JPH10293015A - Optical detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To positively detect a specimen with a simple configuration allowing the specimen to contact the outer surface side of an optical surface so that it can simultaneously contact a set of transparent thin-film electrodes and applying incidence light to the optical surface at an incidence angle so that total reflection conditions are met. SOLUTION: An application beam L1 of an LED 3 is applied to a total reflection surface 12A of a right-angled prism 12 so that total reflection conditions are met. At this time, the finger tip of the specimen with a fingerprint to be detected is allowed to contact the outer side of the total reflection surface 12A. As a result, application light L20 being reflected on the total reflection surface 12A is emitted from an emission surface 12C and an image on the total reflection surface 12A is formed at a focal point of the detection part of a CCD 6. It is photoelectrically converted to an electrical signal S1 by the CCD 6, and an image- processing part 17 creates a binary image of a fingerprint according to the intensity distribution of the reflection light L20 based on the electrical signal S1. Further, a fingerprint that is detected by the binary image is compared with the specific fingerprint pattern that has already been registered. On the other hand, a set of transparent thin-film electrodes 13 are provided at the outer-surface side of the total reflection surface 12A and an organism detection device judges whether one that contacts it is part of an organism or not according to the change in permitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Table of Contents] The present invention will be described in the following order.

BACKGROUND OF THE INVENTION Prior Art (FIGS. 3, 5 to 7) Problems to be Solved by the Invention (FIGS. 3, 8 and 9) Means for Solving the Problems Embodiments of the Invention (FIGS. 1 to 4) (1) First Embodiment (FIGS. 1 to 3) (1-1) Configuration of Fingerprint Detection Device (FIGS. 1 and 2) (1-2) Transparent Electrode (1- 3) Operation of First Embodiment (FIG. 3) (1-4) Effect of First Embodiment (2) Second Embodiment (FIGS. 3 and 4) (3) Other Embodiments Form Effect of the invention

[0003]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical detection apparatus, for example, processes an image of a human fingerprint on the basis of light reflected from the surface of a fingertip, and performs fingerprint collation based on a fingerprint image obtained thereby. It is suitable for application to an optical detection device used in such a case.

[0004]

2. Description of the Related Art Conventionally, there has been proposed a fingerprint detecting device 1 as shown in FIG. When a fingerprint is detected using the fingerprint detection device 1, as shown in FIG. 6, a fingertip F, which is a fingerprint detection target, is first brought into contact with the outer surface side of the total reflection surface 2A on the hypotenuse of the right-angle prism 2. In advance, the illumination light L1 emitted from a light source such as a light emitting diode (LED) 3 is incident on an incident surface 2B on one isosceles side of a right-angle prism 2 having a cross section of an isosceles triangle.
More incident. At this time, the illumination light L1 incident on the right-angle prism 2 is formed into parallel light by passing through the collimator lens 4, and is incident on the total reflection surface 2A at an angle satisfying the total reflection condition.

In fact, the fingerprint is detected by irradiating the illumination light L1 with the fingertip F in contact with the outer surface side of the total reflection surface 2A of the right-angle prism 2 so that the reflected light obtained on the total reflection surface 2A is reflected by the right-angle prism. 2 is taken out from the other exit surface 2C of the isosceles 2 as an outgoing light L2, and is passed through an imaging optical system 5 to be a CCD (Couple Charged Device) as a light detecting means.
6 and the like, and the reflected light L2 is converted to an electric signal corresponding to the intensity of the reflected light by photoelectric conversion and extracted. Then, fingerprint collation is performed by using a technique such as pattern matching based on a fingerprint image created in the image processing unit 7 based on the electric signal detected by the CCD 6.

In this case, the principle of fingerprint detection using reflected light uses the fact that the reflectance of the total reflection surface 2A depends on the medium at the interface. That is, the surface of the fingertip F and the right angle prism 2
Since the refractive index of the sweat coming out of the fingertip F is larger than that of air at the interface with the total reflection surface 2A, the total reflection condition at the interface of the incident light to satisfy the total reflection condition is broken. As a result, the reflection from the convex portion of the fingerprint FP is extremely small as compared with the fact that a large amount of light is reflected in the concave portion of the fingerprint FP that is not in contact with the outer surface side of the total reflection surface 2A. In the fingerprint detection, a difference occurs in the intensity of light reflected from the total reflection surface 2A between the convex portion contacting the outer surface side of the total reflection surface 2A and the concave portion not contacting the outer surface side of the total reflection surface 2A. I use.

