JPH11166859A - Optical readout type radiation-displacement conversion device and imaging device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the accuracy and sensitivity for detecting radiation without using a cooler. SOLUTION: A part to be supported 3 is supported against a base 1 via a leg part 2. The base 1 comprises a thin film member 4 and a reinforcing member 6 reinforcing the thin film member 4. The part to be supported 3 comprises film 8, 9 constituting a dimorph. The films 8, 9 receive infrared radiation (i), convert it into heat, and are displaced according to the heat. The end region of the film 9 function as a read light reflecting part and a half mirror part 11 opposite to the end region receive readout light (j) via a window 5, convert the readout light (j) into interference light having interference strength matching the displacement of the films 8, 9, and emit the interference light in the opposite direction to the impinging direction. An inclined reflecting surface 6a deflecting and reflecting unnecessary readout light (j) is formed on the reinforcing member 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting various kinds of radiation including invisible light such as infrared rays, X-rays, and ultraviolet rays, and more particularly, to an optical readout for converting radiations into optically readable displacements. TECHNICAL FIELD The present invention relates to a radiation-to-displacement conversion device and an imaging device using the same.

[0002]

2. Description of the Related Art Recently, research has been actively conducted on the use of physical information other than information obtained only from the visible light region by detecting invisible light such as infrared rays, X-rays, and ultraviolet rays.
It is expected to be applied to various industrial fields. As an example, the use of infrared light will be described.

[0003] Infrared rays are energy radiated from all objects having a temperature existing on the earth.
An object near 0K emits infrared light having a peak of 8 to 12 μm. By using this infrared ray, it is possible to detect the presence, shape, and temperature of the object even in the dark. Therefore, if this infrared light is used, for example, even at night when there is almost no lighting, it is possible to drive the car as if watching the scenery of daytime, and it is also possible for illegal intruders to enter buildings at night without lighting. It can be easily discovered.

[0004] Because of these advantages, various approaches have been taken to detect infrared light, which is invisible light, since Herschel discovered the infrared light around 1800. Nowadays, two types of detectors have been used as infrared detectors, namely, a quantum infrared detector and a thermal infrared detector.

[0005]

However, even with today's advances in optomechatronics technology, infrared detection is not technically easy, and has not yet been widely used in the general public. The reason will be described below separately for the quantum infrared detector and the thermal infrared detector.

[0006] The quantum infrared detector is a detector that converts photon energy (E: hv) of infrared light into electron energy and detects it. The wavelength of infrared rays that is most useful in the general society is 3 to 12 μm, and the photon energy of this infrared ray is about 0.1 to 0.4 eV. This value is almost equal to the thermal energy of electrons in a normal temperature object. They are equal. Therefore, in order to convert only the font energy of incident infrared rays into electron energy,
The effects of the thermal energy of the electrons must be removed. That is, in the quantum infrared detector, it is essential to cool the detector and remove heat energy.

Usually, in order to suppress this thermal energy to a low level, it is necessary to cool the detector to about -200 ° C. (77 K). However, the cooler for this is large in volume and generates mechanical vibration. Life is short and expensive.
Therefore, the infrared camera using the quantum infrared detector cannot be reduced in size and cost, and is not widely used in the general society.

On the other hand, a conventional thermal infrared detector is
Converts the energy of the incident infrared rays into heat energy,
A change in the temperature of the detector is caused, and a change in the physical property value of the detector due to the change is electrically read. For example, in a resistive bolometer, the resistance value changes when the temperature changes.

This conventional thermal infrared detector does not require a large-scale cooler such as a quantum infrared detector, but has a problem in the detection principle itself. That is, in the conventional thermal infrared detector, although a temperature change of the detector due to only the incident infrared ray has to be detected, a current must be supplied to the detector in order to detect the temperature change.

That is, since the detector generates heat (usually called self-heating) due to a current for detecting a temperature change, it is difficult to detect a temperature change due to only incident infrared rays, and the detection accuracy is reduced. Was.

[0011] Further, the conversion part for converting incident infrared rays into thermal energy detects as much as possible a temperature change depending only on the thermal energy generated by the incident infrared rays.
Although supported in a state of floating from the substrate, it is necessary to build a resistance bolometer or the like in the conversion part floating from the substrate, so it is necessary to electrically connect the conversion part and the substrate with a conductive material. is there. However, since the conductive material has an extremely high thermal conductivity, the conventional thermal infrared detector cannot increase the degree of thermal insulation of the conversion part with respect to the substrate, and the detection accuracy also decreases in this regard. And the sensitivity was also reduced.

Further, the conventional thermal infrared detector has a drawback of low sensitivity. In a conventional thermal infrared detector, for example, an object having a resistance change rate of about 2% when the resistance temperature changes by 1 ° C. is used. The rate of conversion to temperature is at most about 1%. Therefore, even if the temperature of the observation object changes by 1 ° C., the resistance changes only by 0.02%.

Furthermore, in the conventional thermal infrared detector, since the obtained electric signal is extremely weak, the electric signal readout circuit is required to have a very high level of low noise, and the circuit scale is large. Was.

The situation described above is not limited to infrared rays, but also applies to other radiations.

The present invention has been made in view of the above-mentioned circumstances, and has an optical readout type radiation-to-displacement converter which can be used as a radiation detection device having high detection accuracy and sensitivity without requiring a cooler. And an imaging device using the same.

[0016]

According to a first aspect of the present invention, there is provided an optical readout type radiation-to-displacement conversion apparatus comprising: a base; and a supported portion supported by the base. A supported part having a radiation absorption part that receives radiation and converts it into heat, and a displacement part that is displaced with respect to the substrate in accordance with the heat generated in the radiation absorption part; Interfering means for converting the readout light into interference light having an interference state corresponding to the displacement of the displacement unit and emitting the light in the direction opposite to the incident direction of the readout light, and receiving the light by the interference means of the readout light applied Deflecting and reflecting means for deflecting and reflecting most of the light other than the readout light which is converted into the interference light in a direction inclined with respect to a direction in which the interference light is emitted from the interference means. It is a thing.

According to the first aspect, infrared rays, X-rays,
Radiation such as ultraviolet rays is applied to the radiation absorbing portion of the supported portion, and the radiation is absorbed by the radiation absorbing portion and converted into heat.
The displacement part of the supported part is displaced with respect to the base in accordance with the heat generated in the radiation absorbing part. That is, the incident radiation is converted into a displacement of the displacement unit according to the amount. On the other hand, readout light of visible light or other light is applied to the interference means. The interference means converts the received readout light into interference light having an interference state corresponding to the displacement of the displacement unit and emits the readout light in a direction opposite to the incident direction of the readout light. Is converted into a change in the intensity of the interference light. Therefore, the radiation can be detected based on the interference light emitted from the interference means. At this time, since displacement detection by interference light can be performed with high sensitivity, according to the first aspect, radiation can be detected with high sensitivity. In the first aspect,
Unlike the conventional thermal infrared detector described above, instead of converting radiation to a resistance value (electric signal) via heat, the radiation is converted to intensity change of interference light due to readout light via heat and displacement. There is no need to supply current to the supported portion supported by the base, and self-heating does not occur in the supported portion.
Therefore, according to the first aspect, since only the heat due to the incident radiation is detected, the detection accuracy is improved. Needless to say, in the first embodiment, a cooler required in the quantum infrared detector is not required, as in the above-described conventional thermal infrared detector. Further, in the first embodiment, since the radiation is not read out as an electric signal, the reading circuit for a weak electric signal which is required in the above-mentioned conventional thermal infrared detector becomes unnecessary.

