title: Real-time fingerprint sensor using a hologram.
abstract: A holographic fingerprint sensor has been developed for a system that identifies a person by his or her fingerprints. The sensor uses a laser as its light source and consists of a light-conducting plate, which is a transparent glass plate with a plain grating-type hologram, and a focusing lens system just under the hologram. Since the sensor uses a plane-parallel plate, all the optical paths from each point of a fingerprint to the hologram are equal, and a bright fingerprint can be created without the trapezoidal distortion that is inherent in conventional prism-type sensors.
authors: S
authors: S
authors: Igaki
authors: S
authors: S
authors: Eguchi
authors: F
authors: F
authors: Yamagishi
authors: H
authors: H
authors: Ikeda
authors: T
authors: T
authors: Inagaki