Dynamic speckle analysis with coarse quantization of the raw data

Analysis of dynamic speckle formed on the surface of diffusely reflecting objects under laser illumination is a non-contact method for inspection of speed of processes. The paper deals with intensity-based implementation of the method that relies on statistical processing of correlated in time seque...

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Bibliographic Details
Published in:Applied optics (2004) 2020-03, Vol.59 (9), p.2810
Main Authors: Stoykova, Elena, Nazarova, Dimana, Nedelchev, Lian, Ivanov, Branimir, Blagoeva, Blaga, Oh, Kwan-Jung, Park, Joongki
Format: Article
Language:English
Subjects:
Data analysis
Data compression
Inspection
Measurement
Probability density functions
Speckle patterns
Statistical analysis
Time compression
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Summary:Analysis of dynamic speckle formed on the surface of diffusely reflecting objects under laser illumination is a non-contact method for inspection of speed of processes. The paper deals with intensity-based implementation of the method that relies on statistical processing of correlated in time sequences of speckle images. A two-dimensional activity map is built for each sequence to visualize regions of different speed on the object surface at a given instant. A great number of images is required to track a process in time. We propose data compression by coarse quantization of the raw speckle data. Efficacy of quantization is analyzed by simulation and experiment for low- and high-contrast speckle patterns with bell-shaped and long-tailed distributions of intensity, respectively. Non-uniform quantization is proposed for long-tailed speckle intensity distributions. Decreasing the bit depth from 8 to 4 causes no change in the probability density function of the activity estimate.
ISSN:1559-128X
2155-3165
DOI:10.1364/AO.384204