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J. Eur. Opt. Society-Rapid Publ. 22, 21( 2026)
Figure
7. Color-coded depth maps of the subsurface damage determined by OCT-measurements for Vickers indentation R2-C4( HV0.5):( A) initial state,( B) after PJE step # 3, and( C) after PJE step # 5.
Table 2. SSD depths of Vickers indentations( HV0.5 and HV0.6) measured by OCT considering the PJE removal depth at various processing steps.
|
|
HV0.5 |
HV0.6 |
SSD depth( lm) measured with OCT for different processing states |
initial |
32.3 ± 14.6 |
44.2 ± 14.5 |
|
after PJE # 3 |
31.1 ± 3.7 |
36.4 ± 6.7 |
|
after PJE # 5 |
30.8 ± 4.7 |
35.2 ± 6.2 |
Figure 8. Determination of SSD depth after PJE:( A) Etch dependency of void volume and slope determination for three indentations.( B) Etching depth and Sv of the maximum slope position.
Thus, the SSD depth can be estimated by taking the Sv value measured at the etching depth d where the maximum slope of VV occurs, as indicated by equation( 5):
SSD ½ lm Š ¼ Sv fmax ðslopeVV
Þg þ d fmax ðslopeVV
Þg: ð5Þ
Based on this calculation, the SSD depth is determined for the four selected columns. The results are compared in Figure 9 with the SSD depth values measured by OCT in the initial state, after PJE # 3 and PJE # 5. The OCT results obtained after PJE are in better agreement with the values calculated by equation( 5). This is mainly caused by surface roughening and suppression of OCT measurement artifacts, thus yielding a higher accuracy.
However, deep etching is not beneficial for a higher precision of the OCT measurements. After PJE # 5 SSD is only measurable on a few indentation positions( see reduction of
Figure 9. SSD depth measured with OCT in comparison to SSD depth determination based on surface roughness Sv value and applying equation( 5).( n indicates the number of measurements each column).