By the way, of the irradiated read light, the interference light emitted in the direction opposite to the incident direction of the read light by the interference means is the signal light. That is, if the noise light) is reflected in the same direction as the signal light and mixes with the signal light, the so-called S / N is reduced. In this regard, according to the first aspect, most of the irradiated read light other than the read light that is received by the interference unit and converted into the interference light is reflected by the deflection reflection unit. Since the light is deflected and reflected in a direction inclined with respect to the direction emitted from the interference means, noise light does not mix with the signal light, and S
/ N is improved. As another method, it is conceivable to provide an anti-reflection film for preventing reflection of light other than the interference light emitted in the direction opposite to the incident direction of the read light by the interference means of the irradiated read light. Even in this case, the S / N is improved without noise light being mixed with the signal light.
However, in this case, the noise light is absorbed by the anti-reflection film to generate heat, and the heat is transmitted to the displacement portion, so that the displacement portion is displaced by the heat.
Accordingly, in this case, the noise portion of the readout light is absorbed by the antireflection film and the displacement portion is displaced by the heat transmitted to the displacement portion, and the radiation detection accuracy is reduced. In this regard, according to the first aspect, since the noise light of the read light is reflected by the deflecting / reflecting means, the noise light is not absorbed to generate heat. For this reason, according to the first aspect, since only the heat due to the incident radiation is detected, the detection accuracy is improved. Thus, according to the first aspect, S
/ N and the detection accuracy can be simultaneously improved.

The interference means comprises a reflecting part which forms a part of the supported part and is displaced in accordance with the displacement of the displacing part, and a half mirror fixed to the base so as to face the reflecting part. A half mirror unit that reflects only a part of the received read light. In this case, the reflection section may be configured to form a part of the displacement section. In this case, the structure is simpler than when the reflection section and the displacement section are independent. The number of manufacturing steps is reduced and the cost is reduced.

According to a second aspect of the present invention, there is provided an optical readout radiation-displacement converter according to the first aspect, wherein the base is arranged such that the interference means receives the readout light. And a window for emitting the interference light, wherein the deflecting / reflecting means has a reflecting surface formed in a predetermined area of the substrate except for the window and inclined with respect to the incident direction of the readout light.

The second aspect is an example in which an inclined reflecting surface is employed as a specific example of the deflecting / reflecting means.

An optical readout radiation-displacement converter according to a third aspect of the present invention is the optical readout radiation-displacement converter according to the second aspect, wherein the reflection surface has the window as a bottom and the readout light. Are formed around the window or on both sides of the window so as to form a trapezoidal space extending toward the light incident side.

The third aspect is a specific example of the structure of the reflecting surface in the second aspect.

The optical readout radiation-displacement conversion device according to a fourth aspect of the present invention is the optical readout radiation-displacement conversion device according to the second or third aspect, wherein the base is:
The thin film member having a light-transmitting property with respect to the readout light, and a reinforcing member lining a predetermined region other than a region corresponding to the window in the thin film member, wherein the reflection surface is formed on the reinforcing member. It is a thing.

The fourth aspect is a more specific example of the structure of the reflecting surface in the third aspect. However, since the reflecting surface is formed on a reinforcing member that backs and reinforces the thin film member, The reinforcing member functions not only as a mere member for reinforcement but also as a member for forming a reflection surface, so as to fulfill a composite function, so that the structure is simplified.

An optical readout radiation-displacement converter according to a fifth aspect of the present invention is the optical readout radiation-displacement converter according to the first aspect, wherein the deflection / reflection means comprises:
It has a reflective diffraction grating formed on or provided on the base.

An optical readout radiation-displacement converter according to a sixth aspect of the present invention is the optical readout radiation-displacement converter according to the first aspect, wherein the deflection / reflection means comprises:
It has a microprism array formed on the base or provided on the base.

In the fifth and sixth aspects, a reflection type diffraction grating and a microprism array are respectively exemplified as examples other than the reflection surface of the deflecting / reflecting means.
In the embodiment, the deflecting / reflecting means is not limited to these examples.

According to a seventh aspect of the present invention, there is provided an optical readout type radiation-to-displacement conversion device, comprising: a base; a supported portion supported by the base; A supported part having a displacement part displaced with respect to the base in response to heat generated in the radiation absorbing part, receiving readout light, and causing the received readout light to interfere with the displacement of the displacement part according to the displacement of the displacement part Interfering means for changing the state into interference light having a state and emitting the light, wherein the interference means forms a part of the supported part and is opposed to the reflecting part which is displaced according to the displacement of the displacing part. A half mirror portion fixed to the base as described above, and a half mirror portion that reflects only a part of the received readout light, and as the heat generated by the radiation absorbing portion increases, the As the intensity of the interference light decreases Is obtained by setting the distance between said reflecting portion half mirror unit.

According to the seventh aspect, infrared rays, X-rays,
Radiation such as ultraviolet rays is applied to the radiation absorbing portion of the supported portion, and the radiation is absorbed by the radiation absorbing portion and converted into heat.
Then, the displacement part of the supported part is displaced with respect to the base in accordance with the heat generated in the radiation absorbing part. That is, the incident radiation is converted into a displacement of the displacement unit according to the amount. On the other hand, readout light of visible light or other light is applied to the interference means. The interference means changes the received readout light into interference light having an interference state corresponding to the displacement of the displacement unit and emits the light, so that the radiation irradiated to the radiation absorption unit is eventually
This is converted into a change in the intensity of the interference light. Therefore, the radiation can be detected based on the interference light emitted from the interference means. At this time, since displacement detection by interference light can be performed with high sensitivity, according to the seventh aspect, radiation can be detected with high sensitivity. Further, in the seventh embodiment, unlike the above-described conventional thermal infrared detector, the radiation is not converted into a resistance value (electric signal) through heat, but the radiation is converted into the intensity of the interference light through heat and displacement. Since the change is converted into a change, it is not necessary to supply an electric current to the supported portion supported by the base, and self-heating does not occur in the supported portion. Therefore, according to the seventh aspect, since only heat due to incident radiation is detected, detection accuracy is improved. Needless to say, in the seventh aspect, a cooler that is necessary in the quantum infrared detector is not required, as in the above-described conventional thermal infrared detector. Further, in the seventh aspect, since the radiation is not read out as an electric signal, the readout circuit for a weak electric signal which is required in the above-mentioned conventional thermal infrared detector becomes unnecessary.

As described above, according to the seventh aspect, basically, the same advantages as those of the first aspect can be obtained.

[0032] In the seventh aspect, the interference means forms a part of the supported part and displaces according to the displacement of the displacement part. A fixed half-mirror unit, and a half-mirror unit that reflects only a part of the received readout light, and as the heat generated by the radiation absorbing unit increases, the intensity of the interference light increases. The distance between the reflection part and the half mirror part is set so as to decrease. In the seventh aspect, since the distance between the reflecting portion and the half mirror portion is set as described above, the displacement amount of the displacement portion becomes large even if the radiation incident amount is the same, and the radiation detection is performed. The sensitivity is further improved. That is, when the intensity of the interference light decreases, the read light incident on the interference means by the reduced amount is absorbed by the interference means (the reflecting portion has a larger amount of absorption, that is, the amount of heat generation than the half mirror portion), and is converted into heat. Will be done. Therefore, in the seventh aspect, since the distance between the reflection part and the half mirror part that constitute the interference unit is set as described above, the amount of radiation received by the radiation absorption part increases, thereby When the heat generated by the radiation absorbing portion increases and the heat transmitted to the displacement portion increases, the displacement portion displaces, thereby reducing the intensity of the interference light, and the readout light is absorbed by the reflection portion. As the amount increases, the heat generated in the reflection unit increases, the heat transmitted to the displacement unit further increases, and the displacement unit is further displaced. As described above, in the seventh aspect, the heat generated by the absorption of the readout light by the interference means (particularly, the reflection portion) is skillfully used, and the displacement amount of the displacement portion is increased. As a result, the radiation amount is increased. The detection sensitivity is further improved.

In the seventh aspect, the interfering means changes the received readout light into interference light having an interference state corresponding to the displacement of the displacement section, and changes the readout light in a direction opposite to the incident direction of the readout light. The readout light may be emitted, or the received readout light may be changed to interference light having an interference state corresponding to the displacement of the displacement unit and emitted in the same direction as the incident direction of the readout light.

In the seventh aspect, the reflecting portion may be configured to form a part of the displacement portion. In this case, the reflection portion and the displacement portion are independent. Compared to the case, the structure is simple, the number of manufacturing steps is reduced, and the cost is reduced.

An optical readout radiation-displacement converter according to an eighth aspect of the present invention is the optical readout radiation-displacement converter according to the seventh aspect, wherein the reflectance of the half mirror portion is approximately 1/3. There is something.

