve thin CH overcoat– But get the complete foam radius profile
• Determines foam wall, shell diameter, OOR and NC
• Use high mag. transmission analysis for CH– Noise too high for 2nd derivative method– Measure local CH wall thickness
• Do NOT apply the offsets for Be/GDP shells– Offsets specific to shell type and shell size
Future Possibilities
• Noise analysis could give quantitative opacity variation– IFE specification: <0.3% density variation over
50-100um• No characterization method yet
– Calculate sample opacity from film transmission• Film model already developed for the ICF program
• Orthogonal views allow 3D NC measurement– 90˚ Rotating device
• While sample stays in XRF holder