KR20190075026A - Recognition apparatus of fingerprint based optical coherence tomography - Google Patents

Abstract

According to an embodiment of the present invention, a fingerprint recognizing apparatus based on an optical coherence tomography comprises: a case having an inner space, and a transparent thin film having a fingerprint of a subject to be measured to be in contact therewith, at one side thereof; an image sensor disposed at the other side of the case, and generating a signal for obtaining a hyperspectral image of the subject to be measured; a light source for providing light for a region of the transparent thin film where the signal reaches from the image sensor, separately from the signal of the image sensor, and mounted on the inner space or one wall of the case; and a phase modulation unit for providing the signal generated by the image sensor for a path oriented to the transparent thin film, reflecting a part of the signal generated by the image sensor, and modulating a phase of the other part to reflect the same so as to obtain interference pattern information. The phase modulation unit includes: a fixed reflective mirror for reflecting a part of the signal generated by the image sensor, and fixed in position; a movable reflective mirror for reflecting the other part of the signal generated by the image sensor; and a moving stage for relatively moving the movable reflective mirror with respect to the fixed reflective mirror in a direction perpendicular to a reflective surface of the movable reflective mirror. A phase difference is generated between a part of the signal reflected from the fixed reflective mirror and the other part of the signal reflected from the movable reflective mirror by movement of the movable reflective mirror.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a fingerprint-based optical coherence tomography

A light interferometer tomography-based fingerprint recognition device is disclosed. More particularly, the present invention relates to an optical interferometer tomography apparatus capable of acquiring an interfering signal by phase-modulating a part of a signal from an image sensor while optical interferometry is performed, and acquiring optical interferometry tomographic information of a fingerprint of a measurement subject by Fourier- A shooting-based fingerprint recognition apparatus is disclosed.

Fingerprint recognition is a method of biometrics. It is an authentication method that extracts different fingerprint information for each individual and informs them. Since fingerprints made from the dermis, which is the subcutaneous layer of the skin, have characteristics that do not change forever unless the dermis is damaged, fingerprint recognition has long been used as a method of recognizing individual persons. However, there is a limitation that it is difficult to recognize fingerprints when they are worn out due to labor, or when they are dried.

Generally, a fingerprint recognition method includes a method of printing using ink, and a method of detecting an external fingerprint using a laser scanner. Recently, fingerprint recognition technology based on optical interferometry has been introduced.

In general, the fingerprint recognition device using these methods obtains the fingerprint pattern information of the external fingerprint layer, and inquires the identity of the person to be measured. However, since the fingerprint of a person who has burns, abrasions, or drowning is damaged, There is a difficulty in doing. In order to solve such difficulties, optical coherence tomography apparatuses and the like have been introduced in Korean Patent Application No. 2009-0021669, but the miniaturization is limited due to the complicated optical system structure.

An object of an embodiment of the present invention is to acquire an interference signal by phase-modulating a part of a signal generated from an image sensor while diverging light from a light source toward a transparent thin film where a fingerprint is located, Which can acquire optical interferometry tomographic information of a fingerprint of a finger, and a smart device having the same.

Another object of the present invention is to provide an optical interferometric tomography-based fingerprint recognition system capable of accurately and reliably performing an identification inquiry using information of the inner fingerprint layer even if the outer fingerprint layer of the measurement subject is damaged, And a smart device having the same.

The optical interferometer tomography-based fingerprint recognition apparatus according to the present invention includes a case having a transparent space in which a fingerprint of a subject to be measured comes into contact with an inner space; An image sensor disposed on the other side of the case and generating a signal for acquiring an ultrasound image of a measurement object; A light source for providing light to an area of the transparent thin film to which the signal from the image sensor reaches, separately from the signal of the image sensor, the light source mounted in the inner space of the case or a wall of the case; And a phase control unit for controlling the phase of the signal to generate the interference fringe information by reflecting a part of the signal generated from the image sensor and modulating and reflecting the phase of another part of the signal generated from the image sensor, A modulation unit; Wherein the phase modulating unit includes: a fixed reflection mirror that reflects a part of the signal generated from the image sensor and has a fixed position; A moving reflective mirror that reflects another portion of the signal generated from the image sensor; And a moving stage that relatively moves the moving reflecting mirror relative to the fixed reflecting mirror in a direction perpendicular to the reflecting surface of the moving reflecting mirror, wherein movement of the moving reflecting mirror causes the moving direction of the signal reflected from the fixed reflecting mirror A phase difference is generated between the part and another part of the signal reflected from the moving reflecting mirror.

