JP2006113183A - Window structure for observation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide window structure for observation which is used under high-temperature environment and is never broken even though it is thin. <P>SOLUTION: The window structure for observation is provided in which a container whose interior or exterior is under the high-temperature environment is provided with a transparent member (sheet glass) 1 which can transmits light having a prescribed wavelength while maintaining airtightness of the inside and the outside of the container, wherein the transparent member (sheet glass) 1 which constitutes the window is fixed between super-elastic alloys 2a, 2b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is an observation window structure provided for observation and measurement in a container for maintaining a high temperature environment, such as an oven, a high temperature chamber and a high temperature microscope sample installation part, or observation / measurement in a high temperature object or high temperature environment. The present invention relates to an observation window structure of an observation / measurement device for performing the above.

  In high-temperature / heating furnaces such as ovens and high-temperature chambers, flat glass is inserted to observe the inside of the furnace from the outside. Further, when an imaging system consisting of a camera and a lens is arranged in the furnace, a protective housing for protecting the lens itself is used. In this case, a lens or an imaging system itself is contained in a housing provided with an observation window having a transparent member as one component. In a protector for observing a high-temperature object with a microscope, two transparent shielding plates are fixed to the frame at intervals in the thickness direction, as described in JP-A-2001-117016. Yes.

  Since the transparent member constituting such an observation / measurement window is fixed to the furnace, the housing, or the protector, there is a possibility of distortion. When the strain is large, the stress applied to the transparent member is also increased, and in some cases, it is cracked. In order to prevent cracking, it is common practice to increase the thickness of the transparent member to provide strength. However, since the refractive index of a transparent member material such as glass is usually larger than that of air, light passing through the window is refracted. The dotted line in FIG. 8 is a schematic diagram showing the traveling direction of light when the transparent member 20 such as glass is not interposed between the lens 18 and the observation target surface 19, and the solid line is the traveling direction of light when there is interposed. If the transparent member 20 such as glass is not interposed between the lens 18 and the observation target surface 19, the observation light is focused. However, when the transparent member 20 such as glass is interposed, the observation image is blurred without being focused due to refraction of light at the transparent member and the air interface. The degree of blur increases as the glass thickness increases.

Therefore, technology development for thinning the observation window has been made. Japanese Patent Laid-Open No. 2001-214973 has a structure as shown in FIG. A quartz plate glass 1 is fixed with an aluminum sealing 22 interposed therebetween so as to cover the opening of the Kovar metal member 21. The Kovar metal member 18 is fastened by the mounting flange 16 so as to cover the main body flange 4. Since the Kovar metal member has the same thermal expansion coefficient as that of glass, no stress is applied to break the glass even when the furnace reaches a high temperature. In addition, Kovar metal has a folded portion and has an effect of relieving stress applied to quartz glass.
Japanese Patent Laid-Open No. 2001-117016 Japanese Patent Laid-Open No. 2001-214973

  Kovar metal members are very unstable to mechanical deformation and difficult to machine. In the prior art, Kovar processing is performed by a press. However, in order to perform press processing, it is necessary to generate a mold, and when only a small amount is produced, the cost becomes high.

  Therefore, the problem to be solved by the present invention is an observation window structure provided for observation and measurement in a container for maintaining a high-temperature environment, or observation / measurement for observation / measurement in a high-temperature object or high-temperature environment. An observation window structure of a measuring device is to provide a structure that can be thinned and easily manufactured.

  In order to achieve the above object, the observation window structure according to claim 1 of the present application is transparent so that the inside or outside of the container is in a high-temperature environment and light of a predetermined wavelength can be transmitted while keeping the inside and outside of the container airtight. The member is an observation window structure provided in the container, and at least one transparent member is fixed with a superelastic alloy. The observation window structure of claim 2 is characterized in that at least the transparent member closest to the high temperature environment among the transparent members of claim 1 is fixed with a superelastic alloy. The observation window structure of claim 3 is the observation window structure of claims 1 and 2, wherein the superelastic alloy in a state where the transparent member is fixed is in a yielding state. The observation window structure according to claim 4 is characterized in that in the observation window structure according to claims 1 to 3, there is a space on the side surface of the transparent member.