When the reflectance of the half mirror portion is set to approximately 1/3 as in the eighth aspect, the amount of read light absorbed by the interference means increases in accordance with the so-called optical cavity principle. Therefore, it is more preferable to improve the detection sensitivity of radiation.

An optical readout radiation-displacement converter according to a ninth aspect of the present invention is the optical readout radiation-displacement converter according to any one of the first to eighth aspects, wherein the displacement portion has a different expansion. It has at least two superimposed layers of different materials having coefficients. The ninth embodiment is an example of a displacement portion, and employs a so-called thermal bimorph structure.

The two layers may be made of different materials having different coefficients of expansion. For example, a combination of a metal film and another metal film or a metal film (Zn, C
d, Pb, Mg, Al, Ni, W, Pt, etc.) and an insulating film (SiO ₂ , SiN, polyimide, etc.), a combination of an insulating film with another insulating film, or the metal Instead of a film, a semiconductor film (polysilicon,
a-Si, InSb, HgCdTe, etc.).

The light-reading type radiation-to-displacement converters according to the first to ninth embodiments convert radiation into a change in interference light using readout light.
It is not necessarily limited to the use of detecting incident radiation. In the first to ninth aspects, the type of incident radiation, the type of readout light, and the like can be appropriately selected depending on the application.

In the first to ninth aspects,
It is preferable that the supported portion is electrically insulated from the base. In the first to ninth aspects, since the above-described principle is used, there is no need to electrically connect the supported portion and the base with a conductive material, unlike the conventional thermal infrared detector described above. Therefore, if the supported portion is electrically insulated from the base without making such an electrical connection, the degree of thermal insulation of the supported portion from the base can be increased. This is preferable because the accuracy and efficiency of radiation conversion can be improved, and the detection accuracy and detection sensitivity of radiation can be improved. However, in the first to ninth aspects, the supported portion and the base may be electrically connected as necessary.

Further, in the first to ninth aspects, the displacement portion may form, for example, a cantilever or a diaphragm. Adopting such a cantilever or diaphragm structure can efficiently convert heat into displacement, which is preferable.

Further, in the first to ninth aspects, the radiation absorbing part may form at least a part of the displacement part. As described above, when the radiation absorbing portion forms at least a part of the displacement portion, the structure is simpler, the number of manufacturing steps is reduced, and the cost is lower than when the radiation absorbing portion and the displacement portion are independent. Become.

In the first to ninth aspects,
The n odd, the ₀ the center wavelength of the radiation lambda, may be provided with a radiation reflecting portion that reflects substantially the radiation being spaced of n [lambda _0/4 from the radiation absorbing portion.
In this case, due to the principle of the so-called optical cavity, the radiation absorptivity of the radiation absorbing portion is increased, and the conversion efficiency from radiation to heat can be increased, and thus, the conversion efficiency of radiation to change in readout light can be increased. And the sensitivity is further increased.

An optical readout radiation-displacement converter according to a tenth aspect of the present invention is the optical readout radiation-displacement converter according to any one of the first to ninth aspects,
The device includes a plurality of the elements as the supported portion and the interference unit as one element, and the elements are arranged one-dimensionally or two-dimensionally.

In the first to ninth embodiments, when radiation is simply detected, only one element (corresponding to a pixel) needs to be provided. However, as in the tenth aspect, 1
If it has a plurality of elements arranged two-dimensionally or two-dimensionally, it forms a one-dimensional or two-dimensional optical image by radiation or captures a one- or two-dimensional image by radiation. Can be.

An imaging device according to an eleventh aspect of the present invention includes an optical readout radiation-displacement conversion device according to the tenth aspect, and the interference means of each of the elements is irradiated with the readout light, respectively. A readout optical system that forms an optical image according to the displacement of the displacement unit of each element based on the interference light emitted from the interference unit of the element.

According to the eleventh aspect, using the optical readout radiation-displacement converter according to the tenth aspect,
An optical image corresponding to the displacement of the displacement section of each element is formed by the readout optical system. Therefore, the radiation image can be formed with high accuracy as the optical image, and the sensitivity is increased. In addition, according to the eleventh aspect, an optical image corresponding to the displacement of the displacement unit of each element is formed based on the readout light. The corresponding optical image can be observed with the naked eye. In the case of using a conventional infrared imaging device, it is impossible to observe an infrared image unless an image is displayed on a display device based on an electric signal or image data after conversion into an electric signal, In the eleventh aspect, when visible light is used as the readout light, the radiation image can be observed with the naked eye without intervening electric signals or image data.

The imaging apparatus according to a twelfth aspect of the present invention is the imaging apparatus according to the eleventh aspect, further comprising an imaging unit for imaging the optical image. As described above, when the image pickup device for picking up an optical image formed by the readout optical system is provided, an image by radiation can be picked up in the same manner as a conventional infrared image pickup device.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical readout type radiation-to-displacement conversion device according to the present invention and an imaging device using the same will be described with reference to the drawings. In the following description, an example will be described in which the radiation is infrared light and the readout light is visible light (monochromatic light, mixed light of a plurality of types of single colors, or white light). Or other various kinds of radiation, or the readout light may be light other than visible light.

(First Embodiment) First, the first embodiment of the present invention will be described.
An optical readout type radiation-to-displacement converter according to the embodiment will be described with reference to FIGS. 1 and 2. FIG.

FIG. 1 is a diagram showing an optical readout type radiation-to-displacement converter according to a first embodiment of the present invention.
FIG. 1A is an enlarged view schematically showing a cross section of the entire device, and FIG. 1B is a diagram schematically showing a cross section of a unit pixel (unit element). FIG. 2 shows the optical readout radiation shown in FIG.
FIG. 4 is a schematic perspective view of the displacement conversion device, with the container 20 removed, as viewed from the read light j incident side (the lower side in the figure).

The radiation-to-displacement conversion device according to the present embodiment includes a base 1 and a supported part 3 supported on the base 1 in a state of being floated via the legs 2. In this embodiment, infrared rays i as radiation to be detected enter from the upper side in FIG. 1 and readout light j enters from the lower side in FIG.

In the present embodiment, the base 1 is composed of a thin film member 4 having a light transmitting property with respect to the readout light j,
And a reinforcing member 6 lining a predetermined area other than an area corresponding to a window 5 described later. For example,
Silicon nitride can be used as the material of the thin film member 4, and silicon single crystal can be used as the material of the reinforcing member 5. The silicon nitride film 7 used for forming the reinforcing member 6 is formed at a lower end portion of the reinforcing member 6. Of course, this silicon nitride film 7 may be removed.

The supported portion 3 is composed of two films 8 and 9 which are overlapped with each other. These films 8 and 9 are infrared absorption portions that receive the infrared light i and convert it to heat. The film 8 and the film 9 are made of different substances having different expansion coefficients, and form a so-called thermal bimorph structure. Therefore, in the present embodiment, the films 8 and 9 constitute a displacement portion that displaces with respect to the base 1 in accordance with heat generated in the films 8 and 9 as an infrared absorbing portion. As described later, since the films 8 and 9 constitute a cantilever, when the expansion coefficient of the lower film 9 is larger than the expansion coefficient of the upper film 8, as shown in FIG. It is curved upward and inclined. Conversely, the lower membrane 9
May be smaller than the expansion coefficient of the upper film 8, and in this case, the heat will cause the film to curve downward and tilt. In the present embodiment, the lower film 9,
In particular, the front end side region constitutes a total reflection mirror as a reflection portion for reflecting the readout light j. In addition, for example,
Silicon nitride or the like can be used as the material of the film 8,
Aluminum or the like can be used as the material of the film 9.

The support leg 2 is composed of a portion in which the films 8 and 9 extend so as to be bent from the portion of the portion 3 to be supported, and is fixed to the thin film member 4. As a result, the films 8, 9 in the portion to be supported 3 constitute a cantilever. However, for example, a diaphragm may be configured.

