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Interference fringes with maximal contrast at finite coherence time
1Department of Physics and Mathematical Physics, Adelaide University, Adelaide SA5005, Australia.
Physical Review Letters
|October 26, 2002
Summary
Interference fringes in wave field measurements peak in contrast with finite coherence times. An acoustic experiment shows maximal fringe contrast occurs with partial coherence, not full coherence.
Area of Science:
- * Physics, Optics, Acoustics, Signal Processing
Background:
- * Fourth-order correlation functions in wave fields can produce interference fringes.
- * These statistical fringes exhibit maximum contrast for finite coherence times.
- * Interpreting interference patterns requires careful consideration of field coherence properties.
Purpose of the Study:
- * To investigate the relationship between field coherence and interference fringe contrast.
- * To demonstrate maximal fringe contrast under conditions of partial coherence.
- * To highlight challenges in interpreting interference when the Gaussian moment theorem is inapplicable.
Main Methods:
- * Measurement of four-time fourth-order correlation functions of a wave field.
- * Utilizing a simple acoustic experiment to observe interference fringes.
- * Employing random telegraph phase noise to systematically vary field coherence.
Main Results:
- * Interference fringes were observed, confirming their statistical origin.
- * Maximal fringe contrast was experimentally demonstrated to occur at partial coherence.
- * Random telegraph phase noise illustrated the limitations of the Gaussian moment theorem in this context.
Conclusions:
- * The contrast of interference fringes is strongly dependent on the coherence time of the wave field.
- * Partial coherence, rather than full coherence, yields the greatest fringe contrast.
- * Careful theoretical approaches are needed for interference analysis with non-Gaussian noise sources.
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