The light source may include a donut-shaped light source case; And a plurality of diverging members disposed along the periphery of the light source case and diverging light toward the transparent thin film, wherein a signal generated from the image sensor through the hollow region of the light source case is provided in the direction of the transparent thin film .

In addition, the light source may be biased to one side between the phase modulator and the transparent thin film to provide light to the region of the transparent thin film from which the signal from the image sensor arrives.

In addition, the light source may be arranged to have a polygonal structure in the horizontal direction between the phase modulator and the transparent thin film to provide light to the region of the transparent thin film to which the signal from the image sensor reaches.

According to an embodiment of the present invention, an interference signal is obtained by phase-modulating a part of a signal generated from an image sensor while diverging light from a light source toward a transparent thin film on which a fingerprint is positioned, and Fourier- The optical interferometer tomographic information of the optical interferometer can be obtained.

In addition, according to the embodiment of the present invention, even if the external fingerprint layer of the measurement subject is damaged, the identification information can be accurately and reliably performed using the information of the internal fingerprint layer.

In addition, according to the embodiment of the present invention, a supersonic spectral image having excellent spectral resolution and spectral bandwidth can be obtained through the Fourier transform without applying a substance such as a dispersion medium, and slimming of the apparatus can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating an internal configuration of a conventional optical interferometric tomography-based fingerprint recognition apparatus according to an embodiment of the present invention.
2A to 2C are views showing various examples of the light source shown in FIG.
FIG. 3 is a view for explaining the principle of fingerprint recognition of the apparatus shown in FIG.
FIG. 4 is a schematic view illustrating an internal configuration of an optical interferometer tomography-based fingerprint recognition apparatus according to another embodiment of the present invention.
FIG. 5 is a diagram showing a state in which the device shown in FIG. 4 is applied to a smart device.
FIG. 6 is a schematic view illustrating an internal configuration of a conventional optical interferometric tomography-based fingerprint recognition apparatus according to another embodiment of the present invention. Referring to FIG.

Hereinafter, configurations and applications according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION The following description is one of many aspects of the claimed invention and the following description forms part of a detailed description of the present invention.

In the following description, well-known functions or constructions are not described in detail for the sake of clarity and conciseness.

FIG. 1 is a schematic view illustrating an internal configuration of a fingerprint image sensing apparatus based on an optical interferometric tomography according to an embodiment of the present invention. FIGS. 2A to 2C are views showing various examples of the light source shown in FIG. 1, FIG. 3 is a view for explaining the principle of fingerprint recognition of the apparatus shown in FIG.

As shown in FIG. 1, the optical interferometer tomography-based fingerprint recognition apparatus 100 according to an embodiment of the present invention detects a fingerprint image by using the information of the internal fingerprint layer even if the external fingerprint layer of the measurement subject is damaged. A case 110 in which a transparent thin film 115 having an inner space and having a fingerprint 101 of a subject to be measured is disposed on one side thereof and a case 110 for obtaining a superspectral image, A light source 130 for providing light to a region of the transparent thin film 115 to which a signal generated from the image sensor 120 arrives; And a phase modulating unit 150 for obtaining a fringe pattern information by reflecting a part of the wavefront by modulating the phase with respect to the other part.

A first lens 141 may be provided between the image sensor 120 and the phase modulator 150 and a second lens 145 may be provided between the phase modulator 150 and the light source 130.

With this configuration, optical interferometry tomographic information on the fingerprint 101 can be obtained through the interference signal based on the interference fringe information while the optical interference is occurring.

First, as shown in Fig. 1, the case 110 of the present embodiment is formed in a shape of a letter "A" whose central portion is entirely broken, have. The image sensor 120 is mounted on one side of the case 110, the transparent thin film 115 is mounted on the other side, and the phase modulator 150 is mounted on a central portion where the transparent thin film 115 is bent. Therefore, a signal generated from the image sensor 120 can be provided to the transparent thin film 115 through the phase modulating part 150. [

On the other hand, the image sensor 120 of the present embodiment is used for a technique for acquiring hyperspectral images. The image sensor 120 includes a photodetector for obtaining point information, a line image camera for obtaining line information, An image camera may be included. With this configuration, it is possible to acquire hyperspectral images corresponding to points, lines, and surfaces of the measurement target, for example, the fingerprint 101.

