Predictive Quality Control / solino Application note ^)tO100-SO-50-MAN-001 Coins and Precious Metal Surfaces Anomaly Opto solino RTI sensorDetecting micro defects and surface irregularities using BRDF computational imaging Customer Task: Inspection Challenges: Coins, medals and precious metal products require extremely high surface quality standards. In minting processes and precious metal production, even very small surface defects can reduce the value, appearance and authenticity of the final product. Manufacturers require reliable inspection methods for: • minted coin surfaces • engraved structures and micro-details • reflective precious metal finishes • security and authenticity features • surface contamination or mechanical damage The goal is to detect surface defects early in the production process and ensure consistent quality. Inspecting coin surfaces and precious metal finishes presents several challenges for conventional machine vision systems. Typical challenges include: • highly reflective metal surfaces such as silver or gold • complex engraved microstructures • decorative surface textures and fine radial patterns • small scratches, dents or contamination • changing reflections depending on illumination direction Standard camera systems rely on fixed lighting conditions and often fail to reveal subtle surface irregularities. Strong reflections can hide defects or make inspection results inconsistent. As a result, many inspections still rely on manual visual inspection performed by trained operators. Fig. 2: 100-SO-50-MAN-001 solino 50x50 - Viewer - Stand Opto GmbH

Technology Principle Typical inspection targets include: • coin engravings and relief structures • fine radial surface textures • lettering and microstructures • reflective precious metal finishes • surface contamination or handling damage The solino RTI sensor uses BRDF-based computational imaging to reveal surface structures. Within milliseconds the system captures a series of images under different illumination angles and reconstructs the surface reflectance information computationally. 64 multi-directional LED illumination photometric stereo image capture reflectance-based surface reconstruction...