JP4696250B2 - Infrared imaging video bolometer, metal thin film for infrared imaging video bolometer, and frame member for infrared imaging video bolometer - Google Patents

Description

  The present invention relates to an infrared imaging video bolometer, a metal thin film for an infrared imaging video bolometer, and a frame member for an infrared imaging video bolometer.

  The infrared imaging bolometer is intended for bolometer measurement of incident energy, and its measurement region is assumed to be a wide wavelength region including visible, ultraviolet, extreme ultraviolet, and high energy particle bundles. For example, in a fusion plasma experiment, such a radiant energy flux is a very important measurement object.

  The basic principle of an infrared imaging bolometer (hereinafter referred to as IRIB) is as follows. First, radiation and particle energy are absorbed by a metal thin film, and the temperature rise of the metal thin film is measured in a non-contact manner by an IR detector. And incident power is calculated from the temperature rise of the obtained thin film.

  IRIB was created as a detector that measures the amount of plasma radiation from the temperature change of a metal thin film (Non-patent Document 1, Non-patent Document 2). A method of using an IR camera for measuring the temperature change of a thin film was first proposed in Non-Patent Document 3 describing the relationship between the thin film temperature, wavelength, and S / N ratio during operation. Non-patent document 4 discloses the concept of a two-dimensional IRIB that uses a two-dimensionally divided matrix to project the temperature rise of the absorbent material.

  Further, according to Non-Patent Document 5 and Patent Document 1, this metal thin film has been further developed into a two-dimensional array, designed, assembled, and experimentally tested, and recognized as IRIB (Non-Patent Document 6).

Like many other bolometer detectors, IRIB has the following performance criteria:
(1) Wavelength uniformity, that is, reactivity independent of the type (wavelength) of incident radiation power.

(2) Sensitivity, that is, good sensitivity to the smallest possible incident power.
(3) Have fast time responsiveness.
(4) It has good spatial resolution, that is, the detection area can be minimized.

(5) No crosstalk between detectors.
The multi-channel IRIB 100 realized first is disclosed in Patent Document 1. Here, as shown in FIG. 11A, the frame member 110 sandwiches the thin film 103 between two identically shaped metal masks 102 each having a hole pattern by opening a plurality of holes 101 in a two-dimensional array. The both surfaces of the thin film 103 are exposed from the holes 101 of the metal masks 102, respectively. And as shown in FIG.11 (b), the single side | surface of the frame member 110 faces the plasma through the pinhole 112 or the slit. On the other hand, the IR camera 120 observes the back surface of the frame member 110 whose surface is blackened, and observes the temperature rise of each pixel caused by radiation incident from the surface of the thin film 103. The metal mask 102 serves as a heat sink for each pixel, and the coefficient (that is, sensitivity) K and the thermal diffusion time τ of each pixel are determined by the size, thickness, and heat conduction characteristics. The thickness tf of the thin film 103 is determined so as to be able to absorb the assumed maximum energy photons. The diameter of the thin film 103 is determined so that the thermal diffusion time τ of each pixel matches the frame interval Δt of the camera.

  The relationship between the pixel diameter dpix and its thermal diffusion time τ is given by equation (1).

（１）式中、κは薄膜の金属特性による熱拡散係数である。

In the formula (1), κ is a thermal diffusion coefficient due to the metal characteristics of the thin film.

  If the value of the thermal diffusion time τ is too large, the measurement time interval is not sufficient, and there is a problem that the amount of heat absorbed last time before the next measurement does not decrease to the reference value. If the value of time τ is too small, thermal diffusion will occur too quickly.

The spatial resolution of IRIB is determined by the pinhole and camera geometry.
Each pixel has a known output power, and a He-Ne laser beam choppered at a certain frequency is incident on the blackened thin film surface, and the signal calibration is performed by obtaining the values of the thermal diffusion time τ and the thermal diffusion coefficient κ. it can. The power of the emitted light to each pixel is given by equation (2).

