Noise analysis in outdoor dynamic speckle measurement

Area of Science:

• Optical Metrology
• Non-Destructive Testing
• Image Processing

Background:

• Dynamic Speckle Method (DSM) is valuable for process speed estimation.
• Industrial inspection often requires outdoor measurements with inherent noise.
• Environmental factors like vibration and ambient light can degrade DSM performance.

Purpose of the Study:

• To analyze the efficiency of DSM under environmental noise conditions.
• To investigate normalized estimates for non-uniform laser illumination.
• To prove the feasibility of outdoor DSM measurements.

Main Methods:

• Statistical pointwise processing of time-correlated speckle patterns.
• Numerical simulations of noisy image capture.
• Real-world experiments with test objects under outdoor conditions.

Main Results:

• DSM performance was evaluated in the presence of phase fluctuations and shot noise.
• Normalized estimates were studied for non-uniform illumination scenarios.
• Simulations and experiments confirmed good agreement between ground truth and noisy data maps.

Conclusions:

• The dynamic speckle method is robust to environmental noise for outdoor applications.
• Feasibility of outdoor DSM for industrial inspection is demonstrated.
• Accurate speed distribution mapping is achievable even with noisy data.