  A superelastic alloy is an alloy that changes from an austenite phase to a martensite phase at room temperature due to an external force and returns to the austenite phase when the external force is unloaded. NiTi alloys, copper-based alloys, and iron-based alloys are known. Superelastic alloys are characterized by a low elastic modulus and a large strain range at yield stress. Therefore, if a transparent member is fixed with a superelastic alloy, even if the transparent member is thermally expanded, the superelastic alloy is deformed without a large increase in stress. Since the stress applied to the transparent member does not become extremely large, it is hard to break. In particular, since the transparent member closest to the high temperature environment has a larger amount of thermal deformation than the other transparent members, fixing the transparent member closest to the high temperature environment with a superelastic alloy is effective as a measure for preventing damage to the optical window.

  Superelastic alloys are almost constant in stress in the yield state. Therefore, if the superelastic alloy fixes the transparent member in a yielded state, the superelastic alloy is deformed with a constant stress even if the transparent member is thermally expanded. Since the stress applied to the transparent member hardly changes, the risk of damage to the transparent member is further reduced.

  Further, if there is a space on the side surface of the transparent member, the transparent member is easily expanded in the horizontal direction as compared with the case where there is no space, so that the amount of deflection of the transparent member due to thermal expansion is reduced.

  Hereinafter, the present invention will be specifically described based on embodiments.

(First Example)
FIG. 1 is a sectional view showing a schematic configuration of an observation window structure according to a first embodiment of the present invention, and FIG. 2 is a plan view. The observation window is provided so as to close the hole 5 formed in the main body flange 4 of the high temperature chamber. It consists of a plate glass 1, superelastic alloys 2a and 2b sandwiching the plate glass, and a vacuum seal 3 that prevents internal air from leaking through the holes 5.

  The plate glass 1 is a synthetic quartz glass disc having a thickness of 2 mm and an outer diameter of 120 mm. The plate glass is fixed by sandwiching the superelastic alloys 2a and 2b with screws. The plate glass 1 may be a heat ray absorption filter, a cold filter, or sapphire glass. The surface of the plate glass 1 is polished and has a surface accuracy of about λ / 10.

  The superelastic alloys 2a and 2b are Ni-Ti alloy disks, and the stress at yield is 420 MPa at room temperature. The centers of the superelastic alloys 2a and 2b are holes having the same outer diameter φ90 mm as the flange holes 5, and are arranged so that the centers of the holes coincide. The superelastic alloys 2a and 2b have eight through holes at equal distances from the center, and bolts 6 are inserted therein. Superelastic alloy 2a is sandwiched between plate glass 1 and superelastic alloy 2b by bolt 6 and fixed to main body flange 4 with screws. The portion where the plate glass 1 of the superelastic alloy 2a is located is dug down over a depth of 2 mm and an inner diameter of 140 mm. The inside diameter of the superelastic alloy 2a is larger than the outside diameter of the plate glass 1. Therefore, in the assembly stage, a space is vacant on the side surface of the glass 1. This space becomes smaller due to the deformation of the superelastic alloys 2a and 2b accompanying the bolt tightening. However, it is not completely buried.

  Similarly to the superelastic alloy 2a, the superelastic alloy 2b has a hole having the same diameter at the center. The superelastic alloy 2b has a through hole at the same position as the superelastic alloy 2a. When the superelastic alloy 2a is fixed with the bolt 6, it is fixed in a state of being sandwiched between the main body flange 4 and the superelastic alloy 2b.

  The main body flange 4 is made of, for example, stainless steel. A hole 5 is formed in the main body flange 4, but the superelastic alloy 2b is installed by screwing so as to surround the hole.

  A circumferential groove for placing the vacuum seal 3 is formed in the main body flange 4 and the superelastic alloy 2b. A vacuum seal composed of an O-ring or gasket made of Viton rubber or the like is placed in each groove.

  Superelastic alloys can be machined without the need to mold like a press. Also, it can be easily assembled only by bolting.

  FIG. 3 shows a schematic configuration diagram of an experimental heating furnace provided with this observation window structure. An electric heater 7 is installed inside the furnace, and the inside of the furnace can be heated by applying a voltage from a power source (not shown). The exhaust port 8 is connected to an exhaust pump (not shown). When installing the sample in the furnace, open and close the observation window.