（２）式中、Ｔは、抵抗型金属フイルムボロメーターの場合と同じように、マスクの温度を考慮した金属薄膜の温度である。Ｋは、Ｋ＝τ／Ｃであり、Ｃは金属薄膜の熱容量である。

In the formula (2), T is the temperature of the metal thin film in consideration of the temperature of the mask, as in the case of the resistance type metal film bolometer. K is K = τ / C, and C is the heat capacity of the metal thin film.

  In the conventional bolometer as described above, various problems arise from a matrix-like mask separated into segments. The first problem is that if there is a dent in the metal mask, there is not enough contact between the metal mask and the metal thin film at the edge of the pixel, and the mask does not act as a heat sink, and the heat is like crosstalk between adjacent pixels. Leaking beyond the mask to pixels that originally have no signal. The second problem is that part of the pixel edge becomes a shadow of the edge of the mask because the mask has a thickness. The third problem arises from the above shadow, but when spraying the carbon spray used for blackening on the metal thin film, the surface of the metal thin film and the copper mask on it is not flush. The carbon film is not uniform.

  In addition, a large number of pixels are fixed by a mask separated into segments, and a part of the metal thin film covering the mask becomes a structure that cannot be used as a shadow of the mask, so that the spatial resolution is lowered.

  Next, infrared imaging video bolometers (hereinafter referred to as IRVB) disclosed in Non-Patent Document 7 and Non-Patent Document 8 have been proposed. This content is already patented in Patent Document 2. The IRVB has been modified to remove the mask separating the pixels from the IRIB and to use a copper frame 200 to hold the large metal film 202 as shown in FIG. In the IRVB of Patent Document 2, the detectable area is increased by about 60% and the spatial resolution can be increased by about 25% compared to the conventional IRIB. The above-described problem of the concave portion on the mask is solved by firmly fixing the copper frame 200 and the edge of the frame 200 with screws (not shown) and bringing the copper frame into close contact with the metal thin film, Further improvements are possible through the use of indium gaskets.

Moreover, the shadow on the metal thin film by the copper mask in IRIB can also be prevented. Furthermore, IRVB has the experimental flexibility that the size and number of bolometer pixels can be varied depending on the experimental situation in order to adapt the sensitivity to the signal intensity. In addition, while IRIB images are divided, IRVB is characterized in that a full video image of plasma radiation can be obtained.
TFR Group (presented by AL Pecquet), Journal of Nuclear Materials, 93-94, 377 (1980) JC Ingraham and G. Miller, Rev. Sci. Instrum. 54, 673 (1983) G. Apruzzese and G. Tonini, Rev. Sci. Instrum. 61, 2976 (1990) GA Wurden, in Diagnostics for Experimental Thermonuclear Fusion Reactors, edited by PE Stott et al, (Plenum, New York, 1996), pp, 603-606. GA Wurden, BJPeterson and Sudo, Rev. Sci. Instrum. 68,766 (1997). GA Wurden, and BJPeterson, Rev. Sci. Instrum. 70, 255 (1999). BJPeterson, Rev. Sci. Instrum. 71, 3696 (2000). BJPeterson, Rev. Sci. Instrum. 74, 2040 (2003). US5861625 specification Japanese Patent No. 3390913

  However, it has been found that the conventional IRVB has the following problems. First, the incident power is not a simple function of local bolometer pixel temperature alone, and temperature diffusion needs to be considered. This temperature diffusion is calculated from the temperature difference between adjacent pixels. However, the temperature difference between adjacent pixels is smaller than the temperature rise due to incident power. For this reason, subtraction between values close to the calculation of the incident power is included, which causes an error. As a result, there is a problem that sensitivity is lowered.

