JPH0571923B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cryogenic fiberscope used for observation in a cryogenic medium such as liquefied gas, and in particular to a cryogenic fiberscope used for observation in a cryogenic medium such as liquefied gas. This improves handling operability and reliability.

[Prior Art] Since the behavior of materials in cryogenic media such as liquefied natural gas and liquid nitrogen cannot be directly observed, observation using a fiberscope has conventionally been performed.

Figure 2 shows a conventional cryogenic fiberscope used in a cryogenic medium L, and the reference numeral 1 in the figure is an image transmitter that transmits an image of a sample S immersed in a cryogenic medium L. It is. This image transmission body 1
consists of an image fiber, etc., which is a condensed optical fiber, and there are two eyepiece tubes at each end of the image transmitting body.
and a sensor probe 3 are attached, so that the sample S can be observed by immersing the sensor probe 3 into a cryogenic medium L such as liquid nitrogen.
An eyepiece lens 4 made of a convex lens or the like is provided within the eyepiece tube 2, so that the image of the sample S transmitted by the image transmitter 1 can be viewed. The sensor probe 3 is a generally cylindrical body made of stainless steel or the like so as to protect the image transmitting body 1 and the like housed therein from extremely low temperatures and external stress. A suction pipe 5 is attached to create a reduced pressure state. One end of the sensor probe 3 connected to the image transmitting body 1 is sealed by a flange 6, and the other end has objective lenses 7, 7 inside.
An objective lens barrel 9 is attached which houses the sensor probe 3 and is sealed by a transparent window 8, so that the inside of the sensor probe 3 is kept airtight. Furthermore, a suction device 10 such as a suction pump is connected to a suction pipe 5 branched from the side of the sensor probe 3.
The interior of the sensor probe 3 can be brought into a reduced pressure state of 10 ^-1 to ^{10 -4} torr. Thereby, even when the sensor probe 3 is immersed in the cryogenic medium L, it is possible to prevent dew condensation on the image transmitting body 1, objective lenses 7, 7, etc. housed therein.

[Problems to be Solved by the Invention] However, in the case of a cryogenic fiberscope as shown in FIG. Since it is necessary to maintain the inside of the apparatus 3 in a reduced pressure state, the suction device 10 is indispensable, which poses a problem of low operability during observation. Furthermore, when observation is carried out over a long period of time, outside air may flow back from the suction device 10 into the sensor probe 3, which is in a reduced pressure state at an extremely low temperature, resulting in condensation on the objective lenses 7, 7, etc. The reliability of the images obtained decreased, and in some cases, the images became unobservable.

This invention has been made to solve the above problems, and an object of the invention is to provide a fiberscope for cryogenic use that has good operability and reliability.

[Means for Solving the Problems] The cryogenic fiberscope of the present invention comprises an eyepiece tube provided with an eyepiece, an objective tube provided with an objective lens, and an image obtained with the objective tube. The fiberscope for cryogenic use is composed of an image transmitting body that transmits the image to the eyepiece tube, the inside of the objective tube is in a reduced pressure state, both ends of which are sealed with transparent windows, and one of the windows has the image transmitter that transmits the image to the eyepiece tube. The image transmitting bodies are connected in a butt state, or the inside of the objective lens barrel is filled with a gas having a boiling point lower than that of the cryogenic medium in which the objective lens barrel is immersed, and both ends thereof are sealed with transparent windows, The solution was to connect the image transmitting body to one side of the window in an abutted state.

[Function] In the cryogenic fiberscope according to claim 1, since the inside of the objective lens barrel is in a reduced pressure state, dew condensation does not occur on the objective lens even if the objective lens barrel is immersed in a cryogenic medium such as liquid helium. do not have.

In the cryogenic fiberscope according to the second aspect, since the objective lens barrel is filled with a gas having a lower boiling point than the cryogenic medium in which the cryogenic fiberscope is immersed, dew condensation does not occur on the objective lens.

Furthermore, in either of the fiberscopes for cryogenic temperatures according to claims 1 and 2, since the objective lens barrel and the image transmitter are connected in a butt state, dew condensation occurs between the objective lens barrel and the image transmitter. In addition, even if a cryogenic medium intervenes between the objective lens barrel and the image transmitting body, a uniform thin film layer is formed, so that measurement is not adversely affected.

[Example] This invention will be explained in detail below.

FIG. 1 shows an embodiment of the cryogenic fiberscope according to claim 1 of the present invention, and FIG.
The difference from the conventional one shown in the figure is that the sensor probe 3 and the suction device 10 are not necessary, and the image transmitting body 1 is directly connected to the objective lens barrel 9 in abutted state.

The objective lens barrel 9 is a cylindrical body made of stainless steel, quartz glass, sapphire, etc., which has good durability against extremely low temperatures and external stress, and has a sample S immersed in a cryogenic medium L inside. Objective lenses 7, 7 made of convex lenses etc. that enable observation of
is provided. The objective lens barrel 9 has a window made of quartz glass, sapphire, or the like, which is durable against extremely low temperatures and external stress, and is transparent to the measurement light transmitted within the image transmitter 1. 8 and 8, both ends of which are vacuum sealed.
The internal pressure of the objective lens barrel 9 may be in a reduced pressure state such that the objective lenses 7, 7 do not condense when the objective lens barrel 9 is immersed in the cryogenic medium L, and may vary depending on the type of the cryogenic medium L. You can choose as appropriate, but 10 ^-1
A reduced pressure of ~10 ^-4 torr is preferred. Also, outside one window 8 of the objective barrel 9, the other end is provided with an eyepiece barrel 2.
One end of the image transmitting body 1 connected to the eyepiece tube 2 is directly connected to the eyepiece tube 2 so that the image of the sample S obtained by the objective lens barrel 9 can be transmitted to the eyepiece tube 2.

