Quality assessment of laser speckle image sequences for digital image correlation by Sequence-image Quality Evaluation Index

• Published in: Measurement : journal of the International Measurement Confederation 2024-04, Vol.229, p.114486, Article 114486
• Main Authors: Gang, Huang, Wuji, Zhang, Shengnan, He, Yong, Su, Zhiwei, Pan, Shenghong, Huang, Weihua, Wang, Dale, Zhang
• Format: Article
• Language: English
• Subjects: Digital image correlation (DIC); Laser speckles; Sequence-image Quality Evaluation Index (SQEI); Thermal strain
• ISSN: 0263-2241; 1873-412X
• DOI: 10.1016/j.measurement.2024.114486

•SQEI Development: The paper introduces the Sequence-image Quality Evaluation Index (SQEI), a new metric for assessing the quality of laser speckle image sequences in digital image correlation (DIC) applications.•Advantages of SQEI: SQEI is unique in its ability to evaluate not only individual image quality but also the correlation between sequence images. This enhances the accuracy and robustness of DIC measurements in extreme environments.•Experimental Validation: The effectiveness of SQEI is demonstrated through metal thermal strain experiments, analyzing the impact of various external and material factors like laser wavefront, temperature, CCD angle, surface roughness, and reflectivity.•Innovative Methodology: The study innovatively combines speckle quality assessment with sequence correlation, potentially transforming strain measurement practices in challenging conditions. Digital Image Correlation (DIC) with laser speckle is effective for measuring strain in extreme conditions, but its limited resistance to disturbances and decorrelation issues limit its broader use. Addressing this, the Sequence-image Quality Evaluation Index (SQEI) has been introduced. SQEI evaluates laser speckle image sequences by considering individual image quality and their correlation. It improves upon previous standards by confirming speckle image quality for DIC accuracy and removing decorrelated images, enhancing DIC's precision and durability. Verified through metal thermal strain experiments, SQEI assesses the impact of factors like laser wavefront, temperature, and CCD angle. The results confirm SQEI's efficacy in evaluating laser speckle quality and guiding the optimization of optical devices, thus significantly boosting the accuracy and efficiency of DIC strain measurement with laser speckles.