An in-situ scratch tester under the confocal laser scanning microscope (CLSM)

For in-situ scratch tests, real time and high resolution observation is the ultimate goal. In-situ scratch tests inside the scanning electron microscope (SEM) or transmission electron microscope (TEM) could provide a relatively high imaging resolution but require a low refresh rate, and in-situ scratch tests under the ordinary optical microscope could employ a relatively high refresh rate but the imaging resolution is low. Alternatively, the confocal laser scanning microscope (CLSM) can provide a balanced performance in both the imaging resolution and refresh rate. Accordingly, a miniaturization scratch tester with dimensions of 170 mm × 80 mm × 80 mm was developed for performing in-situ scratch testing under a commercial CLSM. Its structure and working principle were discussed, followed by characterizing the performance by experiments. In-situ scratch tests of three typical materials, fused silica, ITO thin film deposited on glass, and polymethylmethacrylate (PMMA) were conducted to demonstrate the feasibility of the proposed scratch tester. The dynamic cracking process of fused silica and ITO thin film deposited on glass, and the ductile deformation behavior of PMMA were analyzed according to the in-situ observed results. This study provides a new experimental tool for investigating the deformation and damage processes of transparent materials. •An in-situ scratch tester being compatible with confocal laser scanning microscope was developed.•In-situ observation of the scratching process was achieved by using the scratch tester.•The damage characteristics of fused silica were elucidated according to the in-situ observed results.•A clover-shape shadow was observed in the scratching process of PMMA.