JP7015023B2 - Terahertz wave half mirror and irradiation device using the half mirror - Google Patents

Description

The present invention relates to a terahertz wave half mirror for irradiating a terahertz wave and an irradiation device using the half mirror.

In recent years, various detection devices using terahertz waves have been proposed. For example, Patent Document 1 below proposes an inspection device for inspecting foreign matter adhering to inspected items such as banknotes in a non-contact manner at high speed and with high efficiency.

In this inspection device, the terahertz wave from the oscillator is mechanically changed in angle by a mirror such as a galvano mirror to irradiate the entire inspected object such as banknotes, or the irradiated part of the inspected object is in a plurality of areas. By arranging an oscillator in each area and irradiating it, the entire object to be inspected such as banknotes was irradiated.

According to such an inspection device, a terahertz wave can be applied to the entire inspected object such as a banknote for inspection, and a foreign substance such as a tape attached to the inspected item such as a banknote can be inspected at high speed without contact. Moreover, it is possible to detect with high efficiency.

Japanese Unexamined Patent Publication No. 2016-80452

However, in the terahertz wave irradiation device provided in the conventional inspection device, in the case of a device that irradiates the entire object to be inspected such as banknotes by mechanically changing the angle of the mirror, the change in the angle of the mirror causes the banknotes and the like. Since the entire length of the object to be inspected is irradiated, it is necessary to provide a long distance from the mirror to the item to be inspected such as banknotes, and the device tends to be large. In addition, it is not easy to stably maintain the precise and high-speed operation of the mirror due to vibration and wear.

Furthermore, when the irradiated area is divided into a plurality of areas and an oscillator is placed in each area to irradiate, although it is resistant to vibration, it is controlled by providing oscillators, lenses, etc. for the number of areas where the irradiated area is divided. There is also a problem that the device configuration tends to be complicated and expensive.

Therefore, the first object of the present invention is to provide a terahertz wave half mirror that can be easily miniaturized and can stably irradiate a terahertz wave for a long period of time with a simple configuration, and irradiation of the terahertz wave using the half mirror. The second purpose is to provide the device.

The terahertz wave half mirror of the present invention that achieves the first object is made of a silicon wafer, and the transmittance or reflectance for the terahertz wave incident on the silicon wafer is set by the carrier density of the silicon wafer. Configure.

In the terahertz wave half mirror of the present invention, the transmittance may be set by the thickness of the silicon wafer.

The terahertz wave irradiation device of the present invention that achieves the second object described above includes a terahertz wave oscillator, a confining component that uses the terahertz wave as a predetermined luminous flux, and a plurality of transmissing and reflecting or reflecting terahertz waves. A half mirror is provided, and a plurality of half mirrors are arranged in a matrix at predetermined locations, and a light flux is incident from the upper side or the lateral side of one end or the other end of a row of the plurality of half mirrors, and the plurality of half mirrors are provided. The terahertz wave was configured to be emitted in a line from the lower end side of the row by the transmission and reflection in.

In the terahertz wave irradiation device of the present invention, the transmittance or reflectance of a plurality of half mirrors may be set so that the terahertz waves emitted in a line form have a predetermined output distribution. The half mirror can be configured from a silicon wafer. A plurality of half mirrors may be combined with silicon wafers having different carrier densities. A plurality of half mirrors may be combined with silicon wafers having different thicknesses.

A holding portion for holding each half mirror of a plurality of half mirrors at a predetermined angle may be provided.
An irradiation device case for accommodating the holding portion may be provided, and the oscillator may be connected to the irradiation device case.

According to the present invention, a terahertz wave half mirror is composed of a silicon wafer, and the transmittance or reflectance for the terahertz wave incident on the silicon wafer can be easily set by adjusting the carrier density of the silicon wafer. Can be done. Therefore, it is possible to provide a half mirror suitable for terahertz waves, which is easy to miniaturize and has a simple configuration.

According to the present invention, the terahertz wave irradiation device is configured to include a plurality of half mirrors, and a predetermined light flux of the terahertz wave is incident on one of the half mirrors, so that a large number of oscillators are not used. , It is possible to provide an irradiation device capable of irradiating a terahertz wave having a predetermined output distribution in a line shape. Therefore, the configuration of the irradiation device can be simplified, it is not easily affected by vibration and the usage environment, and terahertz waves can be stably irradiated for a long period of time.

It is a figure explaining the operation of the half mirror which concerns on 1st Embodiment of this invention, (a) is the schematic sectional view which shows the transmitted wave and the reflected wave, (b) is the schematic sectional view which explains the transmitted wave, (c). ) Is a graph explaining the intensity of the transmitted wave. It is a block diagram which shows the apparatus which measures the transmittance and the reflectance of a half mirror with a terahertz wave. An inspection device using a terahertz wave irradiation device according to a second embodiment of the present invention will be described, where (a) is a front view and (b) is a right side view. It is a figure which shows the configuration example 1 of a plurality of half mirrors at 60 GHz. It is a figure which shows the configuration example 2 of a plurality of half mirrors at 60 GHz. It is a figure which shows the configuration example 1 of a plurality of half mirrors at 90 GHz. It is a figure which shows the configuration example 2 of a plurality of half mirrors at 90 GHz. It is a figure which shows the configuration example 1 of a plurality of half mirrors at 140 GHz. It is a figure which shows the configuration example 2 of a plurality of half mirrors at 140 GHz. It is a figure which shows the configuration example 3 of a plurality of half mirrors at 140 GHz. It is a schematic plan view of the terahertz wave irradiation apparatus of Example 2. It is a figure which shows the output distribution of the terahertz wave in the X direction of the terahertz wave irradiation apparatus of Example 2. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the scope of the present invention is not limited to the embodiments and can be appropriately changed. In particular, the shape, dimensions, positional relationship, etc. of each member described in the drawings merely indicate conceptual matters, and can be arbitrarily changed according to the application situation. In each figure, the same or corresponding members and the like are designated by the same reference numerals.

[First Embodiment]
In the first embodiment, a half mirror used for a terahertz wave irradiation device will be described.
1A and 1B are views for explaining the operation of the half mirror 1 according to the first embodiment of the present invention, in which FIG. 1A is a schematic cross-sectional view showing a transmitted wave 3 and a reflected wave 4, and FIG. 1B is a transmitted wave 3. The schematic cross-sectional view to be described, (c) is a graph explaining the intensity of the transmitted wave 3.
As shown in FIG. 1A, when the terahertz wave 2a irradiated from the oscillator 2 is incident on the half mirror 1, a terahertz wave transmitted through the half mirror 1 and a terahertz wave reflected on the surface of the half mirror 1 are generated. The terahertz wave transmitted through the half mirror 1 is the transmitted wave 3, and the terahertz wave reflected on the surface of the half mirror 1 is the reflected wave 4. When the intensity of the incident terahertz wave is 100, the transmittance in which the intensity of the transmitted wave 3 is expressed in% and the reflectance in which the intensity of the reflected wave 4 is expressed in% with respect to the incident wave are used for the half mirror 1. It can be adjusted with the material.

As the material used for the half mirror 1, a semiconductor such as silicon (Si) or germanium (Ge) having the properties of an insulator and a conductor can be preferably used. As the half mirror 1, a silicon wafer having high crystallinity and low cost can be preferably used. In the following description, the half mirror 1 will be described as a silicon wafer found to exhibit good characteristics in a terahertz wave in Example 1 described later.

The silicon wafer 1 can have a thickness of about 0.1 mm to 2 mm from the measurement results of the transmittance and the reflectance in the terahertz wave described later and the ease of handling thereof.

It was found that if the carrier density of the silicon wafer is low, for example, if the value is about 1 × 10 ¹² cm ^-3 , the half mirror 1 can obtain the transmitted wave 3 and the reflected wave 4 at the same time.

As shown in FIG. 1 (b), when a terahertz wave is incident on the half mirror 1, the intensity of the transmitted wave 3 is expressed by the following equation (1).
I = I ₀ × exp (-αx) (1)
Here, I ₀ is the incident light intensity of the terahertz wave on the surface, that is, when x = 0 in the x direction perpendicular to the thickness direction of the silicon wafer. α is the absorption coefficient of the terahertz wave (cm ^-1 ), and the intensity of the terahertz wave is the reciprocal of the distance at which the intensity of the terahertz wave on the surface of the silicon wafer decays from I ₀ to 1 / eI ₀ , that is, about 0.37I ₀ . be.

The thickness of a silicon wafer having a transmittance of about 37% is approximately 1 / α. By calculating the transmittance of the silicon wafer in the thickness direction (x direction) based on this α by the equation (1), the transmittance of the silicon wafer at a predetermined thickness can be calculated (FIG. 1 (c). )reference).

FIG. 1C is a calculation example of exp (−αx), and the thickness for obtaining a predetermined transmittance can be calculated based on this calculation. Even if the transmittance is not necessarily about 37%, when a predetermined value is obtained, the value of x corresponding to the transmittance is obtained from FIG. 1 (c), and the predetermined transmittance is obtained from the value. The thickness of may be calculated. Thereby, when silicon wafers having the same carrier density are used, the transmittance can be adjusted by the thickness thereof.