The total reflection condition in this case is given by the following equation.

[0008]

(Equation 1)

When a light ray is directed toward the air from the inside of the prism at an angle equal to or greater than the incident angle θ _i represented by
This is a condition for all rays to be reflected at the interface. The incident angle θ _i at this time is called a critical angle. Here, the refractive index of _air is n _air , and the refractive index of optical glass, which is the material of the prism, is n _glass .

For example, BK7 is used as the material of the right-angle prism 2.
Is used, since the refractive index n _{glass of} BK7 is about 1.5, if the medium on the emission side is air, the critical angle is calculated to be 42.1 degrees from equation (1). As a result, all light incident on the total reflection surface 2A of the right-angle prism 2 at an incident angle of 42.1 degrees or more is reflected. In this case, since the reflectivity of the total reflection surface 2A depends on the medium at the interface, and when the medium on the emission side becomes sweat, the refractive index n _sweat of glycerin ester, which is a main component of _sweat, is about 1.4.

[0011]

(Equation 2)

It can be seen that the critical angle under the condition of total reflection is about 67 degrees. Here, the refractive index of _sweat is n _sweat , and the refractive index of optical glass, which is the material of the prism, is n _glass .

With this arrangement, the total reflection surface 2 must be at an incident angle larger than the critical angle when the medium on the exit side is air.
No total reflection will occur on A. According to such a detection principle, the signal output S1 read by one line 9A of the CCD 6 becomes as shown in FIG. 7, whereby the concave and convex portions of the fingerprint FP contacting the total reflection surface 2A can be identified. Can be.

[0014]

In the fingerprint detecting apparatus 1 using the above-described optical detecting means, for example, a rubber pseudo finger made of urethane or latex or a xerographic system is used. As a result, there is a problem that a fingerprint copied using a copying apparatus in which toner ink is raised and fixed is erroneously recognized as a real human fingerprint.

Therefore, when reading a fingerprint, in addition to reading the fingerprint using an optical detecting means, a living body detecting means for detecting whether or not the read one is actually a fingertip of a human being is used together. Is considered.

In this case, the living body detecting means determines whether or not the sample having the shape of the fingerprint is a fingertip of a human being, that is, a part of the living body, and determines whether the sample has a change in dielectric constant or resistance value from the sample. It has been considered that the detection of the electrical characteristics is effective.

As shown in FIG. 8A, when a transparent electrode 8 for detecting electric characteristics is provided on the total reflection surface 2A of the rectangular prism 2 which is a fingerprint reading surface, the transparent electrode 8 is formed. The amount of light due to total reflection between the portion and the portion without the transparent electrode does not change much. As a result, the CCD
As shown in FIG. 8B, the signal output S1 read by the switch 6 hardly changes between the area where the transparent electrode 8 is provided and the area where the transparent electrode 8 is not provided.

However, when the fingertip F is brought into contact with the total reflection surface 2A, there is a difference between the refractive index of the transparent electrode material and the refractive index of the prism material, and as shown in Comparative Example 1 in FIG. A marked change occurs in the reflectance of the convex portion of the fingerprint between the portion provided and the portion not provided. As a result,
As shown in FIGS. 9A and 9B, the signal output from the CCD 6 is the fingerprint F in the region where the transparent electrode 8 is not provided.
Fingerprint FP for the output level of the portion corresponding to the concave portion of P
The output level of the signal output S1 corresponding to the convex portion of the transparent electrode 8 (shown as 9D in the figure) is almost zero.
In a certain area, the output level (shown as 9E in the figure) of the signal output S1 corresponding to the convex portion of the fingerprint FP increases, and the amplitude of the signal output decreases. Therefore, for example, 2
At the time of the digitized signal processing, a reference value for binarization must be set for a small amplitude corresponding to the transparent electrode 8 side. Therefore, in the fingerprint detection device 1 provided with the transparent electrode, the fingerprint There is a problem that the effective sensitivity of detection is reduced.

