High contrast two-photon imaging of fingermarks

Area of Science:

• Forensic Science
• Optical Imaging
• Biophysics

Background:

• Optically-acquired fingermarks are crucial forensic evidence.
• Current methods like cyanoacrylate fuming and UV fluorescence have limitations, including poor image quality on reflective/scattering surfaces and sample damage.
• Challenges include background scattering, substrate auto-fluorescence, and photo-physical effects.

Purpose of the Study:

• To introduce a novel imaging modality for enhanced fingermark visualization.
• To overcome the limitations of existing techniques for latent fingerprint detection.
• To improve the quality of fingermark images obtained from difficult substrates.

Main Methods:

• Development and application of a near-infrared (NIR), two-photon induced fluorescence imaging modality.
• Utilizing specific wavelengths and excitation mechanisms to target fingerprint residues.
• Imaging fingermarks on nonporous surfaces, including those that are highly reflective or scattering.

Main Results:

• Significantly enhanced quality of fingermark images, particularly on reflective and scattering surfaces.
• Reduced background interference and auto-fluorescence compared to traditional methods.
• Minimized photo-damage to sensitive forensic samples during imaging.

Conclusions:

• The novel NIR, two-photon imaging technique offers a substantial improvement for latent fingermark visualization.
• This method provides higher quality images and better sample preservation for forensic evidence.
• It addresses critical challenges in forensic imaging, enabling more reliable digital recording and analysis.