On the other hand, if the carrier density of the silicon wafer is, for example, about 1 × 10 ¹⁶ cm ^-3 or more, the conductivity of the surface of the silicon wafer is improved, so that the half mirror 1 in which only the reflected wave 4 is generated is obtained. The reflectance of a silicon wafer can be controlled by its carrier density, and the reflectance can be increased by increasing the carrier density. The half mirror 1 of the present invention is made of, for example, a silicon wafer, and unlike metal, it is difficult to obtain 100% reflection. As will be described later, reflection occurs simultaneously without transmitting terahertz waves, that is, absorption and 100% or less. Reflections occur. In the present specification, when such absorption and reflection of terahertz waves occur at the same time, it is referred to as a half mirror in which reflection occurs.

(Measurement of transmittance and reflectance)
The transmitted wave 3 and the reflected wave 4 of the silicon wafer change depending on the thickness and carrier density of the silicon wafer, and further change with the frequency of the terahertz wave incident on the silicon wafer. Therefore, it is desirable to actually measure and obtain the accurate transmittance and reflectance of the silicon wafer for the terahertz wave at the frequency of the terahertz wave to be used.

FIG. 2 is a block diagram showing a device 9 for measuring the transmittance and reflectance of the half mirror 1 with a terahertz wave. As shown in FIG. 2, the terahertz wave transmittance and reflectance measuring device 9 includes an oscillator 2 that irradiates the half mirror 1 with the terahertz wave, and a detector that detects the transmitted wave 3 of the terahertz wave transmitted through the half mirror 1. 5 and a detector 6 for detecting the reflected wave 4 of the terahertz wave reflected by the half mirror 1 are included.

As a terahertz wave condensing component 7, for example, a parabolic mirror may be arranged between the oscillator 2 and the half mirror 1. Further, for example, a lens may be arranged as a condensing component 8 between the half mirror 1 and the detector 5 of the transmitted wave 3 and between the half mirror 1 and the detector 6 of the reflected wave 4. As the material of the lens, a fluororesin such as Teflon (registered trademark) can be used.

According to the transmittance and reflectance measuring device 9 shown in FIG. 2, the light collecting component has a light intensity of a terahertz wave of a predetermined frequency incident on the half mirror 1 from the oscillator 2 via the light collecting component 7. The transmittance and reflectance can be measured by the intensities of the transmitted wave 3 and the reflected wave 4 measured by the detector 5 and the detector 6 via 8. The frequency of the terahertz wave is, for example, 60 GHz, 90 GHz, 140 GHz and the like.

[Second Embodiment]
As a second embodiment, a terahertz wave irradiation device will be described.
In the second embodiment of the present invention, an example in which a terahertz wave irradiation device using the half mirror 1 of the first embodiment is incorporated in an inspection device will be described. As an example of the use of this inspection device, it is applied to a device for inspecting whether or not foreign matter such as transparent tape is attached to the front surface or the back surface of paper sheets as shown below.

3A and 3B are views for explaining an inspection device 10 using the terahertz wave irradiation device 20 according to the second embodiment of the present invention, where FIG. 3A is a front view and FIG. 3B is a right side view. As shown in FIGS. 3A and 3B, the inspection device 10 has one surface of a transport device 12 for transporting the paper leaves 11 to be inspected and a paper leaf 11 transported by the transport device 12. An irradiation device 20 that irradiates a terahertz wave from the side and a detection device 30 that detects a transmitted wave on the other surface side of the paper sheet 11 are provided.

The paper leaves 11 to be irradiated with the terahertz wave are rectangular banknotes and the like, and the entire surface of one surface is the irradiated portion.
The transport device 12 transports the paper leaves 11 in the direction along the surface, and the transport guides 13 are placed on the upper and lower portions of the paper leaves 11 so as to pass the terahertz wave irradiation position 12a in the lateral direction or the longitudinal direction. It has a structure in which 13 is arranged. Resin or glass can be used as the members of the transport guides 13 and 13.

The irradiation device 20 includes an oscillator 21, a condensing component 22, and a plurality of half mirrors 23. The terahertz wave from the oscillator 21 is used as a line light source by the plurality of half mirrors 23, and the irradiation position of the transfer device 12 is provided. The paper leaves 11 are irradiated with 12a. Further, it is desirable to provide the condensing component 22 and irradiate the half mirror 23 with the terahertz wave from the oscillator 21 as a predetermined luminous flux.

The oscillator 21 has an oscillating element such as a gunn diode, an IMPATT diode, various diodes such as a tannet diode, a semiconductor such as Si, and a transistor formed from a compound semiconductor such as SiGe, GaAs, and InP. , 30 GHz (GHz is 109 Hz) to ¹² THz can emit terahertz waves. The oscillator 21 is preferably installed in the form of a metal plate having excellent thermal conductivity, such as a copper plate or an aluminum plate. By further thermally connecting the metal plate to a metal member such as a housing, the heat dissipation area can be expanded and the heat dissipation effect can be improved. For example, the irradiation device 20 may include a case for the irradiation device, and the oscillator 21 may be connected to the case for the irradiation device.

In the irradiation device 20 shown in FIG. 3A, the cross section of the arrangement of the plurality of half mirrors 23 is shown in a model manner. The plurality of half mirrors 23 are composed of first to seventh half mirrors 23 _a to 23 _g arranged at the seven positions in a matrix arrangement of 5 columns and 3 rows. As shown in FIG. 3A, the columns are arranged in the X direction and the leftmost column is one column, and the rows are arranged in the Z direction and the upper side is one row. In the case of illustration, each of the plurality of half mirrors 23 is arranged so that a terahertz wave is incident on the surface thereof at an angle of 45 °. However, the angle may be finely adjusted in order to make the distribution of the intensity of the emitted light from each half mirror, that is, the output distribution, which will be described later, uniform.

The terahertz wave emitted from the oscillator 21 is focused by a focusing component 22 such as a parabolic mirror, and is incident on the first half mirror 23a in a row and a row. As shown in the figure, the antenna 21a may be connected to the oscillator 21. The antenna 21a is, for example, a horn antenna. The terahertz wave having a predetermined luminous flux by the light collecting component 22 passes through the first half mirror 23a and the second half mirror _23b downward (Z direction) on the paper surface, and is the first on the leftmost side of the paper surface. The emitted light is 26 _a . In the plurality of half mirrors 23, one end or the other end of the first row of the matrix is preferably the half mirror into which the terahertz wave initially made into a predetermined luminous flux is incident from the oscillator 21, and as shown in the figure, one row and one row. It can be incident from above the half mirror. Further, the incident may be made from the side instead of the upper side.

The terahertz wave reflected to the right of the paper surface by the first half mirror 23 _a is reflected by the third half mirror 23 _c and reflected in the Z direction, and is transmitted through the fourth half mirror 23 _d in the Z direction. It is the second second emitted light 26 _b from the left side of the paper.

The terahertz wave reflected to the right of the paper surface by the second half mirror 23 _b is reflected in the Z direction by the fifth half mirror 23 _e to become the third emitted light 26 _c from the left side of the paper surface.

The terahertz wave reflected to the right of the paper surface by the fourth half mirror 23 _d is reflected in the Z direction by the sixth half mirror 23 _f to become the fourth emitted light 26 _d from the left side of the paper surface.

The terahertz wave transmitted to the right of the paper surface by the third half mirror 23 _c is reflected in the Z direction by the seventh half mirror 23 _g to become the fifth emitted light 26e from the left side of the paper surface.

As a result, the terahertz wave of a predetermined luminous flux incident on one end or the other end of the first row of the matrix in which the plurality of half mirrors 23 are arranged is generated on the lower end side of each column, that is, the emission portion shown in FIG. 3 (a). The first to fifth emission lights 26 _a to 26 _e are emitted from 25.

An example of how to assemble the irradiation device 20 will be described.
First, a method of manufacturing a plurality of half mirrors 23 will be described.
A plurality of silicon wafers are prepared according to the configuration of the plurality of half mirrors 23 at a predetermined terahertz wave frequency described later. It is preferable that the shape of the plurality of silicon wafers is, for example, a circular shape, a quadrangular shape, or a rectangular shape. A holder made of resin, for example, has a groove or the like that can arrange a plurality of silicon wafers at predetermined positions and serves as a holding portion for the silicon wafers. The resin holder may be configured to include a holding portion for holding each half mirror of the plurality of half mirrors 23 at a predetermined angle.
Next, a rectangular silicon wafer is inserted into the holding portion of the holder and fixed with an adhesive or the like. As a result, each half mirror constituting the plurality of half mirrors 23 is fixed to the holding portion held at a predetermined angle.
Next, the plurality of half mirrors 23 held in the holder are adjusted together with the oscillator 21 and the condensing component 22 so as to have a predetermined optical arrangement, and then fixed to the irradiation device case with an adhesive, a screw, or the like. , The irradiation device 20 can be manufactured.

According to the terahertz wave irradiation device 20 according to the second embodiment of the present invention, a plurality of half mirrors 23 are arranged at predetermined positions in a matrix, and a light flux is directed to one end or the other end of a row of the plurality of half mirrors 23. It is incident from the upper side of the row, and the terahertz wave is emitted in a line from the lower end side of the row due to transmission and reflection in the plurality of half mirrors 23. Further, a predetermined output distribution can be obtained by setting the transmittance or the reflectance of the plurality of half mirrors 23. The predetermined output distribution is, for example, a line-shaped uniform output distribution or a concave or convex output distribution, and may be appropriately selected according to the purpose of the irradiation device 20.