The present invention has been made in view of the above points, and an object of the present invention is to propose an optical detection device capable of reliably detecting a sample with a simple configuration.

[0020]

According to the present invention, there is provided an optical component having an optical surface that reflects incident light or transmits light on a back surface, and includes an optical component that reflects incident light or an optical surface with respect to the optical surface. Polarizing means for converting reflected light into a predetermined direction, light detecting means for detecting reflected light from the optical surface, a set of transparent thin-film electrodes provided on the outer surface side of the optical surface of the optical component, and a set of An electrical measuring means for measuring electrical characteristics between the transparent thin-film electrodes, wherein the specimen is brought into contact with the outer surface side of the optical surface so as to simultaneously contact a pair of transparent thin-film electrodes, and a condition for total reflection with respect to the optical surface is provided. By irradiating incident light at an incident angle that satisfies the following condition, and turning the incident light or the reflected light reflected on the optical surface into polarized light in a predetermined direction by a polarizing means. Detect electrical properties Occasionally, it can be detected at the same level regardless of the region without a region where there is a transparent thin film electrode reflectivity of the reflected light from the optical surface to be detected simultaneously.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment (1-1) Configuration of Fingerprint Detecting Apparatus In FIG. 1 in which parts corresponding to those in FIG. After illuminating light L1 emitted from the LED 3 as a light source is converted into parallel light through a collimator lens 4, the parallel light passes through a polarizing plate 11 disposed at a predetermined position between the light source and the prism, and the transmitted light is converted into P-polarized light. From the incident surface 12B on one of the isosceles to the right-angle prism 12 having a cross section of an isosceles triangle, the light is incident on the total reflection surface 12A on the inclined surface of the right-angle prism 12 at an incident angle satisfying the total reflection condition.

In this case, the polarizing plate 11 is disposed such that the direction vector of the magnetic field of the transmitted light is in a direction perpendicular to the total reflection surface 12A, that is, in a direction perpendicular to the plane of the drawing.
Thereby, the illumination light L1 incident on the right-angle prism 12 can be converted into P-polarized light.

Incidentally, light is an electromagnetic wave, and is affected by the dielectric constant difference at the boundary surface during reflection and refraction.
(Parallel) polarized light is perpendicular to it (S (S
enkrecht (polarized light) in general. That is, when light is obliquely incident on the reflecting surface, the intensities of the P-polarized light and the S-polarized light are generally not equal, and the intensity difference at this time differs depending on the refractive index (or dielectric constant) of the surface material. Here, the incident surface is a surface including incident light and a perpendicular to the boundary surface.

At this time, the total reflection surface 12 of the right-angle prism 12
A sample having a fingerprint FP to be detected, a fingertip F, is brought into contact with the outer surface side of A. As a result, the fingerprint FP is included in the reflected light L20 of the illumination light L1 reflected on the total reflection surface 12A.
A difference in strength occurs according to the uneven shape of the substrate.

The reflected light L20 reflected on the total reflection surface 12A of the right-angle prism 12 is emitted from the other emission surface 12C on the other isosceles side of the right-angle prism 12, and is imaged on the total reflection surface 12A by the imaging optical system 5. Is imaged so as to be focused on the detection unit of the CCD 6.

The CCD 6 converts the reflected light L20 into an electric signal S1.
And sends it to the image processing unit 7. Image processing unit 7
Creates a binary image of the fingerprint FP according to the intensity distribution of the reflected light L20 based on the electric signal S1. Further, in the image processing section 7, the fingerprint F obtained by the image processing is obtained.
Using the binary image of P, the fingerprint FP detected by, for example, the pattern matching method is collated with a predetermined fingerprint pattern already registered.

