J. Eur. Opt. Society-Rapid Publ. 2026, 22, 21 Ó The Author( s), published by EDP Sciences, 2026 https:// doi. org / 10.1051 / jeos / 2026015 Available online at: https:// jeos. edpsciences. org
Journal of the European Optical Society-Rapid Publications
RESEARCH ARTICLE
Characterization of subsurface damage in fused silica using non-destructive optical coherence tomography and a destructive approach by iterative plasma jet etching
Samson Frank 1, Heike Müller 2, Wei Zhang 1, Dennis Thelemann 1, Thomas Arnold 2, 3, and Jens Bliedtner 1
1 |
EAH Jena University of Applied Sciences, Department SciTec, Carl-Zeiss-Promenade 2, 07745 Jena, Germany |
2 |
Leibniz Institute of Surface Engineering( IOM), Permoserstraße 15, 04318 Leipzig, Germany |
3 |
Institute of Manufacturing, TU Dresden, 01062 Dresden, Germany |
Received 25 November 2025 / Accepted 8 February 2026
Abstract. In this work, a Vickers indenter was used to systematically produce defined and artificial indentations on the surface of fused silica glass to systematically study subsurface damage( SSD). Various measurement methods, such as optical microscopy, white light interferometry( WLI) and optical coherence tomography( OCT), were used to examine SSD depths and morphologies. Tomographic OCT measurements were performed to non-destructively characterize the defects. SSD depths were validated with a destructive preparation method using iterative plasma jet etching( PJE) and subsequent topography measurements with WLI. A total of eight PJE steps were performed to successively remove material, opening and widening surface and subsurface defects. SSD depths in this destructive characterization approach were deduced by combining the PJE etching depth and the corresponding surface roughness parameter Sv. Additionally, measurement methods were verified twice through OCT measurements performed after different etching steps. The increased surface roughness from PJE reduced OCT imaging artifacts and improved the OCT measurement accuracy. The final SSD depth, determined by adding the OCT-measured SSD values after PJE process to the respective PJE etching depth, was highly reliable. The SSD depth of the Vickers indentation determined by the combined use of OCT and PJE showed excellent agreement with the SSD depth estimated using a commonly applied empirical formula for Vickers indentations, providing additional confirmation of the SSD depth and further demonstrated the robustness of the combined OCT-PJE approach.
Keywords: Vickers-indented subsurface damage, Optical glass, Fused silica, Optical coherence tomography, Plasma jet etching.
1 Introduction
Subsurface damage( SSD) is commonly induced during abrasive machining processes such as grinding and lapping. The resulting microcracks, dislocations and residual stress critically affect the performance and reliability of optical components, especially in high-precision or high-power applications [ 1 – 7 ]. Characterization and control of SSD are essential in the optical fabrication process. In recent decades, extensive research has been carried out on the evaluation of SSD using predictive models and measurement techniques, including both destructive and non-destructive methods [ 8 – 35 ]. A commonly used destructive method involves polishing a tapered section to expose the damaged layer, which is then analyzed under a microscope [ 1, 28, 36 ].
* Corresponding author: samson. frank @ eah-jena. de
However, destructive evaluation is time-consuming and lacks the flexibility for real-time or location-specific measurements [ 37 ]. Alternative non-destructive tools such as laser-based scattering, acoustic microscopy, fluorescence imaging, x-ray diffraction, and optical coherence tomography( OCT) have also been employed. Each of these methodsoffersdistinctstrengthsbutalsolimitations [ 36, 38 – 49 ].
Initially developed for biomedical diagnostics, OCT has become a non-destructive tool for subsurface evaluation in a wide range of materials, particularly ceramics and optical glasses [ 29, 35 – 37, 50 – 60 ]. In a previous work [ 37 ], the application of OCT for visualizing the three-dimensional structure of SSD was demonstrated, enabling quantitative analysis of their depth, distribution and damage morphology – critical factors for process optimization and quality control in optical manufacturing [ 37, 61, 62 ]. SSD detection using OCT can be limited by imaging artifacts. In regions of
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