High-speed cross-sectional imaging of valuable documents using common-path swept-source optical coherence tomography.

Area of Science:

• Optical Engineering
• Metrology
• Document Security

Background:

• Common-path swept-source optical coherence tomography (SS-OCT) offers potential for high-speed and stable optical coherence tomography (OCT) systems.
• Assessing the security features of valuable documents necessitates high-speed imaging techniques capable of capturing cross-sectional details.

Purpose of the Study:

• To investigate the efficacy of a common-path SS-OCT system for cross-sectional imaging of documents.
• To evaluate the impact of high transport speeds on the performance of SS-OCT for document security analysis.

Main Methods:

• An SS-OCT system utilizing a swept source (1335 nm center wavelength, 50 kHz sweep repetition rate) was employed.
• Document samples were translated at speeds up to 2000 mm/s.
• The influence of transport speed on depth resolution and signal intensity was experimentally assessed.

Main Results:

• The common-path SS-OCT system demonstrated capability for cross-sectional imaging of documents at high speeds.
• Experimental results showed signal degradation that aligned with theoretical predictions as transport speed increased.
• Depth resolution and signal intensity were evaluated under various high-speed translation conditions.

Conclusions:

• Common-path SS-OCT is a viable technology for high-speed imaging of documents to verify security features.
• The observed signal degradation at high speeds is consistent with theoretical models, validating the system's performance.