In the present embodiment, an infrared reflecting film 10 made of aluminum or the like is formed on the upper surface of the thin film member 4 facing the substantially central region of the portion constituting the supported portion 3 of the films 8 and 9. ing. The infrared reflecting film 10 and the film 8,
9 is an odd number of n, and the center wavelength of the incident infrared light i is λ.
_0, is set to be substantially n [lambda _0/4. That is, a so-called optical cavity structure that causes interference between the incident infrared ray i and the reflected infrared ray between the infrared reflecting film 10 and the films 8 and 9 is formed. Incident infrared i
Is partially absorbed by the films 8 and 9, and the rest passes through the films 8 and 9, is reflected on the upper surface of the reflection film 10, and enters the films 8 and 9 again. For this reason, an interference phenomenon occurs between the films 8, 9 and the reflection film 10, and the distance between the two is approximately an odd multiple of 1/4 of the center wavelength of the incident infrared light. Infrared absorption is maximized, and the absorptivity of infrared rays in the films 8 and 9 is further increased.

Further, in the present embodiment, a half mirror portion 11 made of a metal thin film or the like that transmits only a part of the received read light j is provided on the upper surface of the thin film member 4 facing the front end region of the film 9. Is formed. The tip side region (reflection portion) of the film 9 and the half mirror portion 11 receive the readout light j, and read out the received readout light j by changing the received readout light j into interference light having an interference state corresponding to the displacement of the displacement portion. Light j
And interference means for emitting light in the direction opposite to the incident direction. In the present embodiment, it is a region in the thin film member 4 having translucency, and is a region on the tip side of the film 9 (reflection portion).
The area corresponding to the area where the half mirror section 11 and the half mirror section 11 face each other is a window 5 through which the interference means receives the read light j and emits the interference light. As mentioned above, this window 5
Is not provided with a reinforcing member 6.

[0058] As shown in FIG. 1 (b), when the reading light j is incident on the half mirror 11, the reflected light portion of the read beam j is reflected by the half mirror unit 11 j _1, and the half mirror unit The rest of the reading light j that has entered the mirror 11 passes through the half mirror 11 and is reflected by the film 9 as a total reflection mirror, and then enters the half mirror 11 again from above. Part of the read light again incident from the upper surface to the half mirror unit 11 is transmitted light j ₂ passes through the half mirror 11. There is an optical path length difference between the transmitted light j ₂ and the reflected light j ₁ corresponding to twice the distance d between the half mirror portion 11 and the film 9. Therefore, interference occurs in response to the optical path length difference between the reflected light j ₁ and transmitted light j _2, the reflected light j ₁ and transmitted light j ₂ is corresponding to the optical path length difference (and therefore, films 8 and 9 The light is emitted from the half mirror unit 11 as interference light having an interference intensity (corresponding to the displacement of the light source). Since the interference intensity of the interference light and the intensity of the transmitted light j ₂ and the intensity of the reflected light j ₁ is strongest when equal,
The reflectance of the half mirror section 11 is set to approximately 1/3, for example, about 3
It is desirable to make it 3%.

In the present embodiment, the distance (gap) d between the front end region of the film 9 as the reflecting portion and the half mirror portion 11 is determined by the heat generated by the films 8 and 9 as the radiation absorbing portion. Is set so that the intensity of the interference light decreases as the value increases. Specifically, the initially set distance d may be set, for example, as shown in FIG. 4 or FIG. That is, when the expansion coefficient of the lower film 9 is larger than the expansion coefficient of the upper film 8 and the films 8 and 9 are curved upward by heat (the distance d increases), for example, the initial value of the distance d is increased. The set value (the distance when the incident infrared ray i to be detected is not incident) may be set to one of the distances d1 as shown in FIG. Conversely, the lower membrane 9
Is smaller than the expansion coefficient of the upper membrane 8,
In the case where 9 is bent downward by heat (distance d becomes smaller), for example, the initial setting value of the distance d may be set to any one of distances d2 as shown in FIG. FIGS. 4 and 5 are diagrams showing the relationship between the distance d and the intensity of the interference light and the initial set distances d1 and d2, respectively.

When the distance d is set in this manner, the displacement of the films 8 and 9 is increased even if the incident amount of the infrared ray i is the same, and the detection sensitivity of the infrared ray i is further improved. That is, when the intensity of the interference light decreases, the readout light j incident on the front end side region of the film 9 as the interference means and the half mirror portion 11 by the decrease corresponds to the interference means (the film as a reflection portion from the half mirror portion 11). 9 is larger in the amount of absorption, that is, the amount of heat generation), and is converted into heat. Therefore, in the present embodiment, since the distance d is set as described above, when the amount of radiation received by the films 8 and 9 increases and the heat generated by the films 8 and 9 increases, Accordingly, the displacement of the films 8, 9 reduces the intensity of the interference light, increases the amount of the read light j absorbed by the film 9, increases the heat generated in the film 9, and increases the heat of the films 8, 9 Is further increased, and the films 8 and 9 are further displaced.
In this manner, the heat generated by the absorption of the read light by the interference means (particularly, the front end region of the film 9) is skillfully used, and the film 8,
9 is increased, and as a result, the detection sensitivity of infrared rays i is further improved.

As can be seen from the above description, in the present embodiment, the film 8 also serves as a part of the displacement part and a part of the infrared absorbing part, and the film 9 serves as another part of the displacement part and the interference means. The reading light reflection part is also used. Therefore, the structure is simple and inexpensive. Needless to say, the displacement section, the infrared absorption section, and the readout light reflection section may be made of independent materials.

In this embodiment, the films 8 and 9, the infrared reflection film 10, and the half mirror unit 11 are used as unit pixels (unit elements), and the pixels are two-dimensionally arranged on the base 1. However, if necessary, the pixels may be arranged one-dimensionally on the base 1, or if only the intensity of radiation is to be detected, only a single pixel may be arranged on the base 1. You may.

In this embodiment, FIGS. 1 and 2
As shown in FIG. 5, a reflection surface 6a that is inclined with respect to the incident direction of the readout light j is formed in a predetermined region of the base 1 except for the window 5. In the present embodiment, the reflection surface 6a is formed around the window 5 so as to form a trapezoidal space (a mortar-shaped space) extending from the window 5 to the incident side of the readout light j with the window 5 as the bottom. Said reinforcing member 6
Is formed on the surface. In the present embodiment, the reflecting surface 6a makes most of the light other than the readout light that is received by the interference unit and converted into the interference light out of the readout light j illuminated, The deflecting / reflecting means constitutes a deflecting / reflecting means for deflecting and reflecting in a direction inclined with respect to the direction emitted from the interference means.

In this embodiment, since the reflecting surface 6a is configured as described above, one independent window 5 is formed for each unit element. However,
For example, as shown in FIG. 3, the reflection surface 6 a is formed such that the window 5 forms a trapezoidal space (striped space) extending toward the incident side of the readout light j with the window 5 as the bottom.
May be formed on the reinforcing member 6 on both sides. In this example, as shown in FIG. 3, the windows 5 of the unit pixels in each column are arranged in a line.

By the way, of the illuminated read light j, the interference light emitted by the interference means in the direction opposite to the incident direction of the read light is the signal light. When light (that is, noise light) is reflected in the same direction as the signal light and mixes with the signal light,
The so-called S / N is reduced. In this regard, according to the present embodiment, most of the irradiated read light j other than the read light that is received by the interference means and converted into the interference light is shown in FIG. 1B. As described above, since the interference light is deflected and reflected by the reflection surface 6a in a direction inclined with respect to the direction (downward in FIG. 1) emitted from the interference means, noise light is mixed with signal light. And S / N is improved. Alternatively, the read light j
It is conceivable to provide an anti-reflection film for preventing reflection of light other than the interference light emitted in the direction opposite to the incident direction of the readout light j by the interference means, even in this case,
S / N is improved without noise light being mixed with signal light. However, in this case, the noise light is absorbed by the anti-reflection film to generate heat, and the heat is transmitted to the films 8 and 9, and the heat displaces the films 8 and 9. .
Therefore, in this case, the noise light of the readout light j is absorbed by the antireflection film and the films 8 and 9 are displaced by the heat transmitted to the films 8 and 9 and the detection accuracy of the infrared light i is reduced. Resulting in. In this regard, according to the present embodiment,
Since the noise light of the read light j is reflected by the reflection surface 6a, the noise light is not absorbed to generate heat. For this reason, according to the present embodiment, since only heat due to incident radiation is detected, detection accuracy is improved. As described above, according to the present embodiment, it is possible to simultaneously improve the S / N and the detection accuracy.

