PERSISTENT SURVEILLANCE FOR PIPELINE PROTECTION AND THREAT INTERDICTION Haibo Huang Rich Stephens Brian Vermillion Dan Goodin Bernie Kozioziemski (LLNL) HAPL Meeting, Livermore, California June 20-21, 2005 Radiographic Dimension Measurement of Dry DVB Foam Shells IFT/P

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)/Wall Average equivalent to Wall Max -Wall Min < 6  m ** OOR=(OD max -OD min )/Radius Average equivalent to R max- R min = 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) Transmission (a.u.) Area Average Single line 100  m wall interior

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 Must correct lens distortion –Calibrate with stage micrometer –Verify with circular standards Each lens calibrated separately Does 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 Angle Radius 1) Inspect thickness variation by 360˚ unwrapping 2) Sharpen interface with 2 nd derivative D. Bernat, R.B. Stephens, Fusion Technology, V31, P473, 1997 Angle Radius

Mapping interface requires careful consideration 3) Sharp outside edge good for auto alignment 4) Reject noise by correlating peak/valley locations Reduces the image to a set of R(  ) files Separates wavy interfaces => narrows search range Angle Radius Angle Radius visualize wall thickness variation

Calculating interfaces and walls 5) Unflatten and record data 4X lens radius measurement repeatability: <0.4  m

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.

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

Estimated X-Radiography Capabilities LensImage resolution (  m) Maxim OD (mm) Minim Resolvable Layer (  m) Profile Repeat- ability (  m) Wall thkn Accuracy (  m) * Method 2X nd Deriv. 4X nd Deriv. 10X N/A1Transmission 20X N/A0.5Transmission * After applying offsets determined by Fresnel calculation

Special concerns for DVB foam shells Use low mag. 2 nd 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 2 nd 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 um 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