Technical note: A novel 3D scan-based optical method for analyzing lines drawn at different pen pressure.

Area of Science:

• Forensic Science
• Document Examination

Background:

• Pen pressure is a key factor in handwriting analysis and forgery detection.
• Existing methods for analyzing pen pressure can be destructive or costly.

Purpose of the Study:

• To present a novel, non-contact, non-destructive, and affordable technique for measuring groove width in handwriting.
• To investigate the relationship between pen pressure and groove width.
• To assess the impact of different printer types on groove depth.

Main Methods:

• A new non-contact, non-destructive technique was developed to measure groove width.
• Experiments were conducted to measure groove widths under varying pen pressures.
• Written documents were passed through laser, inkjet, and dot matrix printers to observe effects on groove depth.

Main Results:

• The new technique successfully demonstrated clear differences in measured groove widths corresponding to varying pen pressure.
• Passing documents through a laser printer significantly decreased groove depth.
• Inkjet printers caused a minor decrease in groove depth, while dot matrix printers had no detectable effect.

Conclusions:

• The developed technique offers a viable, cost-effective tool for analyzing pen pressure in questioned document analysis.
• Document processing through printers, particularly laser printers, can alter physical evidence like groove depth, impacting forensic analysis.