That is, the terahertz wave incident from the oscillator 21 becomes a transmitted wave 3 or a reflected wave 4 by the plurality of half mirrors 23 _a to 23 _g , and the transmitted or reflected terahertz wave is further reflected or transmitted by the other half mirror 23. Through the optical path as described above, the first to fifth emitted lights _26a to _26e are linear. For example, it is a line light source in a direction perpendicular to the transport direction of the paper sheets 11. As a result, as shown in FIG. 3B, the line-shaped terahertz wave from the irradiation device 20 is irradiated to the paper leaves 11 at a predetermined angle rather than vertically, and the paper leaves 11 are irradiated. The transmitted terahertz wave is incident on the detection device 30.

The detection device 30 for detecting the transmitted wave on the other surface side of the paper sheet 11 is, for example, an irradiation device via a light-condensing optical component 31 including a frenell lens, a convex lens, a concave lens, and the like, and a light-condensing optical component 31. A large number of detection element groups 33 composed of shotkey barrier diodes 32a to 32n and the like arranged linearly so as to face the emission unit 25 of 20 and the detection results of the detection element group 33 together with the transfer information of the transfer device 12. It has an information processing unit 34 that determines the presence / absence and position of foreign matter by processing. The Schottky barrier diodes 32a to 32n are mounted on, for example, the printed circuit board 35.

The information processing unit 34 has a two-dimensional intensity distribution of the transmitted wave when the paper leaf 11 having no foreign matter adhered to the paper leaf 11 and a transmission when the paper leaf 11 having foreign matter adhered to the paper leaf 11 are detected. It is configured to detect whether or not foreign matter is attached by comparing it with the two-dimensional intensity distribution of the wave.

In this inspection device 10, when the paper leaves 11 are transported by the transport device 12, they move in the lateral direction or the longitudinal direction with the front surface or the back surface facing the irradiation device 20 side and pass through the irradiation position 12a. .. The irradiation position 12a is irradiated with a line-shaped terahertz wave from the irradiation device 20 so as to cross the paper sheets 11 in the longitudinal direction or the lateral direction. When the paper leaves 11 pass through the irradiation position 12a, the line-shaped terahertz waves crossing the longitudinal direction or the lateral direction move relative to each other in the lateral direction or the longitudinal direction in order to irradiate the entire surface of the paper leaves 11. .. At the irradiation position 12a, the terahertz wave transmitted through the paper leaves 11 is detected by the detection device 30, and the information processing unit 34 detects whether or not foreign matter is attached to the paper leaves 11.

According to the terahertz wave irradiation device 20 according to the second embodiment of the present invention, the light emitted from the emitting unit 25, that is, the light 26, that is, due to the transmission and reflection of the plurality of half mirrors 23 arranged inside the irradiation device 20. , The first to fifth emission lights 26 _a to 26 _e are emitted. Therefore, by arranging the emitting unit 25 close to the paper leaves 11, the terahertz waves can be easily applied to the paper leaves 11 in a line shape.

According to the terahertz wave irradiation device 20, since the line-shaped terahertz wave can be irradiated to the paper sheets 11 by one oscillator 21, it is not necessary to use a large number of oscillators or a combination of one oscillator 21 and a scanning element. As a result, the irradiation device 20 can be significantly miniaturized.

Further, there is no need for a scanning element to irradiate the entire length of the paper sheets 11, and no drive mechanism or anti-vibration mechanism is required. Moreover, since the irradiation device 20 can form a line light source by a plurality of half mirrors 23, the configuration can be simplified. Therefore, it is not easily affected by vibration and the usage environment, and can stably irradiate terahertz waves for a long period of time.

(Example of half mirror configuration)
Next, a configuration example of a plurality of half mirrors 23 of the terahertz wave irradiation device 20 at 60 GHz, 90 GHz, and 140 GHz will be described.
Specific physical property values such as the thickness, carrier density, transmittance and reflectance of the silicon wafer used in the configuration of the half mirror 23 below are based on the data acquired by the measurement in Example 1 described later. .. Further, as the output distribution, a configuration example is shown in which a uniform output distribution in a line shape or a substantially concave output distribution can be obtained.

(60 GHz configuration example 1)
FIG. 4 is a diagram showing configuration example 1 of a plurality of half mirrors at 60 GHz. The plurality of half mirrors 23 are arranged in a first half mirror 23 ₁ arranged in one column and one row, a second half mirror 23 ₂ arranged in one column and two rows, and two columns and two rows. The third half mirror 233 ₃ to be formed, the fourth half mirror 234 arranged in 3 columns and 1 row, the _5th half mirror 235 arranged in 3 columns and 2 rows, and ₄ columns 2 It is arranged in a matrix (also called a matrix) of 5 columns and 2 rows consisting of a _6th half mirror 236 arranged in a row and a _7th half mirror 237 arranged in 5 columns and 1 row. It is composed of _{seven half} mirrors 231 to 237.

The terahertz wave emitted from the oscillator 21 passes through the _first half mirror 231 and the _second half mirror 232 in the Z direction, and becomes the _first emitted light 261 on the leftmost side of the paper. The terahertz wave reflected to the right of the paper surface by the second half mirror 23 ₂ is reflected by the third half mirror 23 ₃ and reflected in the Z direction, and becomes the second _second emitted light 262 from the left side of the paper surface. Become. The terahertz wave reflected to the right of the paper surface by the _first half mirror 231 is reflected by the _fourth half mirror 234 and transmitted through the _fifth half mirror 235 in the Z direction, and is the third from the left side of the paper surface. It becomes the _third emitted light 263. The terahertz wave reflected to the right of the paper surface by the _fifth half mirror 235 is reflected in the Z direction by the _sixth half mirror 236 to become the _fourth emitted light 264 from the left side of the paper surface. The terahertz wave transmitted to the right of the paper surface by the fourth _half mirror 231 is reflected in the Z direction by the _seventh half mirror 237 to become the _fifth emitted light 265 from the left side of the paper surface.

The first half mirror 23 ₁ , the second half mirror 23 ₂ , the _fourth half mirror 234, the _fifth half mirror 235, and the _seventh half mirror 237 have, for example, carrier densities. A 1 × 10 ¹² cm ^-3 silicon wafer can be used. For example, a silicon wafer having a thickness of 601 μm has a transmittance of 36 GHz and a reflectance of 64% at 60 GHz.

For the _third half mirror 233 and the _sixth half mirror 236, for example, a silicon wafer having a carrier density of 5.1 × 10 ¹⁵ cm ^-3 can be used. For example, a silicon wafer having a thickness of 628 μm has a transmittance of 0% and a reflectance of 57% at 60 GHz.

The intensity of the first to _fifth emitted lights 26 ₁ to 265 can be calculated from the transmittance and reflectance of the first to _seventh half mirrors 23 ₁ to 237, where the output from the oscillator 21 is 100. The output is as shown below. The numbers shown in FIG. 4 indicate the intensities of the transmitted wave 3, the reflected wave 4, and the emitted light in the _first to _seventh half mirrors 231 to 237.
Intensity of first emitted light: 13
Intensity of second emitted light: 13
Intensity of third emitted light: 14.7
Fourth emission intensity: 14.9
Intensity of fifth emitted light: 14.7
Total: 70.3

As shown in FIG. 4, the intensities of the first to _fifth emitted lights 26 ₁ to 265 are 13, 13, 14.7, 14.9, and 14.7, respectively, for a total of 70.3. It can be seen that the output from is almost uniform. For example, the spacing between the _first to _seventh half mirrors 231 to 237, that is, the spacing between rows is about 25 mm to 50 mm, and the light flux of the terahertz wave incident on _{each half} mirror 231 to 237 spreads appropriately. If so, the terahertz wave irradiation device 20 of the present invention becomes a line light source of about 10 cm to 20 cm at 60 GHz.

(60 GHz configuration example 2)
FIG. 5 is a diagram showing configuration example 2 of a plurality of half mirrors 23 at 60 GHz. The plurality of half mirrors 23 are arranged in a tenth half mirror 23 ₁₀ arranged in one column and one row, an eleventh half mirror 23 ₁₁ arranged in one column and three rows, and two columns and three rows. The twelfth half mirror 23 ₁₂ arranged, the thirteenth half mirror 23 ₁₃ arranged in three columns and one row, the fourteenth half mirror 23 ₁₄ arranged in three columns and two rows, and the three columns 3 The 15th half mirror 23 ₁₅ arranged in a row, the 16th half mirror 23 ₁₆ arranged in 4 columns and 3 rows, and the 17th half mirror 23 ₁₇ arranged in 5 columns and 2 rows. It is arranged in a matrix of 6 columns and 3 rows consisting of an 18th half mirror 23 ₁₈ arranged in 5 columns and 3 rows and a 19th half mirror 23 ₁₉ arranged in 6 columns and 1 row. It is composed of eight half mirrors 23 ₁₀ to 23 ₁₉ .

