Forensic Optical Evaluation of Chinese Seal Impressions
Optical seal evaluation establishes chop authenticity through microscopic tool marks, spectral luminescence, and stroke intersection depth profiles before PRC courts.
3d Optical Profilometry
Meaning
Non-contact surface metrology represents the primary class of industrial quality control used to measure sub-micron finishes and three-dimensional topography of precision manufactured parts. In high-value supply chains, 3d optical profilometry uses light interference or confocal scanning to capture microscopic deviations without touching the specimen. This approach prevents the surface deformation that occurs during traditional stylus measurements.
The resulting scan provides a highly accurate map of seal interfaces, precision molds, or stamped components.
Technical Execution
Optical interference forms the underlying mechanism of the measurement process. When the system directs a divided light beam toward both a reference mirror and the sample surface, the recombined waves produce interference patterns that correspond to height variations. These patterns translate into precise numerical data representing surface roughness and spatial coordinates.
Variations in material reflectivity are handled by adjusting the detector exposure or using multi-wavelength sources. The technique avoids mechanical friction and measures delicate materials like polymer seals without surface damage.
Forensic Application
Authentication audits of physical contracts rely on sub-micron measurements to resolve sequence conflicts on documents. In cases where signature ink and corporate seals overlap, 3d optical profilometry measures the height profiles of the crossed lines to determine which mark sits on top of the other. Because a stamped chop leaves a measurable layer of pigment or deforms the paper fibers in a specific direction, analyzing the micro-topography reveals the chronological order of execution.
This non-destructive method preserves the integrity of disputed contracts while providing clear physical evidence for forensic examiners.
Regulatory Standard
Compliance guidelines in industrial audits require structured calibration protocols to ensure measurement repeatability. The international standard ISO 25178 governs the acquisition of these metrics. In administrative courts, forensic scans must follow national standards to be admitted as certified evidence.