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Laser-Induced Visualization of Latent Fingerprints on Metal Surfaces
Haolin Guo1, Yongfeng Qian1, Hong An1
1Key Laboratory of CNC Equipment Reliability, Ministry of Education, School of Mechanical and Aerospace Engineering, Jilin University, Changchun, 130022, China.
Small (Weinheim an Der Bergstrasse, Germany)
|August 4, 2025
Summary
This study introduces a novel laser technique to rapidly visualize latent fingerprints (LFPs) on metal surfaces. The method enhances fingerprint contrast and durability, offering a significant advancement for forensic investigations.
Area of Science:
- Forensic Science
- Materials Science
- Surface Chemistry
Background:
- Latent fingerprints (LFPs) are crucial in criminal investigations.
- Visualizing LFPs on metal surfaces presents significant challenges.
- Existing methods often lack speed, accuracy, or broad applicability.
Purpose of the Study:
- To develop a rapid, one-step laser-based method for visualizing LFPs on metal surfaces.
- To enhance the recognizability and pattern fidelity of visualized LFPs.
- To assess the method's applicability across various metal types and surface roughness levels.
Main Methods:
- A one-step laser irradiation technique was applied to metal surfaces with latent fingerprints.
- Gray value analysis was used to quantify optical contrast between fingerprint ridges and valleys.
- Orientation field analysis evaluated the texture quality and pattern fidelity of visualized LFPs.
Main Results:
- Laser irradiation significantly improved the optical contrast of LFPs by inducing differential oxide deposition.
- Fingerprint ridges showed reduced oxide accumulation compared to valleys, enhancing ridge-valley contrast.
- Visualized LFPs demonstrated excellent abrasion resistance and broad applicability on diverse metal surfaces.
Conclusions:
- The developed laser-based method provides rapid and accurate visualization of LFPs on various metal surfaces.
- This technique offers enhanced recognizability, pattern fidelity, and durability of fingerprint evidence.
- The study presents a robust and versatile tool with transformative potential for forensic science.