  Second, since the metal thin film is fixed to the copper frame, much of the incident power is lost through the frame. For this reason, the part which is not spent for the temperature rise of a thin film among incident power increases. In addition, the metal thin film needs to have a sufficient thickness (about 10 microns) in order to absorb high energy photons. However, if the thin film is made thicker, loss due to heat conduction increases. This also reduces the sensitivity of IRVB.

  It is a first object of the present invention to provide an infrared imaging video bolometer that can improve sensitivity. The second object of the present invention is to provide a metal thin film used for an infrared imaging video bolometer capable of improving sensitivity. It is a third object of the present invention to provide a frame member used in an infrared imaging video bolometer that can improve sensitivity.

In order to achieve the above object, the invention of claim 1 is attached to a vacuum vessel in which plasma is confined, and is blackened to avoid light reflection from the plasma;
An infrared vacuum window provided on the end face of the light shield tube and attached to the vacuum vessel;
A plate having a pinhole or slit for taking in light from plasma, provided on the end face of the light shield tube opposite to the infrared vacuum window;
A metal thin film body mounted in the light shield tube so as to be parallel to the plate;
Infrared imaging bolometer having an infrared video camera for viewing the thin film through the infrared vacuum window,
The metal thin film body includes a first metal thin film that forms a heat insulating layer, and a second metal thin film that is stacked on the heat insulating layer and forms a plurality of radiation absorbing layers arranged with gaps therebetween. An infrared imaging video bolometer including the second metal thin film supported only by the first metal thin film is included.

  The invention of claim 2 is characterized in that, in the thermal insulation layer, the region where the radiation absorbing layer is laminated is made thinner than the region of the thermal insulation layer provided with the gap. To do.

A third aspect of the present invention is characterized in that, in the first aspect, in the thermal insulating layer, a region where the radiation absorbing layer is laminated is removed, and a part of the radiation absorbing layer is exposed.
According to a fourth aspect of the present invention, in any one of the first to third aspects, the metal thin film body is attached to the light shield tube while being sandwiched between two frames made of a heat conductive material. Each frame is provided with one window slightly smaller than the size of the metal thin film body, and the metal thin film body is held so as to be exposed to the plasma side and the infrared camera side so as to cover the window. The metal thin film body and the two frames constitute a frame member.

According to a fifth aspect of the present invention, there is provided a first metal thin film that forms a heat insulating layer, and a second metal thin film that is stacked on the heat insulating layer and forms a plurality of radiation absorbing layers disposed with a gap therebetween. And a metal thin film body for an infrared imaging video bolometer, characterized in that the second metal thin film is supported only by the first metal thin film .

According to a sixth aspect of the invention, according to claim 5, in the heat insulating layer, a region where the radiation absorbing layer are stacked, and characterized in that it is thinner than the area of the heat insulating layer in which the gap is provided To do.

A seventh aspect of the invention is characterized in that, in the fifth aspect, in the thermal insulating layer, a region where the radiation absorbing layer is laminated is removed, and a part of the radiation absorbing layer is exposed.
The invention according to claim 8 is the metal thin film body according to any one of claims 5 to 7 and two frames made of a heat conductive material, each frame having a size of the metal thin film body. A slightly smaller window, a frame held between the metal thin film body so as to cover the window and exposed to the plasma side and the infrared camera side, and The gist of the frame member for an infrared imaging video bolometer is provided.

  According to the first to fourth aspects of the present invention, the heat transfer in the radiation absorbing layer caused by absorbing the photons is suppressed by the heat insulating layer, so that the sensitivity of IRVB can be improved.

The inventions according to claims 5 to 7 can provide a metal thin film body used in an infrared imaging video bolometer capable of improving the sensitivity of IRVB.
The invention according to claim 8 can provide a frame member used for an infrared imaging video bolometer capable of improving sensitivity.

