Biometric authentication device
A biometric authentication device of the present invention includes a light guide layer on which a light diffusion unit for displaying an aerial image representing a design of a living body at a height is formed, a light source that irradiates the light guide layer with light, a polarized beam splitter disposed on an upper surface side of the light guide layer, a retroreflective layer disposed on a bottom surface side of the light guide layer, and an imaging camera that captures an image of a living body superimposed on the aerial image through an opening formed in the retroreflective layer, and performs biometric authentication based on an image captured by an imaging camera.
1. A biometric authentication device with a function of displaying an aerial image using retroreflection, the biometric authentication device comprising:
a light guide layer on which a design for the aerial image is formed;
a light source that irradiates the light guide layer with light;
a polarization beam splitter disposed on one principal surface side of the light guide layer;
a retroreflective layer disposed on a side of the other principal surface of the light guide layer, the other principal surface facing the one principal surface; and
an imaging unit that captures an image of a living body in the vicinity of a region where the aerial image is displayed via an opening formed in the retroreflective layer;
wherein the biometric authentication device performs biometric authentication based on the image captured by the imaging unit; and,
wherein a polarization filter having a polarization direction different from that of the polarization beam splitter is provided at a position matching the opening.
2. The biometric authentication device according to claim 1 , wherein the polarization direction of the polarization filter is orthogonal to a polarization direction of the polarization beam splitter.
3. The biometric authentication device according to claim 1 , wherein the imaging unit captures an image of a living body at a time when the light source is turned off.
4. The biometric authentication device according to claim 3 , wherein display of the aerial image and imaging of the imaging unit are time-divisionally controlled.
5. The biometric authentication device according to claim 1 , wherein the imaging unit includes an infrared camera, and a visible light filter that shields visible light is provided at a position matching the opening.
6. The biometric authentication device according to claim 1 , wherein the aerial image is generated at a position symmetrical to the design with respect to a surface of the polarization beam splitter, and a focal point of the imaging unit is adjusted to a position of the aerial image.
7. The biometric authentication device according to claim 1 , further comprising: an output unit that notifies the user that imaging by the imaging unit has ended.
8. The biometric authentication device according to claim 1 , wherein the living body is a fingerprint or a vein.