  In the experiment, the thermocouple 9 was attached to the observation window and the temperature was measured. The thermocouple output signal is sent to a temperature indicator (not shown) to display the furnace window temperature. A vacuum was drawn to 10 torr by an exhaust pump, and the inside of the furnace was heated by an electric heater. Although heating was performed until the window temperature by the thermocouple reached 250 ° C., the observation window was not damaged.

(Second embodiment)
FIG. 4 is an external view of a high-temperature microscope sample installation jig with an observation window according to a second embodiment of the present invention, and FIG. 5 is a cross-sectional view showing a schematic configuration. The observation window in this embodiment includes a plate glass 1, a sheet-like superelastic alloy 10, a vacuum seal 3, a frame 11 made of a superelastic alloy, and a fastener 12 for fastening the sheet-like superelastic alloy.

  The plate glass 1 is a quartz synthetic plate glass having a thickness of 0.8 mm and a length and width of 100 mm. The plate glass 1 is placed on a superelastic alloy frame 11 and pressed and fixed from above by a superelastic alloy sheet 10. The surface of the plate glass 1 is polished and has a surface accuracy of about λ / 10.

  The superelastic alloy sheet 10 is made of a Ni-Ti alloy and has a yield stress of 80 MPa at room temperature. The superelastic alloy sheet 10 is fixed to the frame 11 by two fasteners 12 from above the plate glass 1. The superelastic alloy sheet 10 is sufficiently pulled and fixed in a yielded state. For example, only a spring may be used to determine whether the yield state has been reached. If a sheet-like superelastic alloy with only one spring fixed at one end is pulled and deformed with almost no increase in tensile force, it is considered that a yield state has been reached. Each fastener 12 has two through holes and is fixed to the frame 11 by screwing. In this embodiment, two sheet-like superelastic alloys are used, but two sheets may be stretched in the perpendicular direction, that is, along each side of the plate glass.

  The frame 11 is made of a superelastic alloy. Inside the frame is a circular hole of φ80mm. A groove for fitting the vacuum seal 3 is dug at a position having the same center as the circular hole and a diameter of φ90 mm.

  In addition, when a wall with a distance of 100 mm between walls was provided in the direction along the superelastic alloy sheet, and the frame was such that the plate glass would just fit into the depression, the plate glass was bent when the temperature of the plate glass rose, and the observed image was adversely affected. Therefore, it is better that there is a space on the side surface of the glass, and the structure in which the rectangular parallelepiped has holes as in the present embodiment has the advantage that the manufacturing effort is less.

  In the groove, a vacuum seal 3 made of an O-ring such as Viton rubber or a gasket is fitted and arranged.

  The high temperature microscope sample setting jig includes an observation window having the above-described configuration, a sheet heater 13 with a thermocouple, and a stainless base 14.

  The observation window is installed on the base 14 by welding through the bottom surface of the frame 11. A sheet heater 13 with a thermocouple is installed inside the sample installation jig. The thermocouple seat heater 13 is connected to a stabilized power source (not shown) outside the jig. The base 14 has six through holes and is fixed to a microscope stage (not shown) with screws.

  The observation sample is inserted with the superelastic alloy sheet 10 and the plate glass 1 removed.

  In this example, a roughly polished silicon substrate (not shown) was placed in a high temperature microscope sample setting jig and observed with an objective lens having a magnification of 40 times, a working distance of 6.5 mm, and a numerical aperture of 0.45. A stainless steel plate (not shown) was placed under the thermocouple seat heater 13 to adjust the height so that the distance between the silicon substrate surface and the lower surface of the plate glass 1 was about 2 mm. A voltage was applied to the sheet heater 13 with thermocouple to heat it to 180 degrees. The plate glass 1 was not damaged and the observed image was not deteriorated.

(Third example)
FIG. 6 is a cross-sectional view showing a schematic configuration of a high-temperature microscope sample installation jig with an observation window according to a third embodiment of the present invention. The observation window in the present embodiment uses two plate glasses and can circulate dry air through the gas inlet / outlet 15 therebetween.