As the tenth half mirror 23 ₁₀ , the eleventh half mirror 23 ₁₁ , and the thirteenth half mirror 23 ₁₃ , for example, a silicon wafer having a carrier density of 2.2 × 10 ¹³ cm ^-3 can be used. For example, a silicon wafer having a thickness of 301 μm has a transmittance of 29% and a reflectance of 64% at 60 GHz.

For the twelfth half mirror 23 ₁₂ and the nineteenth half mirror 23 ₁₉ , for example, a silicon wafer having a carrier density of 2.8 × 10 ¹⁴ cm ^-3 can be used. A silicon wafer having a thickness of 559 μm has a transmittance of 26 GHz and a reflectance of 50% at 60 GHz.

For the 14th half mirror 23 ₁₄ , the 15th half mirror 23 ₁₅ , and the 18th half mirror 23 ₁₈ , for example, a silicon wafer having a carrier density of 1 × 10 ¹² cm ^-3 can be used. A silicon wafer having a thickness of 601 μm has a transmittance of 36 GHz and a reflectance of 64% at 60 GHz.

For the 16th half mirror 23 ₁₆ and the 17th half mirror 23 ₁₇ , for example, a silicon wafer having a carrier density of 8.8 × 10 ¹⁸ cm ^-3 can be used. A silicon wafer having a thickness of 520 μm has a transmittance of 0% and a reflectance of 85% at 60 GHz.

The terahertz wave emitted from the oscillator 21 passes through the tenth half mirror 23 ₁₀ and the eleventh half mirror 23 ₁₁ in the Z direction, and becomes the eleventh emitted light 26 ₁₁ on the leftmost side of the paper. The terahertz wave reflected to the right of the paper surface by the eleventh half mirror 23 ₁₁ is reflected by the twelfth half mirror 23 ₁₂ and reflected in the Z direction, and is reflected by the twelfth emitted light 26 ₁₂ from the left side of the paper surface. Become.

The terahertz wave reflected to the right of the paper surface by the tenth half mirror 23 ₁₀ is reflected by the thirteenth half mirror 23 ₁₃ and is transmitted through the fourteenth and fifteenth half mirrors 23 ₁₄ and 23 ₁₅ in the Z direction. , The thirteenth emitted light 26 ₁₃ is the third from the left side of the paper. At this time, the terahertz wave transmitted through the twelfth half mirror 23 ₁₂ is reflected by the fifteenth half mirror 23 ₁₅ and superposed on the thirteenth emitted light 26 ₁₃ .
Here, when the terahertz wave transmitted through the twelfth half mirror 23 ₁₂ is not superimposed as the thirteenth emitted light 26 ₁₃ , an absorber that absorbs the terahertz wave transmitted through the twelfth half mirror 23 ₁₂ is used. It may be provided between the twelfth half mirror 23 ₁₂ and the fifteenth half mirror 23 ₁₄ . Further, the absorber may be attached to the transmissive surface of the twelfth half mirror 23 ₁₂ , that is, the back surface of the twelfth half mirror 23 ₁₂ .

The terahertz wave reflected to the right of the paper surface by the fifteenth half mirror 23 ₁₅ is reflected in the Z direction by the sixteenth half mirror 23 ₁₆ to become the fourth emitted light 26 ₁₄ from the left side of the paper surface. The terahertz wave transmitted to the right of the paper surface by the 14th half mirror 23 ₁₄ is reflected in the Z direction by the 17th half mirror 23 ₁₇ and is transmitted through the 18th half mirror 23 ₁₈ to be the fifth from the left side of the paper surface. The fifteenth emission light 26 ₁₅ of the above. The terahertz wave transmitted to the right of the paper surface by the tenth half mirror 23 ₁₀ is transmitted to the right of the paper surface by the thirteenth half mirror 23 ₁₃ and reflected in the Z direction by the nineteenth half mirror 23 ₁₉ to be reflected on the left side of the paper surface. It becomes the sixth and sixth emission light 26 ₁₆ .

The intensity of the eleventh to sixteenth emitted lights 26 ₁₁ to 26 ₁₆ can be calculated from the transmittance and the reflectance of the tenth to nineteenth half mirrors 23 ₁₀ to 23 ₁₉ with the output from the oscillator 21 as 100. The output is as shown below. The numbers shown in FIG. 5 indicate the intensities of the transmitted wave 3, the reflected wave 4, and the emitted light in each of the half mirrors 23 ₁₀ to 23 ₁₉ .
Intensity of the eleventh emitted light: 8.4
Intensity of the twelfth emitted light: 9.3
Intensity of the thirteenth emitted light: 8.4
Intensity of the 14th emitted light: 9.5
Intensity of 15th emitted light: 8.0
Intensity of the 16th emitted light: 9.3
Total: 52.9

As shown in FIG. 5, the intensities of the 11th to 16th emitted lights 26 ₁₁ to 26 ₁₆ are 8.4, 9.3, 8.4, 9.5, 8.0, and 9.3, respectively. The total is 52.9, and it can be seen that the output from each column is almost uniform. For example, the interval between the 10th to 19th half mirrors 23 ₁₀ to 23 ₁₉ is set to about 20 mm to 40 mm, and the light flux of the terahertz wave incident on each half mirror 23 ₁₀ to 23 ₁₉ spreads appropriately. If so, the terahertz wave irradiation device 20 of the present invention becomes a line light source of about 10 cm to 20 cm at 60 GHz.

(90 GHz configuration example 1)
FIG. 6 is a diagram showing configuration example 1 of a plurality of half mirrors 23 at 90 GHz. The plurality of half mirrors 23 are arranged in a 21st half mirror 23 ₂₁ arranged in 1 column and 1 row, a 22nd half mirror 23 ₂₂ arranged in 1 column and 3 rows, and 2 columns and 1 row. The 23rd half mirror 23 ₂₃ , the 24th half mirror 23 ₂₄ arranged in 2 columns and 2 rows, the 25th half mirror 23 ₂₅ arranged in 3 columns and 3 rows, and 4 columns 2 The 26th half mirror 23 ₂₆ arranged in a row, the 27th half mirror 23 ₂₇ arranged in a row of 5 columns, and the 21st to the 21st arranged in a matrix of 5 columns and 3 rows. It is composed of seven half mirrors 23 ₂₁ to 23 ₂₇ of 27.

The terahertz wave emitted from the oscillator 21 passes through the 21st half mirror 23 ₂₁ and the 22nd half mirror 23 ₂₂ in the Z direction, and becomes the 21st emitted light 26 ₂₁ on the leftmost side of the paper. The terahertz wave reflected to the right of the paper surface by the 21st half mirror 23 ₂₁ is reflected in the Z direction by the 23rd half mirror 23 ₂₃ , passes through the 24th half mirror 23 ₂₄ , and is the second from the left side of the paper surface. It becomes the second emission light 26 ₂₂ . The terahertz wave reflected to the right of the paper surface by the 22nd half mirror 23 ₂₂ is reflected by the 25th half mirror 23 ₂₅ and becomes the 23rd emitted light 26 ₂₃ which is the third from the left side of the paper surface. The terahertz wave reflected to the right of the paper surface by the 24th half mirror 23 ₂₄ is reflected in the Z direction by the 26th half mirror 23 ₂₆ to become the fourth emitted light 26 ₂₄ from the left side of the paper surface. The terahertz wave transmitted to the right of the paper surface by the 21st half mirror 23 ₂₁ is transmitted through the 23rd half mirror 23 ₂₃ and reflected in the Z direction by the 27th half mirror 23 ₂₇ , and is the fifth from the left side of the paper surface. It becomes the 25th emission light 26 ₂₅ .

As the 21st half mirror 23 ₂₁ , the 22nd half mirror 23 ₂₂ and the 23rd half mirror 23 ₂₃ , for example, a silicon wafer having a carrier density of 2.2 × 10 ¹³ cm ^-3 can be used. For example, a silicon wafer having a thickness of 301 μm has a transmittance of 25% and a reflectance of 58% at 90 GHz.

As the 24th half mirror 23 ₂₄ , for example, a silicon wafer having a carrier density of 2.8 × 10 ¹⁴ cm ^-3 can be used. For example, a silicon wafer having a thickness of 559 μm has a transmittance of 33% and a reflectance of 33% at 90 GHz.

For the 25th to 27th half mirrors 23 ₂₅ to 23 ₂₇ , for example, a silicon wafer having a carrier density of 8.8 × 10 ¹⁸ cm ^-3 can be used. For example, a silicon wafer having a thickness of 520 μm has a transmittance of 0% and a reflectance of 80% at 90 GHz.