In this way, even when the objective lens barrel 9 and the image transmitter 1 are immersed in the cryogenic medium L when observing the sample S, the inside of the objective lens barrel 9 is maintained in a reduced pressure state.
In addition, since the objective lens barrel 9 and the image transmitting body 1 are connected in abutting state, there is no possibility of dew condensation on the objective lenses 7, 7 or the end faces of the image transmitting body 1. Furthermore, a cryogenic medium L is provided between the image transmitting body 1 and the objective lens barrel 9.
Even if it enters, the cryogenic medium L forms a uniform thin film layer, so that it will not adversely affect the images obtained with the cryogenic fiberscope of the present invention. Furthermore, since both ends of the objective lens barrel 9 are vacuum-sealed by the windows 8, 8, there is no need for a suction device like in conventional cryogenic fiberscopes.
This not only improves the operability when observing the sample S, but also facilitates observation over a long period of time. Furthermore, cryogenic fiberscopes can be made smaller, enabling a wide range of applications. Furthermore, in the cryogenic fiberscope of the present invention, only the objective lens barrel 9 can be easily replaced, so maintainability is improved. Furthermore, since the end of the image transmitter 1 does not pass through the window 8 of the objective lens barrel 9, the structure of the joint between the objective lens barrel 9 and the image transmitter 1 is simple, and it is liquid-tight. will be maintained at a high level.

The cryogenic fiberscope according to claim 2 of the present invention has a cryogenic medium L in the objective mirror 9 of the cryogenic fiberscope according to claim 1 shown in FIG.
For example, when observing in liquid nitrogen, helium, which has a boiling point of 4K, which is lower than the liquid temperature of liquid nitrogen of 90K, is sealed in the objective lens barrel 9. It is sealed in. In this way, even if the objective lens barrel 9 is immersed in liquid nitrogen, there will be no condensation on the lenses 7, 7 or the end face of the optical path 1 since the temperature is above the boiling point of helium. Furthermore, when the objective barrel 9 is filled with gas, the pressure inside the objective barrel 9 and the pressure of the cryogenic medium L can be equalized, unlike the cryogenic fiberscope according to claim 1. This is preferable because the windows 8, 8 attached to both ends of the tube 9 can be prevented from being damaged, and the strength can be improved.

In addition to using an image fiber as the image transmitting member 1, the cryogenic fiberscope according to any of claims 1 and 2 can also use a fiber, a rod, etc. for image transmission, and in particular, a fiber scope with a refractive index can be used. By using a self-occurring lens, which is an image transmitting body distributed parabolically from the central axis toward the outer circumferential surface, with cover glasses bonded to both ends, a deep depth of focus and clear images can be obtained. suitable.

In addition, in the cryogenic fiberscope shown in Fig. 1, two optical systems are used to observe the sample S.
Although two objective lenses 7, 7 and one eyepiece lens 4 are used, these optical systems are not limited to this example, and a plurality of eyepiece lenses 4, 4 may be provided in the eyepiece tube 2. However, there is no change in its effectiveness.

[Effects of the Invention] As explained above, in the cryogenic fiberscope of the present invention, the inside of the objective lens barrel is in a reduced pressure state, both ends of which are sealed with transparent windows, and the above-mentioned image transmitting body is placed in one of the windows. or the inside of the objective lens barrel is filled with a gas with a boiling point lower than that of the cryogenic medium in which the objective lens barrel is immersed, and both ends are sealed with transparent windows, and one side of this window is sealed. Since the above-mentioned image transmitting bodies are connected in a butt-to-edge state, there is no condensation on the objective lens or the end face of the image transmitting body when used immersed in a cryogenic medium, and a stable image can be obtained. You can always get it. Furthermore, since a suction device unlike conventional ones is not required, operability during observation is improved, and stable images can be obtained over a long period of time, improving reliability. Further, since a suction device is not required, miniaturization is possible. Furthermore, since the image transmitting body does not pass through the window of the objective mirror, the structure of the connecting portion between the objective lens barrel and the image transmitting body is simple, and a high level of liquid tightness is maintained. Furthermore, since only the objective lens barrel 9 can be replaced easily, maintainability is also improved.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the cryogenic fiberscope of the present invention, and FIG. 2 is a schematic configuration diagram showing an example of a conventional cryogenic fiberscope. DESCRIPTION OF SYMBOLS 1... Image transmission body, 2... Eyepiece tube, 4... Eyepiece lens, 7... Objective lens, 8... Window, 9...
Objective lens barrel, L...cryogenic medium.

Claims (1)

[Scope of Claims] 1. An eyepiece tube provided with an eyepiece lens, an objective lens tube provided with an objective lens, and an image transmission body that transmits an image obtained with the objective lens tube to the eyepiece tube. A fiberscope for cryogenic use, characterized in that the inside of the objective lens barrel is in a reduced pressure state, both ends of which are sealed with transparent windows, and the image transmitting body is connected to one of the windows in a butt state. Fiberscope for cryogenic temperatures. 2. A cryogenic fiber consisting of an eyepiece tube equipped with an eyepiece, an objective tube equipped with an objective lens, and an image transmission body that transmits an image obtained with this objective tube to the eyepiece tube. The objective lens barrel is filled with a gas having a boiling point lower than that of the cryogenic medium in which the objective lens barrel is immersed, and both ends of the objective lens barrel are sealed with transparent windows, and one of the windows is provided with the above-mentioned image. A fiberscope for cryogenic temperatures that features transmitters connected in a butt-to-edge manner.