Hereinafter, an infrared imaging video bolometer embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, an infrared imaging video bolometer (IRVB) 10 is provided in a vacuum vessel 1 for confining plasma. An end of the light shield tube 3 of the infrared imaging video bolometer 10 is attached to the vacuum container 1. The inner surface of the light shield tube 3 is blackened by carbon spray in order to avoid light reflection from the plasma. In the light shield tube 3, an infrared vacuum window 5 is provided on the end face of the end. A plate 7 is provided on the end face of the light shield tube 3 opposite to the infrared vacuum window 5. A pinhole or slit 9 is formed in the plate 7, and light from the plasma is taken into the light shield tube 3 through the pinhole or slit 9.

  Further, a frame member (mask) 11 is provided in the light shield tube 3 so as to be parallel to the plate 7, and is spaced apart from the plate 7. The frame member 11 is provided with a metal thin film body 40 as shown in FIG. Further, an infrared video camera 13 is provided outside the vacuum vessel 1 in the vicinity of the infrared vacuum window 5 so that the thin film of the frame member 11 can be viewed through the infrared vacuum window 5 by the infrared video camera 13. It has become.

Next, the structure of the frame member 11 including the IRVB metal thin film body 40 will be described with reference to FIGS.
As shown in FIG. 3, the frame 21 includes two circular frames, a front frame 21a and a back frame 21b, and is made of non-oxidized copper as a heat conductive material having the following holes. The material of the frame 21 is not limited to non-oxidized copper, and is not limited as long as the material is excellent in thermal conductivity. In addition, a square window 29 having a size slightly smaller than that of the metal thin film body 40 is provided in the central portion of the frame 21. The shape of the window 29 is not limited to a square, and may be a shape corresponding to the outer shape of the metal thin film body 40. If the metal thin film body 40 is, for example, a circular shape, the window 29 is slightly smaller in size. Other shapes such as a circle may be used.

  The front frame 21a and the back frame 21b have four holes, that is, assembly bolt holes 23, arranged at equal intervals along the edge in order to attach the light shield frame 21.

  Further, four fixing bolt holes 25 are formed in the upper, lower, left and right sides of the front frame 21a and the back frame 21b in order to tighten the bolts. As a result, the metal thin film body 40 described later is fixed, and sufficient thermal contact is provided between the metal thin film body 40 and the frame 21.

  Further, a vent hole 31 as shown in FIGS. 3 and 4 is formed in the front frame 21a and the back frame 21b so that air can pass therethrough, and the air pressure does not differ on both sides of the metal thin film body 40 by the vent hole 31. Has been.

  The vent hole 31 does not allow light to pass directly from the vent hole (hole) 31, and the structure is shown in FIG. 4 when viewed from the cross section so that the other cannot be seen through the vent hole 31 when viewed from either side. It is a crank type as shown.

  A bolt (not shown) made of stainless steel is attached to the assembly bolt hole 23 and fixing bolt hole 25 through a washer made of stainless steel and cooperates with a nut (not shown). The metal thin film body 40 is sandwiched and fixed between the frame 21a and the back frame 21b.

  As shown in FIGS. 5A and 5B, the metal thin film body 40 includes a first metal thin film 41 constituting a heat insulating layer and a plurality of first metal thin film bodies constituting a radiation absorbing layer laminated on the first metal thin film 41. 2 metal thin film 42. The first metal thin film 41 is preferably of a high tensile strength because it is stretched on the window 29, and the second metal thin film 42 is used to suppress heat transfer between the adjacent second metal thin films 42 via the gap G. A material having a low thermal conductivity is preferable. For this reason, the first metal thin film 41 is selected from those having high tensile strength and low thermal conductivity, such as stainless steel or titanium.

Moreover, although the film thickness of the 1st metal thin film 41 has preferable 1-10 micrometers, it is not limited to this range.
The plurality of second metal thin films 42 are arranged in a matrix as shown in FIGS. 2 and 5A and are separated from each other via a gap. The second metal thin film 42 may be a metal that generates infrared rays by absorbing photons from plasma, and this material has a high photon attenuation coefficient, such as Au (gold), Pt. (Platinum), W (tungsten), Ta (tantalum), Hf (hafnium), and Pb (lead).

