Radiography and Image Processing

Transcription

1 Radiography and Image Processing: February 8, 0 OE/NV/ Radiography and Image Processing Stephen E. Mitchell, Principal Scientist National Security Technologies, LLC mitchese@nv.doe.gov This work was done by National Security Technologies, LLC, under Contract No. E-AC5-06NA5946 with the U.S. epartment of Energy and supported by the Site-irected Research and evelopment Program.

2 Radiography and Image Processing: February 8, 0 Outline Introduction What? Why? Etc. Pulsed Power iode Physics Radiography ABC s Challenges

3 Radiography and Image Processing: February 8, 0 Introduction Subcritical Experiment (SCE) program initiated after 99 moratorium on underground nuclear testing in support of stockpile stewardship High energy radiography was developed over the years to complement existing surface diagnostics (i.e. Photon oppler Velocimetry [PV], velocity interferometer system for any reflector [VISAR ]) Material science: Provides spatial view, internal density measurement

4 Radiography and Image Processing: February 8, 0 Pulsed Power Marx Blumlein PFL

5 Radiography and Image Processing: February 8, 0 iode Physics Pulsed Power Hi-Z, TTB, electron photon converter (e.g. Tungsten or Tantalum) Bremsstrahlung photon flux, Φ(E), goes as (7.5E-4) (Z) (KE electron ) in a TTB target iode current may be space charge limited (SCL) in hi impedance configuration Leff 3 I SCL V r c r f (ln ) a r a iode current may be magnetically limited (ML) in lo impedance configuration where I ML ( γ ) r ln r a G. Cooperstein, et. al., Theoretical Modeling and Experimental Characterization of a Rod-Pinch iode, Physics of Plasma, Vol 8, Num 0, 0/00 c = mc + qv γ

6 Radiography and Image Processing: February 8, 0 Example Radiographic Setup ual Radiographic Configuration Produces Two Time- Separated Radiographs of Equivalent Views - Example

7 Radiography and Image Processing: February 8, 0 iagnostics on Radiographic System iode Assy. iode Assy. Cutaway cartoon Pinhole cameras Pinhole camera radiograph

8 Radiography and Image Processing: February 8, 0 Radiography ABC s Test setup for spot-size measurement Test setup for detector blur measurement

9 Radiography and Image Processing: February 8, 0 Radiography ABC s (Cont.)

10 Radiography and Image Processing: February 8, 0 Radiography ABC s (Cont.) Spot-Size (blur) Measurement Algorithms and Metrics

11 Radiography and Image Processing: February 8, 0 e-blurring ( e-convolution) Observed blurred Image e-convolved with proper PSF e-blurred Image

12 Radiography and Image Processing: February 8, 0 Raw and e-blurred Scatter Test Object 8 mm dia. Ta Shims Thickness (mm)

13 Radiography and Image Processing: February 8, 0 Transfer Response Relation to Areal ensity Radiograph of a graded collimator Logarithmic ratio of Radiograph of a graded collimator to flat-field Scaled (calibrated) to yield - areal density plot

14 Radiography and Image Processing: February 8, 0 µ µ µ = = = ln T e e x x ( )( ) ( )( ) n n x x x x T T T e e e e = Π = = = 0 0 µ µ µ µ Transfer Response & Selective Image e-coupling (Ideal)

15 Radiography and Image Processing: February 8, 0 Scattered Field (real world) S e 0 µ x + S S S 0 ( µ )( ) ( ) ( ) x µ x µ x µ x e e + S e + S e

16 Radiography and Image Processing: February 8, 0 Complications and challenges Bremsstrahlung source spectrum (non mono-energetic source spectrum) Scatter field contribution OF issues; ill-defined light origin within scintillator, fast low F-number imaging system, light collection efficiency Non-symmetric objects beyond Abel transforms toward Radon transforms with > line of sight views Normalization flat field and dark field normalization, shot-shot variations