  The plate glass 1a inside the jig is pressed by the superelastic alloy sheet 10 as in the second embodiment. A plate glass 1b corresponding to the upper lid of the jig is bonded to a frame 16 made of heat resistant resin. The heat-resistant resin frame 16 is bonded to the superelastic alloy frame 10.

  The superelastic alloy frame 10 has a through hole so that it can be screwed to the base 14. In addition, a groove is dug in the base 14, and the vacuum seal 3 is fitted therein.

  In the configuration of the present embodiment, heat is insulated between the two sheet glasses and the amount of heat passing through the sheet glass 1b is small. Therefore, even if the temperature rising temperature inside the jig is high, the objective lens and the like can be brought closer to the plate glass 1b.

  In the configuration of the present embodiment, only the plate glass 1a having a large thermal strain is fixed with a superelastic alloy. If the glass plate closest to the internal heat source of the container can be fixed with a superelastic alloy and cracking can be prevented, the external glass plate having a smaller heat application often has no problem with the conventional fixing method.

(Fourth embodiment)
FIG. 7 is a sectional view showing a schematic configuration of an observation window structure according to the fourth embodiment of the present invention. In this embodiment, the plate glass 1 is fixed by being pressed onto the main body flange 4 by the mounting flange 17. A superelastic alloy 2c is embedded in the main body flange 4, and the mounting flange 17 is fixed to the superelastic alloy 2c by a bolt 6.

  In the configuration of this example, the plate glass is not directly held by the superelastic alloy. However, since the mounting flange 17 is fixed on the superelastic alloy 2c, it is considered that the plate glass 1 is indirectly fixed to the superelastic alloy 2c. Even if the plate glass 1 is thermally expanded, the superelastic alloy 2c is deformed, so that an effect of preventing cracking can be obtained.

1 is a schematic cross-sectional configuration diagram of an observation window structure according to a first embodiment of the present invention. 1 is a schematic plan configuration diagram of an observation window structure according to a first embodiment of the present invention. 1 is a schematic cross-sectional view of a heating furnace using an observation window structure according to a first embodiment of the present invention. FIG. 6 is an external view of a high-temperature microscope sample installation jig with an observation window according to a second embodiment of the present invention. FIG. 6 is a schematic cross-sectional configuration diagram of a high-temperature microscope sample installation jig with an observation window according to a second embodiment of the present invention. FIG. 6 is a schematic cross-sectional configuration diagram of a high-temperature microscope sample installation jig with an observation window according to a third embodiment of the present invention. FIG. 6 is a schematic cross-sectional configuration diagram of an observation window structure according to a fourth embodiment of the present invention. It is the schematic for showing the advancing direction of the light in the case where the thing with a refractive index different from atmosphere exists between a lens and a measurement object surface for the background art, and when it does not exist. It is a schematic sectional drawing which shows the basic composition of the window part of a high temperature and a vacuum chamber for demonstrating background art.

Explanation of symbols

1,1a, 1b Sheet glass
2a, 2b Superelastic alloy 3 Vacuum seal 4 Body flange 5 Flange hole 6 Bolt 7 Electric heater 8 Exhaust port 9 Thermocouple
10 Superelastic alloy sheet
11 Superelastic alloy frame
12 Fastener
13 Seat heater with thermocouple
14 foundation
15 Gas inlet / outlet
16 Heat-resistant plastic frame
17 Mounting flange
18 lenses
19 Observation surface
20 Transparent materials such as glass
21 Kovar metal parts
22 Sealing

Claims (4)

  An optical window structure provided with a transparent member capable of transmitting light of a predetermined wavelength while keeping the inside and outside of the container hermetic while the inside or outside of the container is in a high temperature environment, and at least one of the transparent members An observation window structure characterized in that is fixed with a superelastic alloy.   2. The observation window structure according to claim 1, wherein at least the transparent member closest to the high-temperature environment is fixed with a superelastic alloy.   3. The observation window structure according to claim 1, wherein the superelastic alloy in a state where the transparent member is fixed is in a yielding state.   The observation window structure according to claim 1, wherein a space is present on a side surface of the transparent member.

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