On the other hand, as shown in FIG.
On the outer surface side of the total reflection surface 12A, the film thickness is substantially uniform (for example, 330 [nm]) in a region corresponding to a portion where the fingertip F contacts.
) (13A and 13A)
B) is provided in a non-connected state. Transparent electrode 1
Each of 3A and 13B is connected to a living body detection device (not shown) through a conductor 14. Here, for example, when the fingertip F of a person comes into contact with both transparent electrodes 13A and 13B at the same time, the dielectric constant (or resistance value) between the transparent electrodes 13A and 13B changes due to sweat or the like adhering to the surface of the fingertip F. I do. The living body detection device can detect the change in the dielectric constant and determine whether or not the one that has contacted the transparent electrodes 13A and 13B is a part of a living body such as a human fingertip F based on the detection result. It has been made like that.

(1-2) Transparent electrode The transparent electrode 13 formed on the total reflection surface 12A is a conductive thin film called an ITO film. First, for example, the surface of the rectangular prism 12 made of BK7 (borosilicate crown glass) is heated to 330 ° C., and tin (Sn) is added to indium oxide (In ₂ O ₃ ) by 5 to 10%. ] And oxygen can be used as a reactive gas to form a film by a vacuum deposition method.

In this embodiment, magnesium fluoride (MgF ₂ ) is further formed on the outer surface of the ITO film formed on the outer surface of the total reflection surface 12A of the prism by a vacuum evaporation method. In this case, the ITO film and the magnesium fluoride film are formed to have a thickness of, for example, 330 [nm] and 50 [nm], respectively. By thus covering the surface of the transparent electrode 13 formed by the ITO film with the protective film such as a harder magnesium fluoride film, it is possible to prevent moisture from entering the glass forming the prism. To prevent the specific chemical change (burn) of glass, which is the material of the prism, and improve the weather resistance.

Incidentally, BK selected as a material of the prism
7 is the most inexpensive optical glass, has excellent chemical properties, and is hard to be scratched because it is a hard material. Further, it has characteristics such as excellent transmittance with respect to light having a wavelength longer than 350 [nm].

(1-3) Operation of First Embodiment In the above configuration, when a fingerprint FP of a human fingertip F is detected, the fingertip F first contacts the outer surface of the total reflection surface 12A of the right-angle prism 12. Let it. Then, the polarizing plate 11 arranged so that the illumination light L1 emitted from the LED 3 is formed into parallel light through the collimator lens 4 and the transmitted light is converted into P-polarized light.
Through.

Next, the P-polarized illumination light L1 is incident on the total reflection surface 12A from the incident surface 12B of the right-angle prism 12 at an incident angle satisfying the total reflection condition.

In this case, when the fingertip F is not in contact with the outer surface of the total reflection surface 12A, the incident light L1 incident on the right-angle prism 12 is totally reflected in all regions of the total reflection surface 12A.

When the fingertip F is in contact with the outer surface of the total reflection surface 12A of the right-angle prism 12, the refractive index caused by sweat or the like at the interface between the convex portion of the fingertip F and the total reflection surface 12A changes to air. By being larger, the total reflection condition is broken, and the reflectance from the convex portion of the fingerprint FP becomes extremely small.

As a result, the intensity of the reflected light changes in accordance with the uneven shape of the fingerprint FP of the fingertip F. By detecting this with the CCD 6, a signal output corresponding to the uneven shape of the fingerprint FP can be obtained. it can.

Further, in this case, the randomly polarized illumination light L1 emitted from the LED 3 is P-polarized by the polarizing plate 11, whereby the illumination light L1 incident on the right-angle prism 12 is reflected and refracted. As a result, the S-polarized light component that has been strengthened is removed, so that the reflected light L20 at a certain level from the convex portion of the fingerprint FP that contacts the total reflection surface 12A in both the region where the transparent electrode 13 is provided and the region where the transparent electrode 13 is not provided. Strength can be obtained.

The reflected light L20 reflected on the outer surface side of the total reflection surface 12A of the right-angle prism 12 in this manner is extracted from the exit surface 12C of the right-angle prism 12, and is passed through the imaging optical system 5 to the detection unit of the CCD 6. Focused on. As a result, the fingerprint F in contact with the outer surface of the total reflection surface 12A
The P-polarized reflected light L20 including the information on the P unevenness can be sent to the CCD 6. Further, the electric signal S1 detected by the CCD 6 is sent to the image processing unit 7,
By performing the image processing, it is possible to obtain image information corresponding to the uneven shape of the fingerprint FP.

