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Coherence theory of a laser beam passing through a moving diffuser
Gaoming Li1, Yishen Qiu, Hui Li
1Key Laboratory of OptoElectronic Science and Technology for Medicine Ministry of Education, Fujian Normal University, Fuzhou 350007, China.
Optics Express
|June 6, 2013
Summary
We developed a new theory for laser coherence through moving diffusers. Experiments show spatial coherence decreases, but temporal coherence remains unchanged, differing from prior theories.
Area of Science:
- Optics and Photonics
- Laser Physics
Background:
- Understanding laser beam coherence is crucial for applications.
- Previous theories suggested both temporal and spatial coherence decrease when passing through a moving diffuser.
Purpose of the Study:
- To present a general coherence theory for laser beams interacting with a moving diffuser.
- To investigate the impact of diffuser movement on temporal and spatial coherence.
- To develop a method for calculating speckle contrast.
Main Methods:
- Developed a general coherence theory.
- Conducted experiments using a Michelson interferometer.
- Applied eigenvalue theory for speckle contrast calculation.
Main Results:
- Theoretical analysis indicates a decrease in spatial coherence area.
- Experimental results confirm temporal coherence remains unchanged.
- The findings contradict the original coherence theory.
Conclusions:
- The temporal coherence of laser beams is unaffected by diffuser movement.
- Spatial coherence decreases, contrary to previous theoretical predictions.
- A novel method for speckle contrast calculation was established.
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