In addition, a 2D scan can be performed through a photodetector to obtain an ultrasound image corresponding to point information, and a 1D scan can be performed through a line image camera, thereby obtaining an ultrasound image corresponding to the line information.

The phase modulator 150 of the present embodiment reflects a part of the wavefront of the signal from the image sensor 120 that has passed through the first lens 141 and modulates the phase of the wavefront of another part of the wavefront, 120 can be generated as an interference signal having an interference fringe.

1, the phase modulating unit 150 includes a fixed reflecting mirror 151 that reflects a part of a wavefront of a signal generated from the image sensor 120 and a movable mirror 151 that is movable with respect to the fixed reflecting mirror 151. [ And move reflective mirrors 155 that are arranged to generate a phase difference with respect to another portion of the signal, i.e., phase-modulate.

Here, the movable reflecting mirror 155 can be mounted on the moving stage 157 and linearly moved in the direction of the arrow in Fig. However, it is needless to say that the moving structure of the moving reflecting mirror 155 is not limited to this, and it is possible to have a tilting structure as well as being movable in the lateral direction of the arrow direction of FIG.

In order to obtain the maximum interference signal through the phase modulator 150, the area of the fixed reflecting mirror 151 and the area of the moving reflecting mirror 155 may have a ratio of 1: 1. However, the present invention is not limited thereto.

The phase of the signal reflected from the fixed mirror 151 is not modulated and the phase of the signal reflected by the fixed mirror 151 is shifted. A phase modulation can be generated only with respect to a signal reflected through the reflection mirror 155. That is, as the moving stage 157 is moved, the moving reflecting mirror 155 is moved to generate the phase difference of the wavefront of the signal reaching the moving reflecting mirror 155, so that the interference information of the interference signal can be obtained.

Meanwhile, the light source 130 of this embodiment is disposed between the phase modulator 150 and the second lens 145 to provide light toward the transparent thin film 115, as shown in FIG. At this time, the light from the light source 130 is provided toward the transparent thin film 115 and has a light irradiation range covering a scan region of a signal generated by the image sensor 120.

Accordingly, an interference signal due to a difference in optical path between the transparent thin film 115 and the fingerprint surface can be obtained by using the transparent thin film 115 to configure the interferometer in the image sensor 120, The signal can be Fourier transformed to obtain the optical interferometry tomographic information of the fingerprint surface.

At this time, the light source 130 irradiates the transparent thin film 115 with various types of light.

Referring to FIG. 2A, the light source 130 may include a plurality of diverging members 131 disposed along the periphery of the donut-shaped light source case to diverge light toward the transparent thin film 115. And a signal generated from the image sensor 120 through the hollow region of the light source may be provided to the transparent thin film 115. The transparent thin film 115 and the transparent thin film 115 are provided through the light provided from the light source 130 having such a configuration and a part of the phase modulated signal provided from the image sensor 120 through the phase modulator 150 to the transparent thin film 115 It is possible to acquire the interference signal due to the difference in optical path between the fingerprint surface and the optical interferometry tomographic information of the fingerprint 101. [

2B and FIG. 1, the light source 130b of the present embodiment may be disposed between the second lens 145 and the transparent thin film 115, And a diverging member 131a for providing light to the transparent thin film 115 covering an area of the transparent thin film 115 to which the signal reaches. In this case, the size of the light source 130 may be smaller than the size of FIG. 2A.

Referring to FIG. 2B and FIG. 1, the light source 130b of this embodiment may be arranged to have a triangular structure in the horizontal direction between the second lens 145 and the transparent thin film 115. A diverging member 131b for diverging light to each of the three light sources 130 is provided so that the light covering the region of the transparent thin film 115 to which the signal of the image sensor 120 reaches reaches the transparent thin film 115 can do.

However, the structures of the light sources 130, 130a, and 130b are not limited thereto, and it is natural that they may have different structures.

On the other hand, the transparent thin film 115 of the present embodiment is a portion directly contacting the fingerprint 101 of the measurement subject, as described above. This transparent thin film 115 may be provided by, for example, glass and a polymer-based thin film including acrylic, PMMA, polypropylene, PET, or the like. However, the material of the transparent thin film 115 is not limited thereto.