At this time, the transparent electrodes 13A and 13A
By detecting a change in the dielectric constant caused by the fingertip F contacting the contact 3B with a living body detection device (not shown), the contact with the total reflection surface 12A based on the detection result is that of a person. Can be determined.

Using the result detected by the living body detection device and the image information of the fingerprint FP detected by the image processing unit 7, the one having the fingerprint collation and the fingerprint FP is actually the fingertip of a person. Can be determined at the same time.

The fingerprint detecting apparatus 10 can be used as a switch discriminating means for controlling, for example, the opening and closing of a door based on the result of fingerprint collation by the fingerprint detecting apparatus 10.

In this case, as shown in Embodiment 1 of FIG. 3, in the first embodiment, the fingerprint F on the thin film portion provided with the transparent electrodes 13A and 13B of the total reflection surface 12A is provided.
The reflectivity of the concave and convex portions of P is 100% and
The reflectance of the concave and convex portions of the fingerprint FP in the non-thin film portion where the thin film is not provided is 100 [%] and 0.03 [%], respectively, which are almost the same in the thin film portion and the non-thin film. It can be confirmed that there is such a tendency of the reflectance.

Incidentally, an antireflection film may be formed on the entrance surface and the exit surface of the prism. Thereby, it is possible to prevent the incident light intensity and the reflected light intensity from decreasing. In this case, the coating of the total reflection surface 12A is not particularly required, but if foreign matter such as dust adheres to the reflection surface, the condition of total reflection may not be satisfied due to the influence of the refractive index, and light may leak out of the prism. . In this case, if a film having a large light absorption such as a metal is provided, the intensity of reflected light is reduced, but if a film made of a material having a very small light absorption such as a dielectric is provided, there is a film. The intensity of the light that is totally reflected in both the portion and the portion without the film does not change. Therefore, the reflecting surface may be coated with a film having a very small absorption such as a dielectric.

(1-4) Effects of the First Embodiment According to the above configuration, the illumination light L1 incident on the total reflection surface 12A is converted into P-polarized light by the polarizing plate 11, so that the fingerprint can be obtained. By removing the S-polarized light component from the reflected light L20 of the convex portion of the FP, the reflectance of the convex portion of the sample that comes into contact with the total reflection surface 12A can be set to the same level in the region where the transparent electrode 13 exists and the region where the transparent electrode 13 does not exist. As a result, the output amplitude of the electric signal S1 output from the CCD 6 can be made sufficiently large, and thus the effective sensitivity at the time of the binary signal processing in the image processing section 7 can be improved to facilitate fingerprint detection.

(2) Second Embodiment In FIG. 4, reference numeral 20 denotes a fingerprint detection device according to a second embodiment, in which there is no polarizing plate between the light source and the entrance surface 12B of the prism. The configuration is the same as that of the first embodiment except that a polarizing plate 21 is provided so that the light L20 reflected from the total reflection surface 12A of the prism is converted into P-polarized light.

That is, the illumination light L1 emitted from the light source 3
Is totally reflected by the total reflection surface 12A of the right-angle prism 12, is emitted from the emission surface 12B, is converted into P-polarized light by the polarizing plate 21, and is focused on the CCD 6 through the imaging optical system 5. That is, the polarizing plate 21 is disposed such that the direction vector of the magnetic field of the reflected light L20 from the total reflection surface 12A is oriented in a direction perpendicular to the plane of the drawing. Thereby, the total reflection surface 1
The reflected light L20 from which the S-polarized component has been removed is obtained from 2A. Thus, in the CCD 6, the reflected light intensity obtained when the fingertip F is brought into contact with the total reflection surface 12A is compared with the portion having the transparent electrodes 13A and 13B. Detection can be performed at a constant intensity regardless of the portion not present.