The intensity of the 21st to 25th emitted lights 26 ₂₁ to 26 ₂₅ can be calculated from the transmittance and the reflectance of the 21st to 27th half mirrors 23 ₂₁ to 23 ₂₇ , where the output from the oscillator 21 is 100. The output is as shown below. The numbers shown in FIG. 6 indicate the intensities of the transmitted wave 3 and the reflected wave 4 in each of the half mirrors 23 ₂₁ to 23 ₂₇ when the output from the oscillator 21 is 100.
Intensity of the 21st emitted light: 6.3
Intensity of 22nd emitted light: 11.1
Intensity of the 23rd emitted light: 11.6
Intensity of the 24th emitted light: 8.9
Intensity of 25th emitted light: 11.6
Total: 49.5

As shown in FIG. 6, the intensities of the 21st to 25th emitted lights 26 ₂₁ to 26 ₂₅ are 6.3, 11.1, 11.6, 8.9, and 11.6, respectively, for a total of 49.5. It can be seen that the output is. For example, when the distance between the 21st to 27th half mirrors 23 ₂₁ to 23 ₂₇ , that is, the distance between rows is about 25 mm to 50 mm, and the light source of the terahertz wave incident on each half mirror has an appropriate spread. The terahertz wave irradiation device 20 of the present invention is a line light source of about 10 cm to 20 cm at 90 GHz. Here, the intensity of the 21st emitted light 26 ₂₁ is 6.3, which is lower than the intensity of the other 22nd to 25th emitted lights 26 ₂₂ to 26 ₂₅ . Therefore, when the intensity distribution of the emitted light of the line light source is emphasized, only the 22nd to 25th emitted light 26 ₂₂ to 26 ₂₅ may be used. The total output at this time is 43.2, and the outputs from each column are almost uniform. In this case, the absorber that absorbs the terahertz wave transmitted through the 22nd half mirror 23 ₂₂ may be attached to the surface on the transmitting side, that is, the back surface of the 22nd half mirror 23 ₂₂ .

(90 GHz configuration example 2)
FIG. 7 is a diagram showing configuration example 2 of a plurality of half mirrors 23 at 90 GHz. The plurality of half mirrors 23 are arranged in the 31st half mirror 23 ₃₁ arranged in 1 column and 1 row, the 32nd half mirror 23 ₃₁ arranged in 1 column and 2 rows, and 2 columns and 2 rows. 33rd half mirror 23 ₃₃ , 34th half mirror 23 ₃₄ arranged in 3 columns and 1 row, 35th half mirror 23 ₃₅ arranged in 3 columns and 2 rows, and 4 columns 2 31st to 37th arranged in a matrix of 5 columns and 2 rows consisting of a 36th half mirror 23 ₃₆ arranged in a row and a 37th half mirror 23 ₃₇ arranged in 5 columns and 1 row. It is composed of seven half mirrors 23 ₃₁ to 23 ₃₇ .

The 31st half mirror 23 ₃₁ , the 32nd half mirror 23 ₃₂ , the 34th half mirror 23 ₃₄ , and the 35th half mirror 23 ₃₅ have, for example, a carrier density of 2.2 × 10 ¹³ cm ^-3 . Silicone wafers can be used. For example, a silicon wafer having a thickness of 301 μm has a transmittance of 25% and a reflectance of 58% at 90 GHz.

For the 33rd half mirror 23 ₃₃ and the 37th half mirror 23 ₃₇ , for example, a silicon wafer having a carrier density of 5.1 × 10 ¹⁵ cm ^-3 can be used. For example, a silicon wafer having a thickness of 628 μm has a transmittance of 0% and a reflectance of 67% at 90 GHz.

As the 36th half mirror 23 ₃₆ , for example, a silicon wafer having a carrier density of 1 × 10 ¹² cm ^-3 can be used. For example, a silicon wafer having a thickness of 601 μm has a transmittance of 58 Hz and a reflectance of 42% at 90 GHz.

The terahertz wave emitted from the oscillator 21 passes through the 31st half mirror 23 ₃₁ and the 32nd half mirror 23 ₃₂ in the Z direction, and becomes the 31st emitted light 26 ₃₁ on the leftmost side of the paper. The terahertz wave reflected to the right of the paper surface by the 32nd half mirror 23 ₃₂ is reflected in the Z direction by the 33rd half mirror 23 ₃₃ to become the second 32nd emitted light 26 ₃₂ from the left side of the paper surface. The terahertz wave reflected to the right of the paper surface by the 31st half mirror 23 ₃₁ is reflected in the Z direction by the 34th half mirror 23 ₃₄ , passes through the 35th half mirror 23 ₃₅ , and is the third from the left side of the paper surface. It becomes the 33rd emission light 26 ₃₃ of the above. The terahertz wave reflected to the right of the paper surface by the 35th half mirror 23 ₃₅ is reflected in the Z direction by the 36th half mirror 23 ₃₆ to become the fourth emitted light 26 ₃₄ from the left side of the paper surface. The terahertz wave transmitted through the 34th half mirror 23 ₃₄ to the right of the paper surface is reflected in the Z direction by the 37th half mirror 23 ₃₇ to become the fifth emitted light 26 ₃₅ from the left side of the paper surface.

The intensity of the 31st to 35th emitted light 26 ₃₁ to 26 ₃₅ can be calculated from the transmittance and the reflectance of the 31st to 37th half mirrors 23 ₃₁ to 23 ₃₇ , where the output from the oscillator 21 is 100. The output is as shown below. The numbers shown in FIG. 7 indicate the intensities of the transmitted wave 3, the reflected wave 4, and the emitted light in each of the half mirrors 23 ₃₁ to 23 ₃₇ .
Intensity of the 31st emitted light: 6.3
Intensity of the 32nd emitted light: 8.4
Intensity of the 33rd emitted light: 8.4
Intensity of the 34th emitted light: 8.4
Intensity of the 35th emitted light: 8.2
Total: 39.7

As shown in FIG. 7, the intensities of the 31st to 35th emitted lights 26 ₃₁ to 26 ₃₅ are 6.3, 8.4, 8.4, 8.4, and 8.2, respectively, for a total of 39.7. It can be seen that the output from each column is almost uniform. For example, the spacing between the 31st to 37th half mirrors 23 ₃₁ to 23 ₃₇ , that is, the spacing between rows is about 25 mm to 50 mm, and the light flux of the terahertz wave incident on each half mirror 23 ₃₁ to 23 ₃₇ spreads appropriately. If so, the terahertz wave irradiation device 20 of the present invention becomes a line light source of about 10 cm to 20 cm at 90 GHz.

(140 GHz configuration example 1)
FIG. 8 is a diagram showing configuration example 1 of a plurality of half mirrors 23 at 140 GHz. As shown in FIG. 8, the plurality of half mirrors 23 include a 41st half mirror 23 ₄₁ arranged in 1 column and 1 row, and a 42nd half mirror 23 ₄₂ arranged in 1 column and 2 rows. The 43rd half mirror 23 ₄₃ arranged in 2 columns and 2 rows, the 44th half mirror 23 ₄₄ arranged in 3 columns and 1 row, and the 45th half mirror arranged in 3 columns and 2 rows. It is arranged in a matrix of 5 columns and 2 rows consisting of 23 ₄₅ , a 46th half mirror 23 ₄₆ arranged in 4 columns and 2 rows, and a 47th half mirror 23 ₄₇ arranged in 5 columns and 1 row. It is composed of seven half mirrors 23 ₄₁ to 23 ₄₇ , which are 41st to 47th to be installed. This configuration is the same as the 60 GHz configuration example 1 shown in FIG.

The 41st half mirror 23 ₄₁ , the 42nd half mirror 23 ₄₂ , the 44th half mirror 23 ₄₄ , the 45th half mirror 23 ₄₅ , and the 7th half mirror 23 ₄₇ have a carrier density of 1 ×. 10 ¹² cm ^-3 silicon wafers can be used. For example, a silicon wafer having a thickness of 601 μm has a transmittance of 36% at 140 GHz and a reflectance of 64%, which are the same values as in Configuration Example 1 of 60 GHz shown in FIG.

For the 43rd half mirror 23 ₄₃ and the 46th half mirror 23 ₄₆ , a silicon wafer having a carrier density of 5.1 × 10 ¹⁵ cm ^-3 can be used. For example, a silicon wafer having a thickness of 628 μm has a transmittance of 0% and a reflectance of 55% at 140 GHz. This transmittance is 0% as in the 60 GHz configuration example 1 shown in FIG. 4, but the reflectance is 55%, which is slightly lower than 57% of the 60 GHz configuration example 1 shown in FIG.

The terahertz wave emitted from the oscillator 21 is transmitted in the Z direction by the 41st half mirror 23 ₄₁ and the 42nd half mirror 23 ₄₂ , and becomes the 41st emitted light 26 ₄₁ on the leftmost side of the paper. The terahertz wave reflected to the right of the paper surface by the 42nd half mirror 23 ₄₂ is reflected by the 43rd half mirror 23 ₄₃ and reflected in the Z direction to become the second emitted light 26 ₄₂ from the left side of the paper surface. .. The terahertz wave reflected to the right of the paper surface by the 41st half mirror 23 ₄₁ is reflected by the 44th half mirror 23 ₄₄ and transmitted through the 45th half mirror 23 ₄₅ in the Z direction, and is the third from the left side of the paper surface. It becomes the 43rd emission light 26 ₄₃ . The terahertz wave reflected to the right of the paper surface by the 45th half mirror 23 ₄₅ is reflected in the Z direction by the 46th half mirror 23 ₄₆ to become the fourth emitted light 26 ₄₄ from the left side of the paper surface. The terahertz wave transmitted to the right of the paper surface by the 44th half mirror 23 ₄₄ is reflected in the Z direction by the 47th half mirror 23 ₄₇ to become the fifth emitted light 26 ₄₅ from the left side of the paper surface.

