Please explain the cause of the laser speckle pattern

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SUMMARY

The discussion centers on the phenomenon of laser speckle patterns observed when using a laser pointer in conjunction with a concave mirror. The user successfully expanded a 5mm laser beam to a 30cm area, noting that the irregular speckle pattern remained stationary despite moving the beam. The user hypothesizes that this pattern is caused by either irregularities in the mirror or impurities in the laser's lens, confirming the presence of a speckle pattern as defined in laser optics.

PREREQUISITES
  • Understanding of laser optics and beam propagation
  • Familiarity with concave mirrors and their reflective properties
  • Knowledge of speckle patterns in coherent light sources
  • Basic principles of light interference and diffraction
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  • Research the physics of laser speckle patterns in detail
  • Explore the effects of surface irregularities on laser reflection
  • Investigate methods to minimize impurities in laser optics
  • Learn about applications of laser speckle in imaging and measurement techniques
USEFUL FOR

Students and professionals in optics, physicists studying laser behavior, and hobbyists experimenting with laser technologies will benefit from this discussion.

SF
I was playing with a laser pointer and a concave mirror and I managed to get a 5mm beam to spread over a 30cm area.
http://img361.imageshack.us/img361/1884/mspaintfg0.png
http://img228.imageshack.us/img228/1866/lpuc9.jpg
http://img228.imageshack.us/img228/3581/lp0ii9.jpg

The irregular pattern remained stationary even when I moved the beam, so I guess it's due to (a) irregularities in the mirror or (b) impurities in the laser's lens?
 
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I expect you are talking about a speckle pattern... Look up laser speckle in Wikipedia...
 

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