Visualization of latent fingermarks on rough aluminum surfaces

What is it about?

Detection and visualization of fingermarks on rough surfaces is a challenging task. Using sequential deposition of a thin layer of gold and zinc-based compounds, we succeeded in developing latent fingermarks on scratched and rough aluminum surfaces. We found that the best image enhancement appeared with the Au and ZnS coatings. Using this combination, we could enhance the visibility of latent fingermarks aged over two months under normal temperature and pressure conditions. The optical properties like reflectance from the fingermarks and deposited layers were analyzed using the transfer matrix method. The calculations showed that the Au (~ 10 nm) and ZnS (~ 170 nm) bi-layer combination has a higher reflection contrast at the green wavelength, near the maximum spectral sensitivity of the human eye which results in the improved visualization of the fingermarks.

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