In the present embodiment, the structure composed of the above-described components 1 to 11 is housed in the container 20,
The inside of the container 20 is in a vacuum state. this is,
This is for thermally isolating the structure from the outside and preventing the films 8, 9 from losing heat immediately after absorbing the infrared rays i. The upper part of the container 20 is configured to transmit infrared rays i, and the lower part of the container 20 is configured to transmit reading light j.

Next, the optical readout type radiation-to-displacement converter shown in FIGS. 1 and 2 can be manufactured using, for example, a semiconductor manufacturing process.
This will be described with reference to FIGS. 6 and 7 are schematic cross-sectional views showing each step of the manufacturing method, and show cross sections corresponding to FIG. 6 (b) to FIG.
FIG. 6D corresponds to an enlarged view of the portion A in FIG.

First, a semiconductor substrate having a thickness of 250 μm is used.
Pixel row formation area in each chip formation area of silicon single crystal substrate 30 having m, (100) plane orientation (pixel row formation area for one chip (one optical readout radiation-displacement converter) is about 20 μm) (FIG. 6A), that is, although not shown in the drawing,
The substrate 30 is thermally oxidized to protect both surfaces of the substrate 30 with thermal oxide films, respectively, and the thermal oxide film on the back surface of the substrate 30 is photoetched to expose the silicon surface in the pixel column formation area (image area). By subjecting the substrate 30 to wet or dry etching, the thickness of the substrate 30 in the pixel column formation region is reduced to about 20 μm.
The remaining thermal oxide film on both sides is removed (FIG. 6A). The step of thinning the formation region of the pixel columns on the substrate 30 is performed to narrow the pixel pitch to, for example, about 20 μm to 50 μm in relation to the step shown in FIG. This is unnecessary when the pixel pitch is relatively large.

Next, the substrate 30 in the state shown in FIG. 6A is thermally oxidized again, and both surfaces of the substrate 30 are protected by thermal oxide films 31 and 32, respectively (FIG. 6B).

Next, the thermal oxide film 31 on the upper surface is photo-etched and patterned into a stripe shape having a width of 10 μm. Thereafter, the substrate is washed with an aqueous solution of potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMA).
H) Immerse in an etching solution for silicon such as aqueous solution,
Using the striped thermal oxide film pattern 31 as a protective film, the exposed portion of the substrate 30 is anisotropically etched into a trapezoid to form a groove 33 having a depth of about 2.5 μm (FIG. 6).
(C)).

Here, by forming such a groove 33, a silicon nitride film 34 (corresponding to the thin film member 4 in FIG. 1) described later is formed on a metal film 36 (infrared reflecting film 10 in FIG. 1). The reason why a step is formed between a portion where a metal thin film 37 (corresponding to the half mirror portion 11 in FIG. 1) and a portion where a metal thin film 37 described later (corresponding to the half mirror portion 11 in FIG. 1) is formed will be briefly described. As described above, the infrared reflective film 10 for the incident infrared i
Since the so-called optical cavity structure that causes interference between the component reflected by the infrared ray and the component reflected by the films 8 and 9 of the incident infrared ray i is adopted, the infrared reflecting film 1
Assuming that the wavelength of the infrared ray i to be detected is 8 to 12 μm, for example, the interval between 0 and the films 8 and 9 is, for example, about 1/4 of 2
It is preferable to set the thickness to ３3 μm. On the other hand, as described above, the distance (gap) d between the front end side region of the film 9 as the reflecting portion and the half mirror portion 11 is set as shown in FIGS. In the present embodiment, when the temperature of the films 8 and 9 increases, the gap interval d increases, so that the gap interval may be set as shown in FIG. For example, if the wavelength of the reading light j is about 5000 angstroms, the distance d is preferably set to about 1000 angstroms (that is, about 0.1 μm). However, the gap interval may be obtained by adding an integral multiple of half the wavelength of the readout light to the gap interval. As described above, in the region for receiving the infrared light i and the region for emitting the readout light j, the distance between the films 8, 9 and the infrared reflection film 10 and the distance between the films 8, 9 and the half mirror unit 11 are as follows. Will be different. In order to realize such a situation, a step may be formed in the films 8 and 9, but compared with that case, the thin film member 4 (ie,
The production becomes easier when steps are formed in the silicon nitride film 34). Thus, in the present embodiment, the above-described groove 33 is formed.

Next, the thermal oxide films 31 on both sides of the substrate 30,
After removing 32, silicon nitride films 34 and 35 having a thickness of 5 μm are formed on both surfaces of substrate 30 by LP-CVD or the like (FIG. 6D). The silicon nitride film 34 corresponds to the thin film member 4, and the silicon nitride film 35 corresponds to the silicon nitride film 7.

Thereafter, the silicon nitride film 35 on the back surface of the substrate in the state shown in FIG. 6D is formed in a lattice shape by photoetching so as to conform to the shape of the silicon nitride film 7 (to obtain a structure as shown in FIG. 3). (FIG. 6 (e)).

Next, the substrate in the state shown in FIG. 6E is immersed in an etching solution for silicon such as an aqueous solution of potassium hydroxide (KOH) or an aqueous solution of tetramethylammonium hydroxide (TMAH), and is patterned into the lattice shape. Using the silicon nitride film 35 as a protective film, the exposed portion of the substrate 30 is anisotropically etched into a truncated pyramid shape to form a trench 41 having a depth of about 20 μm (FIG. 7).
(A)). Thereby, the remaining portion of the substrate 30 corresponds to the reinforcing member 6. In addition, (10
0) Since a plane orientation is used, the angle formed by the inclined surface 30a (corresponding to the reflection surface 6a) of the truncated pyramid-shaped trench 41 with respect to the substrate surface is 54.74, as is well known.
°.

After that, the grooves 33 are lifted off by the lift-off method.
A metal film 36 (for example, Al having a thickness of 5000 angstroms) corresponding to the infrared reflection film 10 is formed on the silicon nitride film 34 formed in the portion shown in FIG. A metal thin film (for example, having a thickness of 50 nm) corresponding to the half mirror portion 11 is formed on the silicon nitride film 34 formed in a portion other than the groove 33.
Angstrom Al) 37 is formed (FIG. 7).
(B)).

Next, a resist film 38 as a sacrificial layer is applied to the upper surface of the substrate in the state shown in FIG. 7B, and the resist film 38 is patterned into a stripe by lithography (FIG. 7C). .

Next, an aluminum thin film 39 (corresponding to the film 9) having a thickness of 0.1 μm and a thickness of 0.1 μm were formed at predetermined positions on the upper surface of the substrate in the state shown in FIG.
And a silicon nitride thin film 40 (corresponding to the film 8). Further, although not shown, dicing is performed to divide each chip, and finally, a resist film 3 as a sacrificial layer is formed.
8 is removed by the ashing method (FIG. 7D).

Finally, the structure in the state shown in FIG. 7D is accommodated in the container 20 and the inside is sealed in a vacuum.
Thus, the optical readout radiation-displacement converter shown in FIGS. 1 and 2 is completed.