The intensity of the 41st to 45th emitted lights 26 ₄₁ to 26 ₄₅ can be calculated from the transmittance and the reflectance of the 41st to _47th half mirrors 23 ₄₁ to 2347, where the output from the oscillator 21 is 100. The output is as shown below. The numbers shown in FIG. 8 indicate the intensities of the transmitted wave 3, the reflected wave 4, and the emitted light in each of the half mirrors 23 ₄₁ to ₂₃₄₇ .
Intensity of first emitted light: 13
Intensity of second emitted light: 12.7
Intensity of third emitted light: 14.7
Fourth emitted light intensity: 14.4
Intensity of fifth emitted light: 14.7
Total: 69.5

As shown in FIG. 8, the intensities of the 41st to 45th emitted lights 26 ₄₁ to 26 ₄₅ are 13, 12.7, 14.7, 14.4, and 14.7, respectively, for a total of 69.5. It can be seen that the output from the columns is almost uniform. For example, the spacing between the 41st to _47th half mirrors 23 ₄₁ to 2347, that is, the spacing between rows is about 25 mm to 50 mm, and the light flux of the terahertz wave incident on each half mirror 23 ₄₁ to ₂₃₄₇ spreads appropriately. If so, the terahertz wave irradiation device 20 of the present invention becomes a line light source of about 10 cm to 20 cm at 140 GHz.

The arrangement of the 41st to 47th half mirrors 23 ₄₁ to 23 ₄₇ shown in FIG. 8 and the carrier densities of the half mirrors 23 ₄₁ to 23 ₄₇ used have the same configuration as that of the 60 GHz configuration example 1 shown in FIG. Therefore, the intensities of the 41st to 47th emitted lights 26 ₄₁ to 26 ₄₅ at 140 GHz are almost the same.

(140 GHz configuration example 2)
FIG. 9 is a diagram showing configuration example 2 of a plurality of half mirrors 23 at 140 GHz. The plurality of half mirrors 23 are arranged in the 51st half mirror 23 ₅₁ arranged in 1 column and 1 row, the 52nd half mirror 23 ₅₂ arranged in 1 column and 2 rows, and 2 columns and 2 rows. 53rd half mirror 23 ₅₃ , 54th half mirror 23 ₅₄ arranged in 3 columns and 1 row, 55th half mirror 23 ₅₅ arranged in 3 columns and 2 rows, and 4 columns 1 The 56th half mirror 23 ₅₆ arranged in a row, the 57th half mirror 23 ₅₇ arranged in 5 columns and 1 row, and the 58th half mirror 23 ₅₈ arranged in 5 columns and 2 rows. It is composed of eight half mirrors 23 ₅₁ to 23 ₅₈ of the 51st to 58th arranged in 5 columns and 2 rows.

As the 51st half mirror 23 ₅₁ , a silicon wafer having a carrier density of 1 × 10 ¹² cm ^-3 can be used. For example, a silicon wafer having a thickness of 601 μm has a transmittance of 36% at 140 GHz and a reflectance of 64%, which are the same values as in Configuration Example 1 of 60 GHz shown in FIG.

As the 52nd half mirror 23 ₅₂ , for example, a silicon wafer having a carrier density of 2.8 × 10 ¹⁴ cm ^-3 can be used. For example, a silicon wafer having a thickness of 559 μm has a transmittance of 23% and a reflectance of 55% at 140 GHz. The transmittance of 23% is smaller than the transmittance of 26% of the 60 GHz configuration example 1 shown in FIG. 4, and the reflectance is 55%, which is slightly higher than the 50% of the 60 GHz configuration example 1 shown in FIG.

For the 53rd half mirror 23 ₅₃ and the 57th half mirror 23 ₅₇ , a silicon wafer having a carrier density of 5.1 × 10 ¹⁵ cm ^-3 can be used. For example, a silicon wafer having a thickness of 628 μm has a transmittance of 0% and a reflectance of 55% at 140 GHz. This transmittance is 0% as in the 60 GHz configuration example 1 shown in FIG. 4, but the reflectance is 55%, which is slightly lower than 57% of the 60 GHz configuration example 1 shown in FIG.

The 54th half mirror 23 ₅₄ , the 55th half mirror 23 ₅₅ , the 56th half mirror 23 ₅₆ , and the 58th half mirror 23 ₅₈ have, for example, a carrier density of 2.2 × 10 ¹³ cm ^-3 . Silicone wafers can be used. For example, a silicon wafer having a thickness of 301 μm has a transmittance of 68 Hz and a reflectance of 27% at 140 GHz. The transmittance of 68% is larger than the transmittance of 29% of the 60 GHz configuration example 1 shown in FIG. 4, and the reflectance of 27% is lower than the 64% of the 60 GHz configuration example 1 shown in FIG.

The terahertz wave emitted from the oscillator 21 is transmitted in the Z direction by the 51st half mirror 23 ₅₁ and the 52nd half mirror 23 ₅₂ , and becomes the 51st emitted light 26 ₅₁ on the leftmost side of the paper. The terahertz wave reflected to the right of the paper surface by the 52nd half mirror 23 ₅₂ is reflected by the 53rd half mirror 23 ₅₃ and reflected in the Z direction, and becomes the second emitted light 26 ₅₂ from the left side of the paper surface. Become. The terahertz wave reflected to the right of the paper surface by the 51st half mirror 23 ₅₁ is reflected by the 54th half mirror 23 ₅₄ , transmitted through the 55th half mirror 23 ₅₅ in the Z direction, and is the third from the left side of the paper surface. It becomes the 53rd emission light 26 ₅₃ of the above. The terahertz wave transmitted to the right of the paper surface by the 54th half mirror 23 ₅₄ is reflected in the Z direction by the 56th half mirror 23 ₅₆ to become the fourth emitted light 26 ₅₄ from the left side of the paper surface. The terahertz wave transmitted to the right of the paper surface by the 56th half mirror 23 ₅₆ is reflected in the Z direction by the 57th half mirror 23 ₅₇ , and is transmitted in the Z direction through the 58th half mirror 23 ₅₈ from the left side of the paper surface. It becomes the fifth 55th emitted light 26 ₅₅ .

The intensity of the 51st to 55th emitted light 26 ₅₁ to 26 ₅₅ can be calculated from the transmittance and the reflectance of the 51st to 58th half mirrors 23 ₅₁ to 26 ₅₈ , where the output from the oscillator 21 is 100. The output is as shown below. The numbers shown in FIG. 9 indicate the intensities of the transmitted wave 3, the reflected wave 4, and the emitted light in each of the half mirrors 23 ₅₁ to 26 ₅₈ .
Intensity of the 51st emitted light: 8.3
Intensity of the 52nd emitted light: 10.9
Intensity of the 53rd emitted light: 11.8
Intensity of the 54th emitted light: 11.8
Intensity of 55th emitted light: 11.1
Total: 53.9

As shown in FIG. 9, the intensities of the 51st to 55th emitted lights 26 ₅₁ to 26 ₅₅ are 8.3, 10.9, 11.8, 11.8 and 11.1, respectively, for a total of 53.9. It can be seen that the output from each column is almost uniform. For example, the spacing between the 51st to 58th half mirrors 23 ₅₁ to 26 ₅₈ , that is, the spacing between rows is about 25 mm to 50 mm, and the light flux of the terahertz wave incident on each half mirror 23 ₅₁ to 26 ₅₈ spreads appropriately. If so, the terahertz wave irradiation device 20 of the present invention becomes a line light source of about 10 cm to 20 cm at 140 GHz.

(140 GHz configuration example 3)
FIG. 10 is a diagram showing configuration example 3 of a plurality of half mirrors 23 at 140 GHz. The plurality of half mirrors 23 are arranged in the 61st half mirror 23 ₆₁ arranged in 1 column and 1 row, the 62nd half mirror 23 ₆₂ arranged in 1 column and 2 rows, and 2 columns and 1 row. 63rd half mirror 23 ₆₃ , 64th half mirror 23 ₆₄ arranged in 3 columns and 2 rows, 65th half mirror 23 ₆₅ arranged in 4 columns and 1 row, and 5 columns 1 It is composed of six half mirrors 23 ₆₁ to 23 ₆₆ , which are arranged in two rows in five columns and 66th half mirrors 23 ₆₆ arranged in a row.

The 61st half mirror 23 ₆₁ , the 63rd half mirror 23 ₆₃ , and the 65th half mirror 23 ₆₅ can use a silicon wafer having a carrier density of 2.2 × 10 ¹³ cm ^-3 . For example, a silicon wafer having a thickness of 301 μm has a transmittance of 68 Hz and a reflectance of 27% at 140 GHz. The transmittance of 68% is larger than the transmittance of 29% of the 60 GHz configuration example 1 shown in FIG. 4, and the reflectance of 27% is lower than the 64% of the 60 GHz configuration example 1 shown in FIG.