  Moreover, since the energy region of the photon that can be absorbed is different when the film thickness is different, the second metal thin film 42 is incident by preparing a film thickness corresponding to the measurement target (photon) having the energy region to be measured. Separation of radiation and particle energy is possible.

  Further, the shape of the block of the second metal thin film 42 may be square or rectangular when viewed in plan, and may be other shapes, and the shape is not limited. The second metal thin films 42 are spaced apart from each other with a gap G as shown in FIGS. The gap G of the second metal thin film 42 can be formed by removing the unmasked region by dry etching while masking the region that will later become the second metal thin film 42 with a photoresist.

  In addition, in the 1st metal thin film 41 which laminates | stacks the 2nd metal thin film 42 shown to Fig.5 (a), (b), although the 1st metal thin film 41 whole is formed with the same film thickness, it is limited to this structure. It is not something. As shown in FIG. 6, you may remove the one part area | region of the 1st metal thin film 41 which laminates | stacks the 2nd metal thin film 42. As shown in FIG. For example, in the example shown in FIG. 6, an exposed window 41 a having a size smaller than that of the second metal thin film 42 is formed, leaving the overlapping region OV between the first metal thin film 41 and the second metal thin film 42. The plasma side surface of the thin film 42 is exposed.

In the case where the plasma side surface of the second metal thin film 42 is exposed, the exposed window 41a is formed by scraping the first metal thin film 41 by ion beam etching, for example.
The metal thin film body 40 and the frame 21 on the infrared video camera 13 side are painted black with carbon spray in order to increase the emissivity of the metal thin film body 40, and the sensitivity is improved. An indium gasket (not shown) is interposed between the metal thin film body 40 and the frame 21 and is used to improve the thermal contact between the metal thin film body 40 and the frame 21.

(Function)
Next, the temperature distribution in the second metal thin film 42 configured as described above will be described.
The temperature distribution of the second metal thin film 42 (hereinafter also referred to as an absorption block) can be calculated as a function of incident power by the finite element method.

  In this case, the element size L of the thin film element is selected to be sufficiently small with respect to the size of the absorption block itself, and the time step Δt is made sufficiently smaller than the response time of the absorption block. By setting in this way, the temperature rise of each thin film element is given by the following equation (3) by the finite element method.

上記のようにして個々の薄膜要素の温度上昇について得られることから、ここで、放射フラックスが入射し始める時刻（ｔ＝０）での温度を３００Ｋ（すなわち、Ｔx,y＝３００Ｋ）と仮定し、ｔ＝1000ms後における吸収ブロックの温度分布の計算結果を図７に示す。

Since the temperature rise of each thin film element is obtained as described above, it is assumed here that the temperature at the time (t = 0) at which the radiation flux begins to enter is 300 K (ie, Tx, y = 300 K). FIG. 7 shows the calculation result of the temperature distribution of the absorption block after t = 1000 ms.

In FIG. 7, the z axis is temperature (unit K), the x and y axes are element numbers, and the size of each thin film element is 0.525 mm. In this case, the structure of the metal thin film body 40 is such that the first metal thin film 41 is made of stainless steel having a film thickness of 1 μm, the size of the exposed window 41a is 4.2 mm × 4.2 mm, and The size was 2.5 μm × 6.3 mm × 6.3 mm, and the gap G was 1.05 mm. Further, P _rad (incident radiation power) was set to 3 mW / cm ² .

  As shown in FIG. 7, it can be seen that the temperature change in the region in the absorption block is smaller than the temperature increase in the absorption block. Therefore, it can be considered that the absorption block is thermally insulated and has a uniform temperature distribution.

