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Neighbor Pattern Averaging & Reindexing (NPAR)

EDAX NPAR™, or Neighbor Pattern Averaging & Reindexing, is an innovative approach to measuring crystallographic orientation from electron backscatter diffraction (EBSD) patterns. Noise can reduce EBSD indexing performance by hindering the detection of the diffraction bands. Noise is introduced into EBSD patterns by amplifying the signal to obtain faster camera frame rates. EDAX’s advanced indexing and band detection routines perform well even with considerable noise. However, band detection becomes unreliable, and indexing performance suffers when the noise exceeds allowable limits. Noise levels can be lowered by reducing the gain on the detector and averaging multiple frames together. However, both approaches increase the acquisition time necessary for EBSD pattern collection and orientation mapping.

Neighbor Pattern Averaging & Reindexing (NPAR™)

 

With NPAR, the collected EBSD pattern is averaged with all the closest surrounding EBSD patterns on the mapping grid and then indexed. This approach reduces the image noise similar to frame averaging but without the associated time penalty. This improves the SNR of the pattern and allows the EBSD detector to be operated at higher gain settings than conventionally used without sacrificing indexing performance. NPAR can be used to operate the EBSD detector faster at a given beam current, run at lower beam currents and voltages, or improve the quality of data collected under traditional settings.

Features and benefits

Improved indexing performance through increased SNR
  • EBSD patterns averaged with neighboring patterns to reduce temporal noise improving band detection and pattern indexing
  • A time penalty of traditional frame averaging eliminated
Faster collection speeds at any given beam current
  • Operation at higher gains allows for faster frame rates with successful indexing results
Operation at lower acceleration voltages and beam currents
  • Improved spatial resolution
  • Ideal for non-conductive and beam-sensitive samples
Enhanced EBSD image quality mapping
  • Averaging of patterns adjacent to grain boundaries increases pattern overlap, and image quality contrasts relative to grain interiors
Improved orientation precision
  • Increased EBSD pattern SNR improves band detection and resulting orientation precision
  • Improved characterization of deformed materials when step size is less than the scale of the deformation substructure
Compatible with APEX™ EBSD and OIM Analysis™ software
  • OIM Analysis Data Collection users can import patterns into OIM Analysis for NPAR indexing

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