According to the optical readout radiation-displacement converter according to the first embodiment shown in FIGS. 1 and 2 described above, infrared rays i are incident from above in FIG. The infrared rays i are absorbed by the films 8 and 9 also serving as infrared ray absorbing parts and converted into heat. At this time, as described above, the films 8, 9
In addition, the optical absorptivity of the optical cavity structure including the infrared reflective film 10 is enhanced. FIG. 1 (b)
As shown in (1), the films 8, 9 also serving as displacement parts are curved upward and inclined in accordance with the heat generated in the films 8, 9. That is, the incident infrared rays i are converted into displacements of the films 8, 9 according to the amount. On the other hand, a readout optical system, which will be described later, causes a readout light j of visible light to enter from below in FIG. The half mirror portion 11 as the interference means and the tip side region of the film 9 change the received readout light into interference light having an interference state corresponding to the displacement of the films 8 and 9 in the direction opposite to the incident direction of the readout light j. Since the light is emitted, the infrared light i irradiated on the films 8 and 9 is converted into a change in the interference state of the interference light. Therefore, as described later, the infrared ray i can be detected based on the emitted interference light. At this time, since displacement detection by interference light can be performed with high sensitivity, according to the present embodiment, infrared rays can be detected with high sensitivity. Further, in the present embodiment, the infrared light is not converted into a resistance value (electric signal) through heat, but is converted into a change in interference light due to readout light through heat and displacement, instead of being converted into a resistance value (electric signal). There is no need to supply a current to the supported portion 3, and no self-heating occurs in the supported portion 3. Therefore, according to the present embodiment, since heat is detected only by the incident infrared rays, the S / N is improved and the detection accuracy is improved. Needless to say, in the present embodiment, the cooler that was required in the quantum infrared detector is not required. Further, in the present embodiment, since infrared light is not read out as an electric signal, a readout circuit for a weak electric signal which is necessary in a conventional thermal infrared detector becomes unnecessary.

Further, according to the present embodiment, as described above, the distance (gap) d between the front end side region of the film 9 as the reflecting portion and the half mirror portion 11 is set to the above-mentioned predetermined distance. Therefore, the heat generated by the absorption of the readout light by the interference means (particularly, the front end region of the film 9) is skillfully used, and the displacement of the films 8, 9 is increased. As a result, the infrared rays i Is further improved.

Further, according to the present embodiment, as described above, of the read light j irradiated, the light (noise light) other than the read light that is received by the interference means and converted into the interference light is converted. Most of the light is deflected and emitted in a direction inclined with respect to the direction in which the interference light is emitted by the reflection surface 6a as a deflection / reflection means, so that an improvement in S / N and an improvement in detection accuracy are simultaneously achieved. can do.

Here, a numerical example of how much output is obtained in the present embodiment will be described.

The incident infrared light i is absorbed by the films 8 and 9 and converted into heat as described above. At this time, as described above, the infrared reflective film 10 increases the infrared absorptance by the principle of the optical cavity.

Here, η is the infrared absorption coefficient of the whole of the films 8 and 9 (hereinafter referred to as “bimorph”), and t is the infrared lens (the lens 50 in FIG. 8 described later) and the window of the upper part of the container 20. The transmission coefficient, Ad is the effective area of the bimorph receiving infrared rays, L is the distance from the heat source of the bimorph, As
Is the area of the heat source, ε is the radiation coefficient of the heat source, and σ is the Stefan-Boltzmann constant (5.67 × 10 ⁻¹² W · cm ^−2.
K ^-4 ), where Ts is the temperature of the heat source, and Tr is the temperature of the bimorph itself, the amount of infrared light P from the heat source absorbed by the bimorph of one element (pixel) per unit time is expressed by the following equation 1. .

[0085]

(Equation 1)

Here, t = 0.7, Ad = 6.2 × 10
^-4 cm ² , η = 0.9, L = 15 cm, As = 90c
m, Tr = 300K, ε = 0.43, temperature Ts =
The amount P of infrared light which is absorbed by a bimorph of one element per unit time of infrared light from a heat source of 400K is 0.1 mW.

The temperature of the object to be measured (heat source) is 400K.
, The energy change of the infrared light absorbed by the bimorph of one element is about 1.4 μW by the same calculation.

The infrared energy absorbed by the bimorph raises the temperature of the bimorph. Thereby, a temperature gradient is generated between the bimorph (membrane 8, 9) and the thin film member 4 supported by the bimorph.

Here, the temperature change ΔT from the supporting point of the bimorph (where the films 8 and 9 are fixed to the thin film member 4)
Is expressed as the following equation 2 as a function of the distance x from the free end of the bimorph.

[0090]

(Equation 2)

Here, 1 is the length of the bimorph (support 2
, P is the amount of heat absorbed by the bimorph per unit time, w is the width of the bimorph, λ1 and λ2 are the thermal conductivities of the materials of the films 9 and 8 constituting the bimorph, t1 and t2 Is the thickness of each of the films 9 and 8 constituting the bimorph. Here, the material of the film 9 constituting the bimorph is aluminum, the material of the film 8 is silicon nitride, 1 = w = 30 μm, P = 1 μW, λ1 = 237
W · m ⁻¹ · K ⁻¹ , λ2 = 32 W · m ⁻¹ · K ⁻¹ , t1 = t
If 2 = 0.1 μm, the temperature change at the tip of the bimorph is 1.64K. When the temperature of the device under test is 400K
, The temperature change at the tip of the bimorph is 0.0223K.

Since the bimorph is made of two kinds of substances having different thermal expansion coefficients, when the temperature of the bimorph rises, the bimorph is deformed upward or downward. In order to estimate the amount of displacement, the radius of curvature r of the bimorph at that time is first determined. The radius of curvature of the bimorph when the bimorph rises by a certain temperature T is given by the following equation (3).

[0093]

(Equation 3)

Here, E1 and E2 are Young's moduli of aluminum and silicon nitride, and γ1 and γ2 are thermal expansion coefficients of aluminum and silicon nitride. Here, E1 = 0.8 ×
10 ¹¹ Nm ⁻² , E2 = 1.8 × 10 ¹¹ Nm ⁻² , γ1 = 2
3.9 × 10 ⁻⁶ K ⁻¹ , γ2 = 3 × 10 ⁻⁶ K ⁻¹ , t1 = t
If 2 = 0.1 μm, the temperature of the measured object is 400K
In this case, the radius of curvature of the bimorph bending becomes 7.46 nm, and the change in the radius of curvature of the bimorph bending when the measured object changes from 400 K to 401 K is 550 nm. The magnitude of the deflection of the free end with respect to the fixed end of the structure having a certain curvature r is expressed by the following equation when r is sufficiently larger than the length L of the structure.

[0095]

(Equation 4)

Here, if L = 30 μm, the deflection of the bimorph when the temperature of the measured object is 400 K is 60.2.
nm, and the change in the deflection of the bimorph when the temperature of the device under test increases from 400 K to 401 K is 0.82 nm.
Becomes

Next, consider the case where the deflection of the bimorph is read out by the optical interference method. As reading light,
One semiconductor laser having a wavelength of 680 nm and an output of 30 mW is used. The size of the whole optical readout radiation-displacement converter (excluding the container 20) is 20 m on each side.
Assuming that the size of the window 5 into which the readout light is incident is a square having a side of 10 μm, a semiconductor laser incident on the half mirror portion 11 of one pixel and the cavity formed by the tip end region of the film 9 Power is about 120n
W. Here, the output (the output of the interference light) that interferes with the cavity and is reflected out of the cavity is
It is given by Equation 5 below.

[0098]

(Equation 5)

Here, I ₀ is the amount of light incident on the cavity, d is the distance between the cavities (the distance between the half mirror portion 11 and the film 9), and λ is the wavelength of the read light. Here, I ₀ = 120 nW, λ = 680 nm, and the cavity interval d when the object to be measured is 400K is 255 nm.
In this case, the intensity of the light reflected from the cavity is half that of the incident light, that is, 60 nW. Next, when the measured object is 4
When the temperature rises to 01K, the bimorph deflection becomes 0.8
The intensity of the reflected light from the cavity when increasing by 2 nm decreases by about 1 nW. This decrease in the intensity of the reflected light from the 1 nW cavity is detected by a visible light imaging sensor such as a CCD. The decrease in the intensity of the reflected light from the cavity is mostly absorbed as heat by the aluminum thin film 9 on the lower surface of the bimorph while repeating multiple reflections in the cavity, and further deforms the bimorph. That is,
When the temperature from the measured object rises, the light confined in the cavity becomes heat and further raises the temperature of the bimorph. As described above, this increases the detection sensitivity.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
The imaging apparatus according to the embodiment will be described with reference to FIG. FIG. 8 is a schematic configuration diagram showing the imaging device according to the present embodiment.