In order to perform calibration with a bolometer, the time response of the temperature of the absorption block may be measured under radiation having a known incident power and an arbitrary spread, similarly to IRIB.
In addition, incident power can be approximated using Formula (2). The coefficient K and the thermal diffusion time τ can be obtained from fitting by a mathematical method. This fitting will be described.

As shown in FIG. 10, the metal thin film is irradiated with a _laser with a known power P _laser with a chopper, and the temperature change of the metal thin film is measured by the laser irradiation. By laser irradiation, the temperature of the metal thin film rises and the temperature at saturation becomes the maximum temperature Tmax. On the other hand, when the temperature of the metal thin film decreases with the laser irradiation stopped, the temperature at saturation becomes the minimum temperature Tref. . Tref is the ambient temperature around the metal thin film.

At this time,
K = Tmax / P _laser
And also
T−Tref = Tmax (1−e ^{−t / τ} )
Therefore, the coefficient K and the thermal diffusion time τ can be obtained by the above two equations.

Next, the conversion efficiency of this embodiment will be described with reference to FIG.
FIG. 8 shows the distribution of incident radiation energy, where the solid line indicates incident energy, the dotted line indicates infrared radiation, and the alternate long and short dash line indicates heat conduction loss. In FIG. 8, the y-axis indicates the energy ratio (%), and the x-axis indicates the element number. The size of the thin film element in the embodiment is 0.525 mm.

The configuration of the metal thin film body 40 is the configuration shown in FIG. Specifically, the first metal thin film 41 is made of stainless steel having a thickness of 1 μm, the size of the exposed window 41a is 4.2 mm × 4.2 mm, and the size of the absorption block (second metal thin film 42) is 2.5 μm × 6.3 mm × 6.3. mm, and the gap G was 1.05 mm. Also, Prad (incident radiation power) was 3 mW / cm ² .

  FIG. 9 shows the distribution of incident radiant energy in the comparative example, where the solid line indicates incident energy, the dotted line indicates infrared radiation, and the alternate long and short dash line indicates heat conduction loss. In FIG. 9, the y-axis indicates the energy ratio (%), and the x-axis indicates the element number. The size of the thin film element in the comparative example is 0.525 mm.

Further, the metal thin film body in FIG. 9 is constituted by a single metal thin film of the prior art (that is, Patent Document 2). Specifically, the metal thin film is made of Au (gold) with a film thickness of 2.5 μm. Further, P _rad (incident radiation power) was set to 3 mW / cm ² .

In the case of the present embodiment, as shown in FIG. 8, 35% to 45% of the incident power is converted into infrared radiation, and 65% to 55% is lost due to heat conduction.
On the other hand, in IRVB so far, as shown in FIG. 9, only 1% to 1.5% is converted into infrared radiation, and 98.5% to 99% is lost due to heat conduction.

The effects exhibited by this embodiment will be described below.
(1) In the infrared imaging video bolometer 10 of the present embodiment, the metal thin film body 40 is laminated on the first metal thin film 41 (thermal insulating layer) and the first metal thin film 41 and through the gap G. It is comprised so that the some 2nd metal thin film 42 (radiation absorption layer) arrange | positioned may be included.

  As described above, since the plurality of second metal thin films 42 are arranged apart from each other and the first metal thin film 41 has a smaller heat conduction than the second metal thin film 42, the heat conduction between the blocks is disclosed in the technique of Patent Document 2. It is possible to reduce to 1/20 to 1/100.

According to this embodiment, the loss due to heat conduction can be made very small with respect to the energy radiated as infrared rays, and as a result, the sensitivity of IRVB can be improved.
(2) In the configuration shown in FIG. 6 of the present embodiment, a part of the region where the second metal thin film 42 (radiation absorption layer) is laminated is removed from the first metal thin film 41 (thermal insulating layer). A part of the two-metal thin film 42 (radiation absorption layer) is exposed.