For the 62nd half mirror 23 ₆₂ and the 64th half mirror 23 ₆₄ , a silicon wafer having a carrier density of 8.8 × 10 ¹⁸ cm ^-3 can be used. For example, a silicon wafer having a thickness of 520 μm has a transmittance of 0% and a reflectance of 75% at 140 GHz. This transmittance is 0% as in the 60 GHz configuration example 1 shown in FIG. 4, but the reflectance is 75%, which is slightly lower than the 85% of the 60 GHz configuration example 1 shown in FIG.

For the 66th half mirror 23 ₆₆ , a silicon wafer having a carrier density of 5.1 × 10 ¹⁵ cm ^-3 can be used. For example, a silicon wafer having a thickness of 628 μm has a transmittance of 0% and a reflectance of 55% at 140 GHz. This transmittance is 0% as in the 60 GHz configuration example 1 shown in FIG. 4, but the reflectance is 55%, which is slightly lower than 57% of the 60 GHz configuration example 1 shown in FIG.

In the 140 GHz configuration examples 1 and 2, the terahertz waves emitted from the oscillator 21 are all incident from above the 41st and _51st half mirrors 23 ₄₁ and 2351 arranged in one column and one row. This is an example. On the other hand, in the plurality of half mirrors 23 of the 140 GHz configuration example 3, the terahertz wave emitted from the oscillator 21 is arranged in one column and one row, unlike the 140 GHz configuration examples 1 and 2. The half mirror 23 ₆₁ of the above was configured to be incident from the side.

The terahertz wave emitted from the oscillator 21 is incident from the side of the 61st half mirror 23 ₆₁ , is transmitted through the 61st half mirror 23 ₆₁ to the right of the paper surface, and is reflected in the Z direction by the 63rd half mirror 23 ₆₃ . Then, it becomes the first _61st emitted light 2661 from the left side of the paper. The terahertz wave reflected in the Z direction by the 61st half mirror 23 ₆₁ is reflected to the right of the paper surface by the 62nd half mirror 23 ₅₃ , and further reflected in the Z direction by the 64th half mirror 23 ₆₄ to be reflected on the paper surface. It is the 62nd emitted light 26 ₆₂ , which is the second from the left side. The terahertz wave transmitted through the 63rd half mirror 23 ₆₃ to the right of the paper surface is further reflected in the Z direction by the 65th half mirror 23 ₆₅ to become the third emitted light 26 ₆₃ from the left side of the paper surface. .. The terahertz wave transmitted through the 65th half mirror 23 ₆₅ to the right of the paper surface is reflected in the Z direction by the 66th half mirror 23 ₆₆ to become the 64th emitted light 26 ₆₄ which is the fourth from the left side of the paper surface.

The intensity of the 61st to 64th emitted light 26 ₆₁ to 26 ₆₄ can be calculated from the transmittance and the reflectance of the 61st to 66th half mirrors 23 ₆₁ to 26 ₆₆ , where the output from the oscillator 21 is 100. The output is as shown below. The numbers shown in FIG. 10 indicate the intensities of the transmitted wave 3, the reflected wave 4, and the emitted light in each of the half mirrors 23 ₆₁ to 26 ₆₆ .
Intensity of the 61st emitted light: 18.4
Intensity of the 62nd emitted light: 15.2
Intensity of the 63rd emitted light: 12.5
Intensity of the 64th emitted light: 17.3
Total: 63.4

As shown in FIG. 10, the intensities of the 61st to 64th emitted lights 26 ₆₁ to 26 ₆₄ are 18.4, 15.2, 12.5, and 17.3, respectively, which are 63.4 in total, from each column. It can be seen that the output of is a substantially concave output distribution with high strength at both ends. For example, the spacing between the 61st to 64th half mirrors 23 ₆₁ to 26 ₆₆ , that is, the spacing between rows is about 25 mm to 50 mm, and the light flux of the terahertz wave incident on each half mirror 23 ₆₁ to 26 ₆₆ spreads appropriately. The terahertz wave irradiation device 20 of the present invention becomes a line light source of about 10 cm to 20 cm at 140 GHz.
By changing the configuration in this way, it is possible to obtain a uniform output distribution in a line shape or a convex output distribution by setting various transmittances or reflectances of the plurality of half mirrors 23, or , It can be set to obtain a desired output distribution according to the irradiation target and the irradiation purpose. Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

As Example 1, a half mirror 1 was made using a silicon wafer. A silicon wafer is an N-type crystal manufactured by the CZ method (Czochralski method) or FZ method (floating zone method) with a diameter of 6 inches and oriented (100) planes, with a predetermined thickness and a predetermined carrier density. Was used. The silicon wafers used are shown in Table 1. The carrier density was measured by the CV method (capacitive voltage method).

The silicon wafer of No. 1 has a thickness specification of 600 ± 10 μm and a carrier density of 1 × 10 ¹² cm ^-3 . The silicon wafer of No. 2 had a thickness specification of 300 ± 10 μm and a carrier density of 2.2 × 10 ¹³ cm ^-3 . The silicon wafer of No. 3 had a thickness specification of 550 ± 15 μm and a carrier density of 2.8 × 10 ¹⁴ cm ^-3 . The silicon wafer of No. 4 had a thickness specification of 620 ± 15 μm and a carrier density of 5.1 × 10 ¹⁵ cm ^-3 . The silicon wafer of No. 5 had a thickness specification of 525 ± 15 μm and a carrier density of 8.8 × 10 ¹⁸ cm ^-3 . In Table 1, the thickness of the silicon wafer used is actually measured, and the average value of the five measurements is shown as the five-time average thickness (μm). The thickness of the silicon wafer shown below is the average thickness of 5 times.

(Measurement of transmittance and reflectance: 60 GHz)
The transmittance and reflectance of the silicon wafer at 60 GHz were measured by the terahertz wave transmittance and reflectance measuring device 9 shown in FIG. As the terahertz wave oscillator 2, a 60 GHz continuous oscillation (CW oscillation) Gunn diode oscillator (Model GDO-15-6013R manufactured by SPACEK LABS) was used. The output of the Gunn diode oscillator 2 is about 10 mW. As shown in FIG. 2, the silicon wafer is irradiated with a terahertz wave 2a at an incident angle of 45 °, and the transmitted wave 3 and the reflected wave 4 are irradiated with a Schottky barrier diode for 60 GHz (SPACEK LABS, model DV-. It was measured by 2N).

The transmittance and reflectance normalized by setting the output of the terahertz wave 2a to 100 were measured. Table 2 shows the transmittance and reflectance of 60 GHz in the five-level silicon wafer shown in Table 1.

The silicon wafer of No. 1 (carrier density: 1 × 10 ¹² cm ^-3 ) had a transmittance of 36% and a reflectance of 64%. The silicon wafer of No. 2 (carrier density: 2.2 × 10 ¹³ cm ^-3 ) had a transmittance of 29% and a reflectance of 64%. The silicon wafer of No. 3 (carrier density: 2.8 × 10 ¹⁴ cm ^-3 ) had a transmittance of 26% and a reflectance of 50%. The silicon wafer of No. 4 (carrier density: 5.1 × 10 ¹⁵ cm ^-3 ) had a transmittance of 0% and a reflectance of 57%. The silicon wafer of No. 5 (carrier density: 8.8 × 10 ¹⁸ cm ^-3 ) had a transmittance of 0% and a reflectance of 85%.

The carrier densities of the silicon wafers Nos. 1 to 3 were 1 × 10 ¹² cm ^-3 to 2.8 × 10 ¹⁴ cm ^-3 , and it was found that transmitted wave 3 and reflected wave 4 were generated. The data show that the transmittance decreases as the carrier density of the silicon wafer increases. Further, in the silicon wafer of No. 1 (thickness: about 600 μm), since the thickness of the silicon wafer having a transmittance of about 37% is about 1 / α, α can be obtained as about 16.7 cm ^-1 . .. From this, it can be seen that the transmittance can be adjusted by changing the thickness of the silicon wafer.

It was found that the carrier densities of the silicon wafers of Nos. 4 and 5 were 5.1 × 10 ¹⁵ cm ^-3 to 8.8 × 10 ¹⁸ cm ^-3 , and only the reflected wave 4 was generated. From the above data, it can be estimated that the transmittance decreases due to the increase in the carrier density of the silicon wafer, and only the reflected wave 4 is generated when the carrier density increases to some extent. From this, it can be seen that the reflectance can be adjusted by changing the carrier density of the silicon wafer.

(Measurement of transmittance and reflectance: 90 GHz)
The transmittance and reflectance at 90 GHz were measured by the terahertz wave transmittance and reflectance measuring device 9 shown in FIG. 2, similarly to 60 GHz. As the terahertz wave oscillator 2, a 90 GHz continuous oscillation Gunn diode oscillator (Model GW-900P manufactured by SPACEK LABS) was used. The output of the Gunn diode oscillator is about 10 mW. Similar to 60 GHz, the transmitted wave 3 and the reflected wave 4 were focused by a lens 8 manufactured by Teflon (registered trademark) and detected by a Schottky barrier diode (model DXP-10-RPF0 manufactured by millitech).

The transmittance and reflectance normalized by setting the output of the terahertz wave 2a to 100 were measured. Table 3 shows the transmittance and reflectance of 90 GHz in the silicon wafers of the 5th level shown in Table 1.