The imaging apparatus according to the present embodiment is an optical readout type radiation-to-displacement conversion apparatus shown in FIG. 1 according to the first embodiment (indicated by reference numeral 100 in FIG. 8,
The vertical and horizontal directions in FIG. 1 and the vertical and horizontal directions in FIG. ), An infrared imaging lens 50 for condensing the infrared light i and forming an infrared image on the surface of the conversion device 100 where the films 8 and 9 are distributed, and the conversion device 100
The half mirror portion 11 of each of the elements (pixels) is irradiated with the readout light through the window 5 in the direction opposite to the incident direction of the readout light through the window 5 from the half mirror portion 11 of each of the elements. A readout optical system that forms an optical image corresponding to the displacement of the films 8 and 9 as displacement portions of the respective elements based on the emitted interference light, and a two-dimensional CCD 60 as an imaging unit that captures the optical image. , Is provided.

More specifically, the imaging apparatus according to the present embodiment includes a semiconductor laser light source 71 having a wavelength of 680 nm and an output of 30 mW, a collimating lens 72, an anamorphic prism 73, a polarizing beam splitter 74, a quarter-wave plate 75 , Lens 76, and these constitute the readout optical system.

In the present embodiment, infrared rays i are condensed by the imaging lens 50 and an infrared image is formed on the surface of the converter 100 where the films 8 and 9 are distributed. As a result, the films 8 and 9 of each pixel are displaced in accordance with the amount of incident infrared light on the films 8 and 9 of each pixel of the conversion device 100.

On the other hand, since the laser light emitted from the laser light source 71 has an elliptical intensity distribution, the collimating lens 7
After being converted into parallel light by 2, the light is corrected into a circular intensity distribution by an anamorphic prism 73. Since the laser light whose intensity distribution has been corrected is linearly polarized light,
After being reflected by the polarizing beam splitter 74,
By passing through the four-wavelength plate 75, the light becomes circularly polarized light, and this circularly polarized light is incident on the conversion device 100 from the back surface as readout light. This circularly polarized light uniformly illuminates the back surface of the conversion device 100.

As described with respect to the first embodiment, the light 8 of the readout light of the circularly polarized light which is incident on the half mirror portion 11 of each pixel from the window 5 of each pixel as described above. , 9 are emitted from the half mirror section 11 through the window 5 in a direction opposite to the incident direction of the readout light (that is, downward in FIG. 8). This interference light is again transmitted to the 波長 wavelength plate 7.
5, the light is changed from circularly polarized light to linearly polarized light.
Since the polarization direction at this time is rotated by 90 ° with respect to the polarization direction at the time of incidence, it passes through the polarization beam splitter 74. Thereafter, the interference light transmitted through the polarization beam splitter 74 is converted from light from one pixel of the conversion device 100 by the CCD 6.
After the size is adjusted by the lens 76 so as to be incident on one pixel of 0, the light is incident on the CCD 60. That is, an optical image is formed on the CCD 60 by the interference light, and the optical image is captured by the CCD 60. Thus, the incident infrared image is converted into a visible image, and the visible image is captured.

Here, of the readout light of the circularly polarized light, the light incident on portions other than the window 5 of each pixel is as follows.
explain. One representative ray of such light is
This is indicated by a dotted line in FIG. The light beam shown by the dotted line is incident on the above-mentioned reflecting surface 6a (corresponding to the above-described inclined surface 30a of the quadrangular pyramid-shaped trench 41 in FIG. 7) formed on the back surface of the conversion device 100. As described above, the angle formed by the reflection surface 6a with respect to the substrate surface is 54.74.
Since the normal of the substrate surface is in the incident direction of the readout light of the circularly polarized light, the light ray indicated by the dotted line again enters the reflecting surface 6a opposite to the reflecting surface 6a that first entered. Will be reflected. The angle formed by the reflected light with respect to the substrate surface is 109.48 °). Since this reflected light becomes the background of the interference light, C
It is desirable that the light does not enter the CD 60. Therefore, when the conversion device 100 is a square having a side of 20 mm, the conversion device 1
By setting the distance between 00 and the reading optical system at least about 57 mm, the reflected light does not enter the reading optical system.

In this embodiment, the optical image is
Although the image is captured by the CD 60, the optical image may be observed with the naked eye.

In the present embodiment, a monochromatic light source is used as the light source 71, but a white light source or a light source that emits two types of monochromatic light having different wavelengths may be used.

The configuration of the readout optical system is not limited to the configuration described above.

(Third Embodiment) Next, the third embodiment of the present invention will be described.
An optical readout type radiation-to-displacement converter according to the embodiment will be described with reference to FIG.

FIG. 9 is a diagram showing an optical readout type radiation-to-displacement converter according to a third embodiment of the present invention.
(A) is a diagram schematically showing a cross section of the entire device, and FIG.
(B) is an enlarged view schematically showing a cross section of the unit pixel (unit element). In FIG. 9, the same or corresponding elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

The difference between the converter according to the present embodiment and the converter according to the first embodiment shown in FIG. 1 is that, in the converter shown in FIG.
a and the silicon nitride film 7 are formed, but in the present embodiment, the inclined reflecting surface 6 a and the silicon nitride film 7 are not formed on the reinforcing member 6, and the reading light of the reinforcing member 6 is incident on the reinforcing member 6. The only difference is that the reflective diffraction grating 80 is formed on the side surface (the lower surface in FIG. 9).

In this embodiment, the reflection type diffraction grating 8
0 denotes a silicon nitride film 81 formed on the lower surface of the reinforcing member 6 according to a predetermined lattice pattern, and a portion on the lower surface of the reinforcing member 6 where the silicon nitride film 81 is not formed and on the silicon nitride film 81. And a metal film 82 of gold or the like as a formed reflective film.

The step between the metal film 82 on the reinforcing member 6 and the metal film 82 on the silicon nitride film 81 is, for example, １ ／ of the wavelength λ of the reading light. The lattice spacing, that is, the spacing between the silicon nitride films 81 is set to twice (for example, about 1 μm) the wavelength λ of the reading light.

Since the step is λ / 4, considering the read light reflected in the direction perpendicular to the surface of the grating (ie, downward in FIG. 9), the metal film 8 on the reinforcing member 6
The optical path length difference between the light reflected at 2 and the light reflected at the metal film 82 on the silicon nitride film 81 is λ / 2, and the phase condition does not match. Therefore, as shown in FIG. 9B, the readout light j is diffracted in the direction of the first-order diffraction in which the optical path length difference is λ. At this time, since the lattice spacing is 2λ, 1
The diffraction angle θ of the next-order diffracted light is 30 °.

Since the diffracted light of the read light becomes the background of the interference light which is the signal light, when the conversion device according to the present embodiment is a square having a side of 20 mm, the conversion device and the read optical system are connected. By separating the light by about 35 mm or more, the diffracted light does not enter the readout optical system.

As described above, in the present embodiment, of the read light to be irradiated, the light other than the read light which is received by the interference means (the half mirror section 11 and the front end region of the film 9) and converted into the interference light is received. As a deflecting / reflecting means for deflecting and reflecting most of the light in a direction inclined with respect to the direction in which the interference light is emitted from the interference means (downward in FIG. 9),
A reflection type diffraction grating 80 is employed.

According to this embodiment, the same advantages as those of the first embodiment shown in FIG. 1 can be obtained.

In the imaging apparatus shown in FIG. 8 described above, the light-reading radiation-displacement converter 100 is
It goes without saying that the conversion device according to the present embodiment can be used.

Here, an example of a method of manufacturing the converter according to the present embodiment will be described with reference to FIG. FIG. 10 is a schematic cross-sectional view showing each step of the manufacturing method, and shows a cross section corresponding to FIG. 10, the same or corresponding elements as those in FIGS. 6 and 7 described above are denoted by the same reference numerals, and description thereof will be omitted.

First, although not shown in FIG. 10, the manufacturing method of the converter shown in FIG.
The same step as the step shown in FIG.

Next, the silicon nitride film 35 on the back surface of the substrate in the state shown in FIG. 6D is patterned according to the shape of the silicon nitride film 81 by photoetching (FIG. 10A). In this example, the silicon nitride film 35 corresponds to the silicon nitride film 81.

Thereafter, a gold film 90 corresponding to the metal film 82 is formed on the lower surface of the substrate in the state shown in FIG.
Then, a part of the film 90 and a part of the substrate 30 are removed by dry etching (FIG. 10B).

