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| Non-Destructive Measurement of High-Aspect-ＲatioMicroholesBased on Coaxial Laser Imaging and Image-Feature Ｒegression#br# |
| LIANG Guangheng，CAO Mengyi，LI Boyao *
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| Dongguan University of Technology，Dongguan 523000，China |
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Abstract Targeting micro blind holes with diameters of 0．1～1．0 mm and aspect ratios within 10，this paper
proposes a non-destructive measurement method based on coaxial laser illumination，single-frame imaging，and
image-feature regression．The laser beam is delivered coaxially with the objective through a beam splitter to the
hole bottom，and the reflected light returns along the same axis to the CMOS camera for single-exposure
acquisition．Without z-axis scanning，we extract robust features compatible with the reflection model-such as the
annular bright band，gradient/symmetry cues，and gray-level textures-and build a physics-aware regression from
image features to depth，thereby outputting depth，diameter and aspect ratio． The algorithm automatically
suppresses granular interference and glare，supports ＲOI auto-localization and outlier rejection，and is
integrated into a GUI for batch measurement and one-click reporting．Experiments on stainless-steel blind-hole
arrays(0．1/0．2/0．3 mm)demonstrate tens-of-micrometers accuracy and stable consistency with third-party
metrology，indicating good engineering applicability for array-level online inspection．
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Published: 25 February 2026
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