In this case, as shown in the second embodiment in FIG. 3, the concave portion of the fingerprint FP in the thin film portion provided with the transparent electrodes 13A and 13B of the total reflection surface 12A, as in the first embodiment, The reflectance of the convex part is 100 [%] and 0.07, respectively.
[%], And the reflectance of the concave and convex portions of the fingerprint FP in the non-thin film portion where no thin film is provided is 10%, respectively.
At 0 [%] and 0.03 [%], it can be confirmed that the thin film portion and the non-thin film have almost the same tendency of reflectance.

According to the above arrangement, the reflected light L20 from the total reflection surface 12A is converted into P-polarized light by the polarizing plate 21, so that the S-polarized light component is removed from the reflected light L20 of the convex portion of the sample, and the convex portion is formed. Can be set to the same level in the region where the transparent electrode 13 exists and the region where the transparent electrode 13 does not exist. Thereby, the same effect as that of the above-described first embodiment can be obtained.

(3) Other Embodiments In the above-described embodiment, a case has been described in which a polarizing plate is used to extract a P-polarized component from the illumination light L1, but the present invention is not limited to this. For example, the illumination light L1 emitted from the light source light using a semiconductor laser device may be configured such that the polarization plane of the illumination light L1 is P-polarized with respect to the incidence of the prism.
May be set to be incident on the total reflection surface. In this case, since the laser light emitted from the semiconductor laser device is highly polarized at the time of emission, a P-polarized component can be obtained without using a polarizing plate, and thus the polarization direction of the illumination light L1 can be uniquely determined. By making the selection, even when the fingertip F is in contact with the total reflection surface provided with the transparent electrode, a substantially constant reflectance can be obtained regardless of each region on the total reflection surface having a different refractive index. The same effects as those of the first and second embodiments can be obtained.

Incidentally, as shown in Comparative Example 2 of FIG. 3, the illumination light irradiated from the semiconductor laser device disposed so that the polarization of the incident light with respect to the prism is S-polarized light is applied to the thin film portion of the total reflection surface 12A of the prism. When the light is incident on the non-thin film portion and the total reflection surface 12A is irradiated with S-polarized light, the reflectance of the contact portion of the convex portion of the fingertip F is 15.8% and 1.61% in the thin film portion and the non-thin film, respectively. ], It can be easily confirmed that the reflectance of the convex portion of the fingerprint FP is further higher than that of Comparative Example 1.

In the above-described embodiment, the case where the light source is the LED 3 or the semiconductor laser device has been described. However, the present invention is not limited to this, and the light source may be sunlight or an incandescent lamp. In this case, the same effect as in the above embodiment can be obtained by irradiating the illumination light with a predetermined wavelength using a filter or the like.

In the above embodiment, the case where the right-angle prism 12 is used as the optical element for totally reflecting the illumination light L1 has been described. However, the present invention is not limited to this.
As long as the condition for totally reflecting the incident light is satisfied, another prism may be used, whereby the same effect as in the above-described embodiment can be obtained.

In the above embodiment, the case where BK7 is used as the material of the prism has been described.
The present invention is not limited to this, and any optical glass or plastic material may be used. Further, even when the material of the prism is plastic, if the surface is coated with an ITO film, a silicon dioxide film or the like, the same effect as in the above-described embodiment can be obtained.

In the above-described embodiment, the case where the optical component to be brought into contact with the specimen is a prism has been described. However, the present invention is not limited to this. For example, a fiber optic plate (FOP) may be used. May be used. In this case, the end face obtained by obliquely cutting the body of the FOP is used as an optical surface, and incident light is made to enter the end face from the side face of the FOP so as to satisfy the total reflection condition, and the reflected light is directly transmitted from the end of the FOP to the CCD. To be incident.

Further, it is sufficient that a sufficient amount of light for light detection can be taken out without making incident light incident on the optical surface so as to satisfy the condition of total reflection.

In the above embodiment, the case where the polarizing plate 11 or 21 is used as the polarizing element has been described. However, the present invention is not limited to this, and a polarizing beam splitter or the like may be used.

In the above-described embodiment, the case where the ITO film is used as the transparent electrode 13 has been described.
The present invention is not limited to this, and any transparent thin film electrode may be used.

