Abstract

Digital image correlation (DIC) is a popular, noncontacting technique to measure full-field deformation by using cameras to track the motion of an applied surface pattern. Because it is noncontacting, DIC can be performed for extreme temperature applications (e.g., hot-fire rocket testing of carbon composite rocket nozzles) under harsh conditions during which bonded gauges are damaged. Speckle pattern inversion is a phenomenon that sometimes occurs while performing high-temperature DIC. During speckle pattern inversion, portions of the surface pattern that were initially darker at room temperature (e.g., graphite) may emit more light due to blackbody radiation than the portions that were initially paler, thereby producing images in which the pattern appears inverted at high temperature relative to the initial pattern at room temperature. This phenomenon can prevent the correlation algorithm from being able to resolve the displacements between images. This work compares three methods to mitigate speckle pattern inversion: (A) the subtraction method, a recently-published technique in which two high-temperature images are subtracted to remove unwanted light; (B) the filtering method, a popular technique in which optical bandpass filters screen out unwanted light; and (C) the histogram rescaling method, a proposed new method that pairs a color camera with a blue light source and uses information from the green sensor of the camera to correct against inversion in the blue sensor through postprocessing. The histogram rescaling method is shown to successfully eliminate speckle pattern inversion and has the added advantages that it does not require quasi-static loading to be able to compensate for speckle pattern inversion, nor does it impose thick-glass distortions caused by the optical filter.

© 2022 Optica Publishing Group

High-temperature stereo-digital image correlation using a single polarization camera

Bin Chen, Lei Ji, and Bing Pan
Appl. Opt. 59(13) 4008-4015 (2020)

Heatwave distortion correction using an improved reference sample compensation method and multispectral digital image correlation

Xiaoying Zhang, Chenzhuo Li, Liping Yu, and Bing Pan
Appl. Opt. 60(13) 3716-3723 (2021)

High-speed stereo-digital image correlation using a single color high-speed camera

Liping Yu and Bing Pan
Appl. Opt. 57(31) 9257-9269 (2018)

High-temperature thermal disturbance elimination method based on multi-channel extraction and correction

Wanlin Pan, Qianshan Liu, Junrui Li, Xiaokang Fan, Lei Zhou, and Yonghong Wang
Appl. Opt. 63(2) 367-376 (2024)

Method to eliminate thermal disturbance errors in digital image correlation measurement based on projection speckle

Huanqing Wang, Yonghong Wang, Yilei Zhu, Fangyuan Sun, Shuangle Wu, and Qihan Zhao
Appl. Opt. 59(33) 10474-10482 (2020)