Analysis on Combination of Different Wavelengths in Surface Roughness Measurement by Polychromatic Laser Speckle Patterns

2011 ◽  
Vol 189-193 ◽  
pp. 1978-1981
Author(s):  
Jing Huang ◽  
Jian Wei Zhang ◽  
Yan Hua Zhang ◽  
Zong Heng Yuan
Keyword(s):  
Surface Roughness ◽  
Measurement Precision ◽  
Laser Speckle ◽  
Roughness Measurement ◽  
Elongation Ratio ◽  
Measuring Process ◽  
Speckle Field ◽  
Measuring Surface ◽  
Speckle Patterns ◽  
The Difference

Based on the method of polychromatic speckle autocorrelation measuring surface roughness, this paper discussed the influence of the combination of different wavelengths on speckle patterns and speckle elongation ratio when rough surface and polychromatic speckle patterns were simulated. The results show that the smaller the difference of wavelengths combination is, the further peak of the speckle elongation ratio is from the speckle field centre, for the same surface roughness. And the wider area of speckle elongation effects extends. Therefore, influence of combination of wavelengths on measurement precision should be taken into consideration during measuring process.

Measurement of Curved Surface Roughness by Polychromatic Speckle Method

2012 ◽  
Vol 538-541 ◽  
pp. 256-259 ◽  
Author(s):  
Jing Huang ◽  
Zong Heng Yuan ◽  
Yi Fan Ge
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Measurement Precision ◽  
Curved Surface ◽  
Curvature Radius ◽  
Elongation Ratio ◽  
Measuring Process ◽  
Measuring Surface ◽  
Speckle Patterns

The influence of curved surface on the method of polychromatic speckle autocorrelation measuring surface roughness is studied by introducing the curvature radius of surface. The rough surface, and the dichromatic speckle patterns, and trichromatic speckle patterns are simulated, and the effects of different radius of curved surface on speckle patterns and speckle elongation ratio are discussed. The results show that the larger curvature radius is, the larger speckle elongation becomes, and the smaller the deviation of measured surface roughness is. Therefore, influence of curvature of rough surface on measurement precision should be taken into consideration during measuring process.

Comparison of Surface Roughness Measurement in Dichromatic Speckle Patterns with Autocorrelation Method

2011 ◽  
Vol 189-193 ◽  
pp. 680-683 ◽  
Author(s):  
Zong Heng Yuan ◽  
Yan Hua Zhang ◽  
Jian Wei Zhang ◽  
Ye Fan Ge
Keyword(s):  
Surface Roughness ◽  
Autocorrelation Function ◽  
Correlation Length ◽  
High Reliability ◽  
Laser Speckle ◽  
Roughness Measurement ◽  
Elongation Ratio ◽  
Surface Roughness Measurement ◽  
Speckle Patterns ◽  
Autocorrelation Method

Applying autocorrelation method to process laser speckle patterns, the relation between surface roughness and speckle elongation and correlation length of autocorrelation function can be obtained, and the measured surface roughness can be achieved based on this relation. One-dimension autocorrelation and two-dimension autocorrelation function are used, Moreover, surface roughness is evaluated by speckle elongation and correlation length of autocorrelation function. Aspect ratio of speckle granular represents speckle elongation ratio, which eliminates effects of speckle granular average size on measurement results compared to other methods using before. It has high reliability and efficiency in surface roughness measurement evaluation.

scholarly journals Gradient Correlation Functions in Digital Image Correlation

2019 ◽  
Vol 9 (10) ◽  
pp. 2127 ◽  
Author(s):  
Mikael Sjödahl
Keyword(s):  
Correlation Function ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Correlation Functions ◽  
Laser Speckle ◽  
Image Correlation ◽  
Intensity Correlation ◽  
Intensity Correlation Function ◽  
Speckle Patterns ◽  
The Difference

The performance of seven different correlation functions applied in Digital Image Correlation has been investigated using simulated and experimentally acquired laser speckle patterns. The correlation functions were constructed as combinations of the pure intensity correlation function, the gradient correlation function and the Hessian correlation function, respectively. It was found that the correlation function that was constructed as the product of all three pure correlation functions performed best for the small speckle sizes and large correlation values, respectively. The difference between the different functions disappeared as the speckle size increased and the correlation value dropped. On average, the random error of the combined correlation function was half that of the traditional intensity correlation function within the optimum region.

scholarly journals Different methods for characterizing surface roughness using laser speckle technique

2019 ◽  
Vol 12 (23) ◽  
pp. 21-29
Author(s):  
Mayada B. Al-Quzweny
Keyword(s):  
Surface Roughness ◽  
Speckle Pattern ◽  
Point Of View ◽  
Laser Speckle ◽  
Image Texture ◽  
Object Surface ◽  
Image Texture Analysis ◽  
Measuring Surface ◽  
Wide Range

In this work, results from an optical technique (laser speckle technique) for measuring surface roughness was done by using statistical properties of speckle pattern from the point of view of computer image texture analysis. Four calibration relationships were used to cover wide range of measurement with the same laser speckle technique. The first one is based on intensity contrast of the speckle, the second is based on analysis of speckle binary image,  the third is on size of speckle pattern spot, and the latest one is based on characterization of the energy feature of the gray level co-occurrence matrices for the speckle pattern. By these calibration relationships surface roughness of an object surface can be evaluated within these relations ranges from single speckle pattern image which was taken from the surface.

Surface roughness measurement of aluminium thin film by laser speckle method

2020 ◽  
Author(s):  
R. Balamurugan ◽  
K. Rathina ◽  
A. R. Arul ◽  
S. Inbakumar ◽  
R. G. Sethuraman
Keyword(s):  
Thin Film ◽  
Surface Roughness ◽  
Laser Speckle ◽  
Roughness Measurement ◽  
Surface Roughness Measurement
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