A signal from the image sensor 120 simultaneously receives light from the light source 130 in the transparent thin film 115 and obtains tomographic information about the fingerprint 101 by scanning the fingerprint 101 positioned in the transparent thin film 115 You can do it.

Next, the process of acquiring tomographic information by the fingerprint recognition apparatus 100 of the present embodiment is expressed as an equation.

The following equation 1 expresses an interference signal that can be obtained by changing the interference length in the interferometer, that is, by adjusting the degree of movement of the moving reflecting mirror 135. [

...식 1

... Equation 1

Here, p represents the path difference of the interferometer, and v is the wave number. The total interference signal obtained from the photodetector provided in the image sensor 120 (110) can be expressed by the following Equation (2).

...식 2

... Equation 2

From Equation (2), the following Equation (3) can be obtained through the Fourier transform, and as a result, intensity information in the wave number region can be acquired.

...식 3

... Equation 3

The obtained interference signal in the wavenumber region can be Fourier-transformed to obtain the optical interferometer tomographic image. The obtained interference signal can be expressed by the following Equation (4).

...식 4

... Equation 4

In Equation 4, I _s is the intensity of light according to the number of waves by the fingerprint 101 and the transparent thin film 115, and? X represents the difference in length between the fingerprint 101 and the transparent thin film 115. If the obtained interference signal is Fourier transformed, the following Equation 5 can be obtained.

...식 5

... Equation 5

Here, the delta function includes a sample, for example, tomographic information of the fingerprint 101. [

3, the phase modulation of a part of signals can be performed through the moving reflection mirror 155 of the phase modulator 150, and the interference fringe information obtained through the phase modulation, that is, It can be seen that spectral information, that is, intensity change according to wavelength can be obtained.

As described above, according to the embodiment of the present invention, a part of the signal generated from the image sensor 120 during the light emission from the light source 130 toward the transparent thin film 115 where the fingerprint 101 is positioned The optical interferometry tomographic information of the fingerprint 101 of the measurement subject can be obtained by acquiring the interference signal and performing Fourier transform on the interference signal.

Therefore, even if the external fingerprint layer of the fingerprint 101 of the person to be measured is damaged, the identification of the fingerprint layer can be accurately and reliably performed.

In addition, supersonic spectral images having spectral resolution and spectral bandwidth can be obtained through the Fourier transform without applying the same material as the dispersion medium, and slimming of the apparatus can be achieved.

Hereinafter, the optical interferometer tomography-based fingerprint recognition apparatus according to another embodiment of the present invention will be described, but the description of the substantially same components as those of the above-described embodiment will be omitted.

FIG. 4 is a schematic view illustrating an internal configuration of a conventional optical interferometer tomography-based fingerprint recognition device according to another embodiment of the present invention, and FIG. 5 is a diagram illustrating a state in which the device shown in FIG. 4 is applied to a smart device .

Referring to FIG. 4, the fingerprint recognition apparatus 200 according to another embodiment of the present invention differs from the fingerprint recognition apparatus 100 (see FIG. 1) and the phase modulator 250 of the above- have. The fingerprint recognition apparatus 200 of this embodiment also includes a case 210, an image sensor 220, a first lens 241, a phase modulator 250, a second lens 245, and a light source 230 . However, if the phase modulator 150 of the fingerprint recognition device 100 is a reflection type, there is a difference in that the phase modulator 250 of the present embodiment is of the transmission type.

4, the phase modulating unit 250 of the present embodiment includes a dummy transmissive element 255 for transmitting a part of a signal generated from the image sensor 220 and a dummy transmissive element 255 for transmitting another part of the signal, And a variable transmission element 251 for generating a phase difference by making a phase difference.

With this arrangement, a part of the signal is transmitted as it is, and another part of the signal can be modulated in phase by receiving an external signal and changing the effective refractive index of the signal when it is transmitted through the variable transmission element 251.

4, the variable transmission type element 251 is configured to change the effective refractive index of a signal according to an external signal provided from the signal application unit 254 provided in the transmission member and the transmission member adjacent to the dummy transmission type element 255, The refractive index changing member 257 may be provided.

The external signal applied to the refractive index changing member 257 may be any voltage, heat or pressure given from the external signal applying unit. The refractive index changing member 257 may be provided in the form of a film on the transmitting member as a liquid crystal or polymer-based electro-optical material.

Meanwhile, the light source 230 of the present embodiment may be disposed between the second lens 245 and the transparent thin film 15 to emit light to the transparent thin film 215. The light source 230 may be of the type shown in FIGS. 2A to 2C, but is not limited thereto.

