A novel optical system of fingerprint and finger vein images acquisition

Abstract

Due to the biological multi mode identification technology, a novel fingerprint and finger vein multiple images acquisition optical system is developed and described. The fingerprint and finger vein imaging systems contain respectively 3 and 12 spherical lenses, which work at 650nm and 850nm wavelength with a 640×480 CCD and a 640×512 uncooled IR detector as the imaging devices. With the aid of ZEMAX software, the optical systems were designed and optimized to cause a good imaging quality. The MTF value of the fingerprint imaging lens is above 0.6 at 67lp/mm, while the finger vein imaging lens is above 0.8 at 30lp/mm. The spot diagrams’ RMS radiuses of the two lenses are all much smaller than the detectors’ pixel size, which are close to the diffraction limit. Both the two lenses have distortions less than 0.5%. The experiments proved that this optical system has the merits of fine image quality and high resolution with compact structures and low cost.