  As a result, the time scale of the temperature rise due to the incident radiation power of the second metal thin film 42 (radiation absorption layer) is less affected by the heat capacity of the first metal thin film 41 (thermal insulating layer), and the second metal thin film 42 ( It depends on the heat capacity of the radiation absorbing layer.

  On the other hand, in the configuration shown in FIG. 5B, the incident radiation power is affected by the heat capacity of the first metal thin film 41 (thermal insulating layer) on which the second metal thin film 42 (radiation absorption layer) is laminated. The time scale of the temperature rise due to depends on the total heat capacity of the first metal thin film 41 and the second metal thin film 42.

Therefore, in the configuration shown in FIG. 6, when the incident radiation power is the same, the temperature rise due to the radiation power can be accelerated, and quick time response can be achieved.
(3) In the frame member 11 of the present embodiment, the metal thin film body 40 is attached to the light shield tube 3 while being sandwiched between the front frame 21a and the back frame 21b made of a heat conductive material, and is attached to each frame. One window 29 slightly smaller than the size of the metal thin film body 40 is provided. The metal thin film body 40 is held so as to be exposed to the plasma side and the infrared camera side so as to cover the window 29, and the frame member 11 is constituted by the metal thin film body 40 and the two frames. By being comprised in this way, IRVB which has the effect of said (1) or (2) can be provided.

  (4) In the metal thin film body 40 for the infrared imaging video bolometer of the present embodiment, the first metal thin film 41 (thermal insulating layer) and the first metal thin film 41 are stacked and disposed with a gap G therebetween. The plurality of second metal thin films 42 (radiation absorption layers) formed are included.

As a result, a metal thin film used for an infrared imaging video bolometer that can improve the sensitivity of IRVB can be provided.
(5) In the metal thin film body 40 for the infrared imaging video bolometer of the present embodiment, the region where the second metal thin film 42 (radiation absorption layer) is laminated is removed from the first metal thin film 41 (thermal insulating layer). Thus, a part of the second metal thin film 42 is exposed.

As a result, the temperature rise due to radiation power can be accelerated, and a metal thin film body used for an infrared imaging video bolometer having a quick time response can be provided.
(6) The frame member 11 of the present embodiment includes the metal thin film body 40, and a front frame 21a and a back frame 21b made of a heat conductive material. Each frame is provided with one window 29 slightly smaller than the size of the metal thin film body 40, and the metal thin film body 40 is sandwiched between the frames so as to cover the window 29, so that the plasma side And it was held to be exposed to the infrared camera side.

As a result, it is possible to provide a frame member used in an infrared imaging video bolometer that can improve sensitivity.
(7) When compared with the conventional IRIB, the metal thin film body having two layers according to the present embodiment has the following advantages 1) to 3).

1) Sensitivity is increased 5 to 20 times.
2) Problems due to the use of the mask, such as a part of the vixel being shaded or the mask not functioning as a heat sink due to insufficient contact, are eliminated.

3) The spatial resolution is increased by up to 25%.
(8) Further, when compared with conventional IRIB and IRVB, the metal thin film body having two layers according to the present embodiment has the following advantages 1) and 2).

1) Sensitivity increases 3 to 10 times on a time scale of 50 to 1000 ms.
2) The calibration procedure can be simplified.
In addition, the said embodiment can also be changed and comprised as follows.

  In the configuration of the embodiment, in the first metal thin film 41 (thermal insulating layer), the thickness of the region where the second metal thin film 42 is stacked is the thickness of the region where the gap G is provided between the first metal thin films 41. It may be formed thinner. Even if comprised in this way, with respect to the energy radiated | emitted as infrared rays, the loss by heat conduction can be made very small, As a result, the sensitivity of IRVB can be improved.