As described above, in the present embodiment, the transmission type phase modulation is performed on a part of the signal generated from the image sensor 220 while the light is emitted from the light source 230 toward the transparent thin film 215 on which the fingerprint 201 is positioned The optical interferometry tomographic information of the fingerprint 201 of the measurement subject can be obtained by acquiring the interference signal and performing Fourier transform on the interference signal.

Meanwhile, the fingerprint recognition device 200 of the present embodiment may be provided in the smart device 10 as shown in FIG. For example, a module such as the fingerprint recognition device 200 of this embodiment is provided on one side of the device case of the smart device 10, so that the fingerprint 201 can be recognized using the smart device 10. In this case, since the fingerprint 201 can be recognized while carrying the smart device 10, the efficiency of the operation can be improved.

Hereinafter, the optical interferometer tomography-based fingerprint recognition apparatus according to another embodiment of the present invention will be described, but portions that are substantially the same as those of the above-described embodiments will not be described.

FIG. 6 is a schematic view illustrating an internal configuration of a conventional optical interferometric tomography-based fingerprint recognition apparatus according to another embodiment of the present invention. Referring to FIG.

As shown in the figure, the optical interferometer tomography-based fingerprint recognition apparatus 300 according to another embodiment of the present invention includes a case 310, The image sensor 320, the first lens, the reflection type phase modulator 350, the second lens, and the light source 330, but differs in the position of the light source 330. The light source 330 is embedded in one side of the case 310 adjacent to the image sensor 320 and emits light in a direction perpendicular to the signal irradiation direction of the image sensor 320. The light source 330 and the image sensor 320 The beams from the image sensor 320 and the light from the light source 330 can be coaxial with each other.

The light from the light source 330 reflected by the beam splitter 360 in the direction of the phase modulating unit 350 may be reflected vertically by the phase modulating unit 350 and directed to the transparent thin film 315, As shown, a signal from the image sensor 320 can provide light to the area of the transparent thin film 315 that it reaches.

Accordingly, the optical interferometer tomographic information of the fingerprint 301 of the measurement subject can be obtained by obtaining the interference signal by phase-modulating a part of the signal generated from the image sensor 320 while performing the optical interference, and by Fourier transforming the interference signal .

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Accordingly, such modifications or variations are intended to fall within the scope of the appended claims.

100: Optical interferometry tomography based fingerprint recognition device
110: Case
120: Image sensor
130: Light source
150: phase modulation unit

Claims (4)

A case in which a transparent thin film having an inner space and having a fingerprint of a subject to be measured is disposed on one side;
An image sensor disposed on the other side of the case and generating a signal for acquiring an ultrasound image of a measurement object;
A light source for providing light to an area of the transparent thin film to which the signal from the image sensor reaches, separately from the signal of the image sensor, the light source mounted in the inner space of the case or a wall of the case; And
Wherein a signal generated from the image sensor is provided on a path toward the transparent thin film to reflect a part of a signal generated from the image sensor and to modulate and reflect the phase of another part to obtain interference fringe information, part;
/ RTI >
Wherein the phase modulator comprises:
A fixed reflecting mirror that reflects a portion of the signal generated from the image sensor and has a fixed position;
A moving reflective mirror that reflects another portion of the signal generated from the image sensor; And
And a moving stage for moving the moving reflecting mirror relative to the fixed reflecting mirror in a direction perpendicular to the reflecting surface of the moving reflecting mirror,
Wherein movement of the moving reflective mirror generates a phase difference between a portion of the signal reflected by the fixed reflective mirror and another portion of the signal reflected by the moving reflective mirror. The method according to claim 1,
The light source includes:
A donut-shaped light source case; And
And a plurality of diverging members disposed along the periphery of the light source case and emitting light toward the transparent thin film,
Wherein a signal generated from the image sensor through a hollow region of the light source case is provided in the direction of the transparent thin film. The method according to claim 1,
Wherein the light source is biased to one side between the phase modulator and the transparent thin film to provide light to a region of the transparent thin film from which the signal from the image sensor arrives. The method according to claim 1,
Wherein the light source is arranged to have a polygonal structure in a horizontal direction between the phase modulator and the transparent thin film to provide light to an area of the transparent thin film from which the signal from the image sensor arrives. Device.

Images