Optical system for biometric identification of a user
The present disclosure relates to the field of biometric identification of a user, in particular, to a system and method of identifying a user. The method of identifying a user includes: detecting a portion of a user's finger in contact with a touch-sensitive region of a device; and collecting data relating to a fingerprint of the user from the user's finger for a period of time and obtaining a plurality of frames from the data. The method further includes determining whether the user is an authorized user of the device, based on a ridge pattern, a sweat gland pattern, and dynamics of blood circulation in the user's finger as indicated by the data. The method provides an enhanced security system that can be integrated in a user's mobile device to protect against fake biometric characteristics in access control systems.
1. An optical system integrated in a mobile device and comprising:
a waveguide configured to guide light emitted by a radiation source;
an optical image forming unit comprising at least one lens configured to receive light exiting the waveguide and reflected from a light scattering object, wherein the at least one lens focuses the received light onto a polarizing film;
the polarizing film configured to filter the received light;
a detector having light-sensitive elements which sense light transmitted by the polarization film and form an optical image on a surface of the detector based on the sensed light, wherein the detector is configured to convert the formed optical image into an electrical signal comprising data relating to the light scattering object, wherein the data relating to the light scattering object comprises dynamics of blood circulation in the light scattering object; and
at least one processor configured to obtain a plurality of frames from the data relating to light scattering object and to identify a user by comparing the data relating to the light scattering object with pre-stored data, based on an analysis of spatio-temporal intensity fluctuations of moving blood cells observed in the plurality of frames obtained from the data relating to light scattering object,
wherein the waveguide comprises a light absorber disposed on a side surface of the waveguide.
2. The optical system of claim 1 , wherein the at least one processor is further configured to identify the user as an unauthorized user in response to determining a portion of a ridge pattern does not match a portion of a pre-stored reference ridge pattern, determining a sweat gland pattern does not match a pre-stored reference sweat gland pattern, or determining blood is not circulating in the light scattering object.
3. The optical system of claim 1 , wherein the light scattering object is a user's finger.
4. The optical system of claim 3 , wherein the electrical signal contains information on a ridge pattern, a sweat gland pattern, and dynamics of blood circulation in the user's finger.
5. The optical system of claim 1 , wherein the polarizing film comprises cross-polarization part and a co-polarization part.
6. The optical system of claim 1 , wherein the light scattering object is placed adjacent to the waveguide.
7. The optical system of claim 1 , wherein the polarizing film is disposed in front of the detector along a light path.
8. The optical system of claim 1 , wherein the radiation source is either a laser diode or a light emitting diode (LED).
9. The optical system of claim 1 , wherein the light absorber is disposed on the side surface of the waveguide that is opposite to the radiation source and adjacent to the detector.
10. The optical system of claim 1 , wherein the at least one lens of the optical image forming unit includes at least one of a single lens, a set of lenses, and an array of lenses.
11. The optical system of claim 1 , wherein the detector of the optical image forming unit is a CMOS array.
12. The optical system of claim 1 , wherein the at least one processor is autonomous.
13. The optical system of claim 1 , wherein the at least one processor is a cluster system.
14. The optical system of claim 1 , further comprising a plurality of waveguides and a plurality of radiation sources.