Image Enhancement of Polycrystalline Aluminum Electron Diffraction Patterns ECE 533 Fall Semester 2003 Final Project Paul Larsen William Stratton

Outline Background: Electron diffraction patterns Experimental procedure Results Conclusions

Background: Electron Diffraction Patterns Tremendous amount of data present –Atomic Structure –Composition –Material Constants Simplified ray diagram of a typical TEM. The specimen would be placed above lens 1. Diffraction patterns of specimens are viewed at the back focal plane. Diffraction patterns of an A1 single crystal, polycrystalline gold, and amorphous carbon respectively. Williams, D., Carter, CB, Transmission electron microscopy, Plenum Press, NY, 1996

Experimental Procedure Shift Level msxxxx 100msxxxx 500msxxx 1000msxxxx 5000msxxx 10000msxx 20000msxx 30000msx Exposure Time Step 1. Obtain diffraction pattern images of polycrystalline Aluminum for several Shift Level/Exposure Time combinations:

Step 2: Apply image enhancement techniques to all images: –Log transformation: –Power-law transform: –Histogram equalization: –Median filter Experimental Procedure Step 3: Visually inspect to determine which transformations extract the most data from the patterns while also minimizing the noise

Results: The Best Transformations for Each Shift Level/Exposure Time Combo. Shift Level ms Log or Power-law with γ = 0.3 Power-law with γ = 0.4 Power-law with γ = 0.5 Power-law with γ = ms Log or Power-law with γ = 0.3 Power-law with γ = 0.4 Power-law with γ = 0.45 Power-law with γ = ms Log or Power-law with γ = 0.3 Power-law with γ = 0.45 Power-law with γ = ms Log or Power-law with γ = 0.3 Power-law with γ = 0.4 Power-law with γ = ms Log or Power-law with γ = 0.3 Power-law with γ = 0.35 Power-law with γ = ms Power-law with γ = 0.35 Power-law with γ = ms Power-law with γ = 0.35 Power-law with γ = ms Power-law with γ = 0.35 Exposure Time

Sample Results

Conclusions Image Enhancement very beneficial for electron diffraction images Best results obtained using power law and log transformations combined with median filter For power-law transform, increase γ as shift level increases or as exposure time decreases