Detection and mapping of latent fingerprints by laser-induced breakdown spectroscopy

Detection of latent fingerprints on a Si wafer by laser-induced breakdown spectroscopy (LIBS) is demonstrated using approximately 120 fs pulses at 400 nm with energies of 84 +/- 7 microJ. The presence of a fingerprint ridge is found by observing the Na emission lines from the transferred skin oil. The presence of the thin layer of transferred oil was also found to be sufficient to suppress the LIBS signal from the Si substrate, giving an alternative method of mapping the latent fingerprint using the Si emission. A two-dimensional image of a latent fingerprint can be successfully collected using these techniques.