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Ghost fringe removal techniques using Lissajous data presentation
David J Erskine1, J H Eggert1, P M Celliers1
1Lawrence Livermore National Laboratory, L-487, Livermore, California 94551, USA.
The Review of Scientific Instruments
|April 3, 2016
Summary
Accurately removing ghost artifacts from VISAR (Velocity Interferometer System for Any Reflector) data is crucial for precise shockwave experiments. This study presents a novel method using Lissajous path analysis to correct these artifacts, improving equation of state measurements.
Area of Science:
- * Physics
- * Materials Science
- * Optical Diagnostics
Background:
- * The Velocity Interferometer System for Any Reflector (VISAR) is vital for shockwave experiments, measuring material equations of state (EOS) under extreme conditions.
- * Unwanted laser reflections from target windows create 'ghost artifacts' in VISAR data, distorting or obscuring true velocity signals.
- * Accurate removal of these ghost artifacts is essential for high-precision EOS measurements, particularly with weak shock front reflections.
Purpose of the Study:
- * To develop and validate a robust method for removing ghost artifacts in VISAR data.
- * To improve the accuracy of equation of state measurements in shockwave experiments.
- * To provide a technique applicable to generic interferometers and surface metrology.
Main Methods:
- * Utilizing Lissajous plots of the complex fringe signal to identify and correct the center of the signal path, even with time-varying intensity.
- * Applying a simple translation in the complex plane to recenter the Lissajous path and eliminate ghost contributions.
- * For continuous velocity histories, plotting fringe magnitude versus non-fringing intensity to optimize linearity and determine ghost offsets.
- * For discontinuous velocity histories, employing graphical methods comparing data from two VISARs with different velocity-per-fringe sensitivities.
Main Results:
- * A novel ghost artifact removal technique based on Lissajous path analysis has been developed.
- * The method effectively recenters the VISAR signal path by correcting for ghost contributions.
- * Linearity optimization in fringe magnitude vs. intensity plots proves valuable for continuous velocity data.
- * Graphical comparison of dual-VISAR data successfully determines ghost offsets for discontinuous velocity histories.
Conclusions:
- * The developed Lissajous path analysis method provides an accurate and effective means of removing ghost artifacts from VISAR data.
- * This technique enhances the reliability of equation of state measurements in shockwave science.
- * The method is versatile and can be applied to other interferometric techniques for artifact removal.
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