The figure which shows the whole structure of IRVB of one Embodiment which actualized this invention. The perspective view of the frame member of the infrared imaging bolometer of one Embodiment of this invention. The figure which decomposed | disassembled the flame | frame of the infrared imaging bolometer of one Embodiment similarly. FIG. 3 is a cutaway sectional view of a vent hole in the frame of the infrared imaging bolometer of the same embodiment. (A) is a perspective view of a metal thin film body similarly, (b) is sectional drawing. Sectional drawing of the metal thin film body of other embodiment. The figure which shows the temperature distribution of an absorption block. The figure which shows distribution of the incident radiation energy in this embodiment. The figure which shows distribution of the incident radiation energy in a comparative example. The graph which shows laser irradiation and the temperature change of a metal thin film. (A) is a disassembled perspective view of the conventional frame member, (b) is a schematic perspective view of conventional IRIB100. The front view of another conventional frame member.

Explanation of symbols

1 ... Vacuum container, 3 ... Light shield tube, 5 ... Infrared vacuum window,
7 ... plate, 9 ... pinhole or slit,
10 ... Infrared imaging video bolometer, 11 ... Frame member,
13 ... Infrared video camera, 21 ... Frame, 21a ... Front frame,
21b ... Back frame 21b, 29 ... Window, 40 ... Metal thin film body,
41 ... 1st metal thin film (thermal insulation layer), 42 ... 2nd metal thin film (radiation absorption layer),
G ... Gap.

Claims (8)

A light shield tube attached to a vacuum vessel in which the plasma is confined, and blackened to avoid light reflection from the plasma;
An infrared vacuum window provided on the end face of the light shield tube and attached to the vacuum vessel;
A plate having a pinhole or slit for taking in light from plasma, provided on the end face of the light shield tube opposite to the infrared vacuum window;
A metal thin film body mounted in the light shield tube so as to be parallel to the plate;
Infrared imaging bolometer having an infrared video camera for viewing the thin film through the infrared vacuum window,
The metal thin film body includes a first metal thin film that forms a heat insulating layer, and a second metal thin film that is stacked on the heat insulating layer and forms a plurality of radiation absorbing layers arranged with gaps therebetween. An infrared imaging video bolometer including a second metal thin film supported only by the first metal thin film .   2. The infrared imaging video bolometer according to claim 1, wherein a region where the radiation absorbing layer is laminated in the thermal insulating layer is thinner than a region of the thermal insulating layer provided with the gap. 3. .   2. The infrared imaging video bolometer according to claim 1, wherein a region where the radiation absorbing layer is laminated is removed from the thermal insulating layer, and a part of the radiation absorbing layer is exposed. 3. The metal thin film body is attached to the light shield tube in a state sandwiched between two frames made of a heat conductive material,
Each frame is provided with one window slightly smaller than the size of the metal thin film body, and the metal thin film body is held so as to be exposed to the plasma side and the infrared camera side so as to cover the window. The infrared imaging video bolometer according to any one of claims 1 to 3, wherein a frame member is constituted by the metal thin film body and the two frames. A first metal thin film that forms a heat insulating layer ; and a second metal thin film that is stacked on the heat insulating layer and forms a plurality of radiation absorbing layers disposed with a gap therebetween. A metal thin film body for an infrared imaging video bolometer, characterized in that the second metal thin film is supported only by the above . 6. The infrared imaging video bolometer according to claim 5 , wherein a region where the radiation absorbing layer is laminated in the thermal insulating layer is made thinner than a region of the thermal insulating layer provided with the gap. Metal thin film body.   6. The metal for infrared imaging video bolometer according to claim 5, wherein a region where the radiation absorbing layer is laminated is removed from the heat insulating layer, and a part of the radiation absorbing layer is exposed. Thin film body. The metal thin film body according to any one of claims 5 to 7,
Two frames made of heat-conducting material,
Each frame is provided with one window slightly smaller than the size of the metal thin film body, and the metal thin film body is sandwiched between the frames so as to cover the window and exposed to the plasma side and the infrared camera side. A frame that is held to
A frame member for an infrared imaging video bolometer, comprising:

Images