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Spatial and temporal coherence of filtered thermal light
Lorenzo Basano1, Pasquale Ottonello, Giovanni Rottigni
1Departimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy. basano@fisica.unige.it
Applied Optics
|December 3, 2003
Summary
Reducing filter bandwidth in double-slit experiments with partially coherent light does not yield perfect interference fringe visibility. Instead, fringe visibility approaches the spectral degree of coherence, revealing more fringes.
Area of Science:
- Optics
- Quantum Optics
- Wave Phenomena
Background:
- The theory of partial coherence describes light wave correlations.
- Interference fringe visibility is a key metric in optical experiments.
- Previous studies suggest limitations on fringe visibility with finite sources.
Purpose of the Study:
- To experimentally verify predictions of partial coherence theory regarding interference fringe visibility.
- To investigate the effect of filter bandwidth reduction on fringe visibility.
- To quantify the relationship between filter bandwidth and spectral degree of coherence.
Main Methods:
- Utilizing a double-slit apparatus illuminated by a primary source of finite extent.
- Employing a tunable optical filter to control the passband.
- Employing a highly sensitive charge-coupled device (CCD) camera for precise fringe detection.
Main Results:
- Interference fringes did not achieve unit visibility even with a narrow filter passband.
- Fringe visibility asymptotically approached the modulus of the spectral degree of coherence.
- A reduction in filter bandwidth led to an increase in the number of visible interference fringes.
Conclusions:
- Experimental results align with theoretical predictions of partial coherence theory.
- Filter bandwidth is a critical factor influencing interference fringe visibility.
- The spectral degree of coherence fundamentally limits fringe visibility in such systems.