The silicon wafer of No. 1 (carrier density: 1 × 10 ¹² cm ^-3 ) had a transmittance of 58% and a reflectance of 42%. The silicon wafer of No. 2 (carrier density: 2.2 × 10 ¹³ cm ^-3 ) had a transmittance of 25% and a reflectance of 58%. The silicon wafer of No. 3 (carrier density: 2.8 × 10 ¹⁴ cm ^-3 ) had a transmittance of 33% and a reflectance of 33%. The silicon wafer of No. 4 (carrier density: 5.1 × 10 ¹⁵ cm ^-3 ) had a transmittance of 0% and a reflectance of 67%. The silicon wafer of No. 5 (carrier density: 8.8 × 10 ¹⁸ cm ^-3 ) had a transmittance of 0% and a reflectance of 80%.

At 90 GHz, as in the case of 60 GHz, the transmitted wave 3 and the reflected wave 4 were obtained from the silicon wafers of Nos. 1 to 3, and only the reflected wave 4 was obtained from the silicon wafers of Nos. 4 and 5. From this, it was found that the silicon wafer operates as the half mirror 1 even at 90 GHz as in the case of 60 GHz, and the transmittance and the reflectance can be adjusted by the carrier density and the thickness.

(Measurement of transmittance and reflectance: 140 GHz)
The transmittance and reflectance at 140 GHz were measured by the terahertz wave transmittance and reflectance measuring device 9 shown in FIG. 2, similarly to 60 GHz. As the terahertz wave oscillator 2, an oscillator using an IMPATT diode with continuous oscillation of 140 GHz (manufactured by ELVA-1, model CIDO-06 / 140/20) was used. The output of the IMPATT diode oscillator 2 is approximately 10 mW. Similar to 60 GHz, the transmitted wave 3 and the reflected wave 4 were focused by a lens 8 manufactured by Teflon (registered trademark) and detected by a Schottky barrier diode (model ZBD-06 manufactured by ELVA-1).

The transmittance and reflectance normalized by setting the output of the terahertz wave 2a to 100 were measured. Table 4 shows the transmittance and reflectance of 140 GHz in the silicon wafers of the 5th level shown in Table 1.

At 140 GHz, the transmitted wave 3 and the reflected wave 4 were obtained from the silicon wafers Nos. 1 to 3 and only the reflected wave 4 was obtained from the silicon wafers Nos. 4 and 5 as in the case of 60 GHz. From this, it was found that the silicon wafer operates as a half mirror 1 even at 140 GHz as in the case of 60 GHz, and the transmittance or reflectance can be adjusted by the carrier density and the thickness.

As the second embodiment, the terahertz wave irradiation device 20 using the half mirror 23 of the first embodiment will be described.
As a plurality of half mirrors 23 shown in Configuration Example 1 of 90 GHz (see FIG. 6), a terahertz wave irradiation device 20 using seven silicon wafers was manufactured. The silicon wafers used for the half mirror 23 are shown in Table 1, and three silicon wafers of No. 2 (carrier density: 2.2 × 10 ¹³ cm ^-3 ) and silicon wafers of No. 3 (carrier density:: One 2.8 × 10 ¹⁴ cm ^-3 ) and three silicon wafers No. 5 (carrier density: 8.8 × 10 ¹⁴ cm ^-3 ) are used.

FIG. 11 is a schematic plan view of the terahertz wave irradiation device 20 of the second embodiment. Specifically, the irradiation device 20 of the second embodiment includes an optical surface plate with a screw hole, a 90 GHz oscillator 21, a parabolic mirror 22, and half mirrors 23 ₂₁ to 23 ₂₇ composed of seven silicon wafers. Was arranged and configured. Since the configuration of the plurality of half mirrors 23 used is the same as the configuration example 1 of 90 GHz shown in FIG. 6, each half mirror 23 and the emitted light 26 in each row are designated by the same reference numerals as those in FIG. Here, as described in the 90 GHz configuration example 1 shown in FIG. 6, the 22nd to 25th emitted light 26 ₂₂ to 26 ₂₅ were taken out as a line light source with an emphasis on the intensity distribution of the emitted light.

The size of each silicon wafer was 34 mm × 60 mm, and the silicon wafer was attached to seven mirror stands. As shown in FIG. 11, each silicon wafer was set at an angle of approximately 45 ° with respect to the incident terahertz wave.

As the 90 GHz oscillator 21, a Gunn diode oscillator (model GW-900P manufactured by SPACEK LABS) was used as in the first embodiment, and output was performed by the horn antenna 21a. The output of the Gunn diode oscillator was about 10 mW, and the parabolic mirror 22 incident on the 21st half mirror 23 ₂₁ as a predetermined luminous flux.

A 90 GHz Schottky barrier diode (model DXP-10-RPF0 manufactured by millitech) is arranged at the emission unit 25 of the irradiation device 20, and as shown in FIG. 11, a terahertz wave in the X direction, that is, a second to second wave. Five rows of emitted light 26 ₂₂ to 26 ₂₅ were measured.

FIG. 12 is a diagram showing the output distribution of the terahertz wave in the X direction of the terahertz wave irradiation device 20 of the second embodiment, in which the horizontal axis is the distance (mm) in the X direction and the vertical axis is the output of the shotkey barrier diode ( Arbitrary scale). As shown in FIG. 12, five peaks are generated from left to right, and the terahertz wave from the 90 GHz oscillator 21 is converted into a line light source of about 10 cm by half mirrors 23 ₂₁ to 23 ₂₇ made of silicon wafers. It turned out that there was. It is presumed that the difference in the size of each peak shown in FIG. 12 is due to the fact that the angles of the silicon wafers in the first row and the second row deviate from 45 °.

The present invention can be implemented in various forms without departing from the spirit of the present invention.
For example, in Example 2 described above, a plurality of half mirrors 23 arranged in a matrix of 5 columns and 3 rows are shown, but it is clear that the configuration of other half mirrors 23 can be used without limitation. ..

In the above-described second embodiment, the seven half mirrors 23 are arranged in a matrix of 5 columns and 3 rows, but the row is not limited to the arrangement of 3 rows and may be 2 rows or used. It is clear that the thickness and carrier density of the silicon wafer can be changed as appropriate.

The above embodiment can be appropriately changed within the scope of the present invention. For example, an example in which the terahertz wave irradiation device 20 is used for the inspection device 10 of the paper leaves 11 has been described, but the present invention is not limited to anything, and the terahertz wave irradiation device 20 can be used for other purposes. It may be a device that irradiates a terahertz wave, or may be a device that irradiates a living body such as a human body with a terahertz wave.

In the above embodiment, as the inspection device 10 using the irradiation device 20, the terahertz wave transmitted through the paper sheets 11 is detected by the detection device 30, but the present invention is not limited to this. By providing a detection unit on the same side as the irradiation device 20 for the paper leaves 11, it is also possible to configure the terahertz waves reflected on the front surface or the back surface of the paper leaves 11 to be detected.

1 Half mirror 2 Antenna 3 Transmittance 4 Reflected wave 5 Transmitted wave detector 6 Reflected wave detector 7, 8 Condensing parts 9 Terahertz wave transmittance and transmittance measuring device 10 Inspection device 11 Paper sheets 12 Transport device 12a Irradiation position 13 Transport guide 20 Irradiation device 21 Oscillator 21a Antenna (horn antenna)
22 Condensing parts (parabolic mirror)
23 Multiple half mirrors 25 Emission unit 26 Emission light 30 Detection device 31 Optical component for condensing 32 Detection element 33 Detection element group 34 Information processing unit 35 Printed circuit board

Claims (9)

A half mirror of a terahertz wave composed of a silicon wafer and in which the transmittance or reflectance for a terahertz wave incident on the silicon wafer is set by the carrier density of the silicon wafer. The terahertz wave half mirror according to claim 1, wherein the transmittance is set by the thickness of the silicon wafer. Terahertz wave oscillator and
A condensing component that uses the terahertz wave as a predetermined luminous flux,
Multiple half mirrors that transmit and reflect or reflect terahertz waves,
Equipped with
The plurality of half mirrors are arranged in a matrix at predetermined locations, and the plurality of half mirrors are arranged in a matrix.
The luminous flux is incident from the upper side or the lateral side of one end or the other end of the row of the plurality of half mirrors.
A terahertz wave irradiation device that emits the terahertz wave in a line from the lower end side of the row by transmission and reflection in the plurality of half mirrors. The terahertz wave irradiation device according to claim 3, wherein the transmittance or reflectance of the plurality of half mirrors is set so that the terahertz waves emitted in a line shape have a predetermined output distribution. The terahertz wave irradiation device according to claim 3, wherein the half mirror is a silicon wafer. The terahertz wave irradiation device according to claim 3, wherein the plurality of half mirrors are a combination of silicon wafers having different carrier densities. The terahertz wave irradiation device according to claim 3, wherein the plurality of half mirrors are a combination of silicon wafers having different thicknesses. The terahertz wave irradiation device according to claim 3, further comprising a holding portion for holding each half mirror of the plurality of half mirrors at a predetermined angle. The terahertz wave irradiation device according to claim 3, further comprising a case for the irradiation device, wherein the oscillator is connected to the case for the irradiation device.

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