“…The wavelength of the emitted photon will depend on the energy levels of the activator and generally in OSL materials, the emission wavelength is lower than the stimulation wavelength. The effect of this process, even lying on a different physical mechanism, is therefore similar to that seen in up-conversion materials but the stimulation can be easily performed also by common and low-cost light emitting diodes (LEDs) and few mw/cm 2 as stimulation light power density [ 23 , 24 ]. Another great advantage of OSL in latent fingerprint development is that enables to dramatically expand the range of available phosphors, enabling researchers to find the best option in terms of emission efficiency, particle size, chemical composition and surface properties [ 18 ].…”