Further, in the above-described embodiment, a case has been described in which a configuration using a set of transparent electrodes 13A and 13B is used. However, the present invention is not limited to this, and for example, a bridge using four terminals is used. The dielectric constant or the resistance value may be measured.

Further, in the above-described embodiment, a case has been described where the fingerprint FP of the human fingertip F is used as a detection target by the fingerprint detection device. However, the present invention is not limited to this. The fingerprint FP is not limited to the fingertip F, and may be a fingerprint FP of the foot. The fingerprint FP is not limited to the fingerprint FP of a person and can be widely applied to animals in general. The object to be detected is not limited to the fingerprint FP, but may be a part of a living body having an irregular shape having a constant irregular shape such that a predetermined intensity change is generated in reflected light by contact with the total reflection surface of the prism. What is necessary is just to have.

[0060]

As described above, according to the present invention, it is possible to detect the electrical characteristics of a specimen that is in contact with the outer surface of the optical surface of an optical component, and at the same time, detect the incident light on the optical surface or the light incident on the optical surface. By making the reflected light at a predetermined polarization in the predetermined direction, the intensity of the reflected light on the optical surface can be made the same level in both the region where the transparent thin-film electrode is provided and the region where the transparent thin-film electrode is not provided. It is possible to realize an optical detection device that can easily detect reflected light including information on a specimen to be analyzed.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a first embodiment of a detection device according to the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of a prism provided with a transparent electrode.

FIG. 3 is a schematic block diagram showing a detection device according to a second embodiment of the present invention.

FIG. 4 is a schematic block diagram showing a conventional fingerprint detection device.

FIG. 5 is a schematic diagram for explaining the reading of a fingerprint using total reflection in a prism.

FIG. 6 is a schematic diagram and a signal waveform diagram for explaining a signal output detected from a fingerprint.

7A and 7B are a schematic diagram (FIG. 7A) and a signal waveform diagram (FIG. 7B) for explaining a signal output by reflected light of a prism provided with a transparent electrode.

FIG. 8 is a schematic diagram for explaining the reflectance detected by the fingerprint detection device.

9A and 9B are a schematic diagram (FIG. 9A) and a signal waveform diagram (FIG. 9B) for explaining a signal output detected from a fingerprint.

[Explanation of symbols]

1, 10, 20 ... fingerprint detection device, 2, 12 ... right angle prism, 3 ... LED, 4 ... collimator lens, 5 ...
... imaging optical system, 6 ... CCD, 7 ... image processing unit, 8,
13A, 13B ... transparent electrode, 11, 21 ... polarizing element.

Claims (6)

[Claims] 1. An optical component having an optical surface that reflects incident light or transmits through a back surface, and polarizing means that converts the incident light to the optical surface or the reflected light reflected by the optical surface into polarized light in a predetermined direction. Light detection means for detecting light reflected from the optical surface; a pair of transparent thin-film electrodes provided on the outer surface side of the optical surface of the optical component; and electrical characteristics between the pair of transparent thin-film electrodes. And an electrical measuring means for measuring the sample, and the sample is brought into contact with the outer surface side of the optical surface so as to simultaneously contact the set of transparent thin-film electrodes, and the incident angle satisfying the condition of total reflection with respect to the optical surface. And irradiating the incident light. 2. The polarizing means according to claim 1, wherein said polarizing means comprises a polarizing element for making at least one of said light incident on said optical surface or said reflected light on said optical surface P-polarized. Optical detection device. 3. The optical system according to claim 1, wherein the polarizing means converts the incident light on the optical surface into P light on the optical surface.
2. The optical detection device according to claim 1, further comprising a semiconductor laser device arranged to be polarized. 4. The optical detecting apparatus according to claim 1, wherein said electric measuring means is an electric measuring means for measuring a dielectric constant or a resistance value of said sample between said pair of transparent thin film electrodes. . 5. The optical detection device according to claim 1, wherein the transparent thin-film electrode has a hard thin film covering an outer surface of the transparent thin-film electrode. 6. The optical detection device according to claim 1, wherein the optical surface is disposed so as to totally reflect the incident light.