Abstract: Disclosed is an optical fingerprint acquisition apparatus capable of reducing an image distortion and a size of an optical system by deforming the shape of a prism. The prism according to the invention includes a fingerprint contacting surface to be touched by a fingerprint of a person, a totally reflecting surface facing the fingerprint contacting surface with an angle &thgr; for totally and inwardly reflecting the light scattered from the fingerprint in contact with the fingerprint contacting surface, a primarily projecting/re-incident surface linking the fingerprint contacting surface to the totally reflecting surface with an angle &phgr; for primarily projecting the light totally reflected from the totally reflecting surface so as to be re-incident from outside, and an ultimately projecting surface facing the primarily projecting/re-incident surface for ultimately projecting the light re-incident to the primarily projecting/re-incident surface toward outside.

Abstract: Disclosed is an optical fingerprint acquisition apparatus capable of reducing an image distortion and a size of an optical system by deforming the shape of a prism. The prism according to the invention includes a fingerprint contacting surface to be touched by a fingerprint of a person, a totally reflecting surface facing the fingerprint contacting surface with an angle &thgr; for totally and inwardly reflecting the light scattered from the fingerprint in contact with the fingerprint contacting surface, a primarily projecting/re-incident surface linking the fingerprint contacting surface to the totally reflecting surface with an angle &phgr; for primarily projecting the light totally reflected from the totally reflecting surface so as to be re-incident from outside, and an ultimately projecting surface facing the primarily projecting/re-incident surface for ultimately projecting the light re-incident to the primarily projecting/re-incident surface toward outside.