Visualization and fluorescence spectroscopy of fingerprints on glass slide using combined 405 nm laser and phase contrast microscope

Abstract

This work describes the simultaneous visualization and laser fluorescence spectroscopy of patent fingerprints on the glass slide using 405 nm laser and phase contrast microscope (PCM). High resolution images are achieved due to phase shifts conversion as light passes through a transparent specimen such as sweat layer. The residue composition can be identified by fluorescence spectroscopy depending on the wavelength used. Here, only two peaks likely corresponding to sodium chloride at 440 and 460 nm are detected. Application of fluorescein powder was found to enhance the image contrast; however when dissolved by the sweat it can play a role via fluorescence particularly when it is conjugated to appropriate contrast agents.