Next, as in the steps described with reference to FIGS. 7B to 7D, the steps of forming the metal film 36 and the metal thin film 37, and forming the resist film 38 as a sacrificial layer , An aluminum thin film 39 and a silicon nitride thin film 40, a dicing process, and a resist film 38 removing process are sequentially performed (FIG. 10C).

Finally, the structure in the state shown in FIG. 10C is accommodated in the container 20 and the inside is sealed in a vacuum. Thus, the optical readout radiation-displacement converter shown in FIG. 9 is completed.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.
An optical readout type radiation-to-displacement converter according to the embodiment will be described with reference to FIG.

FIG. 11 is a diagram schematically showing a cross section of a unit pixel (unit element) of an optical readout type radiation-to-displacement converter according to a fourth embodiment of the present invention. In FIG.
Elements that are the same as or correspond to the elements in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

The difference between the converter according to the present embodiment and the converter according to the first embodiment shown in FIG. 1 is that, in the converter shown in FIG.
a and the silicon nitride film 7 are formed, whereas in the present embodiment, the inclined reflecting surface 6 a and the silicon nitride film 7 are not formed on the reinforcing member 6, The only difference is that the microprism array 85 is provided or formed on the side surface (the lower surface in FIG. 9). The microprism array 85 may be formed on the lower surface of the reinforcing member 6 by a known method, or a separately prepared one may be provided on the lower surface of the reinforcing member 6 by bonding.

As described above, in this embodiment, of the read light to be irradiated, other than the read light which is received by the interference means (the half mirror section 11 and the tip side region of the film 9) and converted into the interference light. A microprism array 85 is employed as a deflecting / reflecting means for deflecting and reflecting most of the light in a direction inclined with respect to the direction in which the interference light is emitted from the interference means (downward in FIG. 11). But
According to this embodiment, the same advantages as those of the above-described first embodiment shown in FIG. 1 can be obtained.

In the imaging device shown in FIG. 8 described above, the light-reading radiation-displacement converter 100 is
It goes without saying that the conversion device according to the present embodiment can be used.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

[0132]

As described above, according to the present invention,
The radiation detection accuracy and sensitivity can be improved without using a cooler.

Further, according to the present invention, when the deflecting / reflecting means is employed, further improvement in S / N and further improvement in detection accuracy can be achieved at the same time.

Further, according to the present invention, when the distance between the reflecting section and the half mirror section is specially set, the radiation detection sensitivity can be further improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical readout type radiation-displacement conversion device according to a first embodiment of the present invention. FIG. 1 (a) is a diagram schematically showing a cross section of the entire device, and FIG. () Is an enlarged view schematically showing a cross section of the unit pixel.

FIG. 2 is a schematic perspective view of the optical readout radiation-displacement converter shown in FIG. 1 with a container removed and viewed from a readout light incident side.

FIG. 3 is a diagram showing a modification of the optical readout type radiation-displacement converter shown in FIG. 1, and is a schematic perspective view corresponding to FIG. 2;

FIG. 4 is a diagram illustrating an example of a relationship between a distance between a reflection unit and a half mirror unit and the intensity of interference light, and an example of an initial setting value of the distance.

FIG. 5 is a diagram illustrating another example of a relationship between a distance between a reflection unit and a half mirror unit and the intensity of interference light, and an initial setting value of the distance.

FIG. 6 is a diagram showing an example of a manufacturing process of the optical readout type radiation-displacement converter shown in FIG.

FIG. 7 is a view showing a manufacturing process of the optical readout type radiation-displacement conversion device shown in FIG. 1, which is a manufacturing process subsequent to FIG. 6;

FIG. 8 is a schematic configuration diagram illustrating an imaging device according to a second embodiment of the present invention.

9A and 9B are diagrams showing an optical readout type radiation-to-displacement converter according to a third embodiment of the present invention. FIG. 9A is a diagram schematically showing a cross section of the entire device, and FIG. () Is an enlarged view schematically showing a cross section of the unit pixel.

FIG. 10 is a diagram illustrating an example of a manufacturing process of the optical readout type radiation-displacement conversion device illustrated in FIG. 9;

FIG. 11 is a diagram schematically showing a cross section of a unit pixel of an optical readout type radiation-to-displacement converter according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base 2 Support leg 3 Supported part 4 Thin film member 5 Window 6 Reinforcement member 6a Reflection surface 8,9 film 10 Infrared reflection film 11 Half mirror part 20 Container 50 Infrared imaging lens 60 CCD 71 Semiconductor laser light source 72 Collimating lens 73 Anamorphic prism 74 Polarizing beam splitter 75 Quarter-wave plate 76 Lens 80 Reflective diffraction grating 81 Silicon nitride film 82 Reflective film 85 Microprism array 100 Optical readout radiation-displacement converter

Claims (12)

[Claims] 1. A base, a supported part supported by the base, a radiation absorbing part receiving radiation and converting the radiation into heat, and a base member corresponding to the heat generated in the radiation absorbing part. A supported portion having a displacement portion that is displaced in a direction opposite to the incident direction of the read light by receiving the read light and changing the received read light into interference light having an interference state corresponding to the displacement of the displacement portion. An interference unit that emits light in a direction, and a majority of the light other than the readout light that is received by the interference unit and converted into the interference light, of the irradiation light, the interference light is emitted from the interference unit. And a deflecting / reflecting means for deflecting and reflecting in a direction inclined with respect to the direction in which the light is read out. 2. The base has a window through which the interference unit receives the readout light and emits the interference light, and the deflection / reflection unit is formed in a predetermined area of the base except the window, and the readout is performed. 2. The device according to claim 1, further comprising a reflecting surface inclined with respect to a light incident direction.
An optical readout radiation-displacement converter according to any of the preceding claims. 3. The method according to claim 1, wherein the reflection surface is formed in a region around the window or on both sides thereof so as to form a trapezoidal space extending from the window as a bottom to the incident side of the readout light. The optical readout radiation-displacement converter according to claim 2. 4. The substrate has a thin-film member having a light-transmitting property with respect to the readout light, and a reinforcing member lining a predetermined region of the thin-film member other than a region corresponding to the window. The optical readout radiation-displacement converter according to claim 2 or 3, wherein a surface is formed on the reinforcing member. 5. An optical read-out radiation-displacement conversion apparatus according to claim 1, wherein said deflecting / reflecting means has a reflection type diffraction grating formed on or provided on said base. 6. An optical read-out radiation-displacement conversion apparatus according to claim 1, wherein said deflecting / reflecting means has a microprism array formed on said substrate or provided on said substrate. 7. A base, a supported part supported by the base, a radiation absorbing part for receiving radiation and converting it to heat, and a base for the base in response to heat generated in the radiation absorbing part. A supported portion having a displacement portion that is displaced by the displacement portion; and an interference unit that receives the readout light, converts the received readout light into interference light having an interference state corresponding to the displacement of the displacement portion, and emits the readout light. The interference unit is a reflector that forms a part of the supported portion and is displaced according to the displacement of the displacement portion, and a half mirror portion fixed to the base so as to face the reflector. A half mirror unit that reflects only a part of the received readout light, and as the heat generated by the radiation absorbing unit increases, the reflection unit and the half unit reduce the intensity of the interference light. Set the distance between the mirror and Light reading type radiation, characterized in that - the displacement converter. 8. The reflectance of said half mirror portion is approximately 1/3.
The optical readout radiation-displacement conversion device according to claim 7, wherein: 9. The light-reading radiation-to-displacement converter according to claim 1, wherein the displacement part has at least two layers of different materials having different coefficients of expansion that are superimposed on each other. apparatus. 10. The device according to claim 1, wherein the supported part and the interference means are one element and a plurality of the elements are provided, and the elements are arranged one-dimensionally or two-dimensionally.
10. An optical readout radiation-displacement converter according to any one of claims 9 to 9. 11. Optical readout radiation according to claim 10.
A displacement converter, irradiating the readout light to the interference means of each element, and responding to the displacement of the displacement part of each element based on the interference light emitted from the interference means of each element. An imaging device, comprising: a readout optical system that forms an optical image. 12. The imaging device according to claim 11, further comprising an imaging unit that captures the optical image.