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J. Eur. Opt. Society-Rapid Publ. 22, 51( 2026)
Figure
6. Comparison of calculated IF mean and the slope S VV, which is used to obtain the SSD depth after PJE given for Sample # 1.
Figure
7. Comparison of calculated IF mean and the slope S VV, which is used to experimentally obtain the SSD depth after PJE given for Sample # 2. In contrast to the previous example, here the etching steps are significantly larger.
The calculation principle is shown below for another Vickers indentation of Sample # 2( see Fig. 7). In this case, higher etching removal is achieved for each process step, so that the maximum of the slope and IF can already be seen in the second etching step. Nevertheless, the IF max corresponds to the maximum slope at an etching depth d 27 lm, and according to equation( 6), a value SSD = 52.47 lm is determined.
In addition, IF can be used to generate a 3D representation of the SSD structure. As explained in Section 3.2, the measured surface topography data z exp for IF > threshold are combined in a height map, taking into account the corresponding removal depths d. Figures 8A and 8B show the results for the indentations of Sample # 1 and Sample # 2 for IF > 1.5. Both indentations exhibit a prominent ring structure located in a depth of approx. 10 – 15 lm. These features indicate the presence of a cone crack which mainly contributes to SSD in the samples investigated. Here, the material is distorted resulting in sudden lateral expansion. This abrupt widening might be due to a combination of chemical etching attack and gas flow. Such cone cracks could be verified by OCT measurements and are particularly noticeable for Sample # 1 as shown in Figure 8C. OCT measurements given in Figures 8C and 8D were provided for comparison by the University of Applied Sciences in Jena.
The IF threshold used to determine surface height data is moderately sensitive. However, a useful range is to be identified that should be used to obtain valid results. To substantiate this in more detail, the height of distinctive SSD features for Sample # 2 are compared in Figure 9 for different IF values. ItisevidentthatforIF > 1.1 and IF > 1.25 shown in Figures 9A and 9B artifacts from the measurement and a lack of alignment accuracy occur at a z height of approx. �27 lm. Otherwise, if the threshold is set too high( Fig. 9D for IF > 1.8), information about the