JPS61267014A - Cryogenic fiber scope - Google Patents

Abstract

PURPOSE:To prevent water from being frozen and condensed by providing an optical lens barrel which supports objectives with a means which makes a communication between the inside and outside of the optical lens barrel supports objectives. CONSTITUTION:The optical lens barrel 20 is formed merely in a cylindrical shape and plural through holes 23-26 are formed in its peripheral wall at the position between the end surface of an image guide 19 and the objective 21, and the objective 21 and objective 22, and a position under the objective 22. Consequently, either air nor vapor is present at the peripheries of the objectives 21 and 22 and freezing and dew condensation on the end surface 17a of the optical fiber bundle 17 and surfaces of the objectives 21 and 22 which easily occur when the fiber scope is cooled to extremely low temperature are not caused at all.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a cryogenic fiberscope.

In particular, the present invention relates to a cryogenic fiberscope that can prevent condensation or dew condensation on the end face of a fiber bundle, the surface of an objective lens, etc.

[Technical background of the invention and its problems]

Liquefied natural gas, liquefied propane gas, liquid nitrogen.

When constructing cryogenic IIi facilities that handle liquid helium, etc., it is necessary to confirm through experiments the behavior of the materials used to construct these facilities at extremely low temperatures. During such experiments, it is also important to visually observe the state of materials kept at extremely low temperatures.

Generally, the easiest way to maintain materials at extremely low temperatures is to immerse them in the extremely low concentration liquid described above. If such a method is adopted.

The sample cannot be observed directly with the naked eye. Therefore, it may be possible to observe using a fiberscope.

However, when a normal temperature fiberscope is used, condensation or dew condensation occurs on the end face of the fiber bundle, the optical window, and the surface of the objective lens, making it difficult to observe well.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and its purpose is to prevent condensation and dew condensation on the end face of the fiber bundle, the surface of the objective lens, etc. An object of the present invention is to provide a fiberscope for cryogenic use that allows good observation of the state of substances in the environment.

[Summary of the invention]

According to the present invention, there is provided a cryogenic fiber scope in which an optical barrel supporting an objective lens is provided with means for communicating the inside and outside of the optical barrel. More specifically, the above-mentioned means are realized by holes formed in the optical barrel.

〔Effect of the invention〕

According to the invention, the space in which the objective lens is located communicates with the outside. Therefore, even if air or water vapor exists in the above space, as soon as the objective lens is inserted into the cryogenic liquid, all of this air and water vapor will be pushed out by the cryogenic liquid that has flowed into the optical barrel. It will be done. Condensation or dew condensation on the surface of an objective lens is usually caused by air or water vapor present in the space in which the objective lens is located. However, in the present invention, the air and water vapor existing in the space are removed, so the above-mentioned condensation and dew condensation do not occur. Therefore, it can contribute to realizing good observation.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram when a sample kept at a cryogenic temperature is observed using a cryogenic fiberscope according to an embodiment of the present invention.

That is, in FIG. 1, numeral 1 indicates a cryostat containing liquid helium H, which is a cryogenic liquid, and numeral 2 indicates a sample accommodated within the cryostat 1.

A cryogenic fiberscope 11 according to the present invention is installed through the upper wall of the cryostat 1. The cryogenic fiber scope 11 is broadly divided into an illumination system 12 that irradiates light toward the sample 2, and an image transmission system 13 that transmits an image of the sample 2.

Is lighting system 12 light? Filter 1 for the light emitted from l114
5, the infrared rays are cut by this filter 15, and this infrared rays cut light is introduced into one end of a light guide 16. The other end of the light guide 16 extends through the earthen wall of the cryostat 1 to the vicinity of the sample 2, and is arranged so as to irradiate the upper surface of the sample 2 with the introduced light. On the other hand, the image transmission system 13 is specifically constructed as shown in FIG. That is, an optical lens barrel 20 is coaxially connected to one end of an image guide 19 consisting of an optical fiber bundle 17 and a flexible cladding tube 18 that covers the optical fiber bundle 17. In the optical barrel 20, objective lenses 21 and 22 are arranged, for example, in a two-stage configuration.
．． The peripheral edge of the optical lens barrel 22 is fixed to the inner peripheral surface of the optical lens barrel 20 using an adhesive or mechanical means that does not deteriorate in function even at extremely low temperatures.

The optical lens barrel 20 is formed into a simple cylindrical shape.

The end surface of the image guide 19 and the objective lens 21 are connected to the peripheral wall thereof.
The part located between the objective lens 21 and the objective lens 2
Through-holes 23, 24, 2! 5', 26 are provided in the portion located between the objective lens 22 and the portion located below the objective lens 22 in the figure.
A plurality of each are provided along the circumferential direction.

Further, an eyepiece lens 27 is attached to the other end of the image guide 19, as shown in FIG. In the image transmission system 13 configured in this way, the optical barrel 20 side is inserted into the cryostat 1, as shown in FIG. 1, and the objective lens 22 is arranged so as to be close to the upper surface of the sample 2. .

The following procedure is used to observe the sample 2 housed in the cryostat 1 using the cryogenic fiberscope configured as described above. First, the sample 2 is placed in the cryostat 1, and then the illumination system 12 and image transmission system 13 are placed as shown in FIG. Next, the piping 28
Connect it to a vacuum pump and evacuate the inside of the cryostat 1. When the evacuation is completed, helium gas is first introduced through the pipe 29, and then liquid helium H is introduced into the cryostat 1 to a predetermined level.

In this way, when liquid helium H is introduced into the cryostat 1, a portion of the liquid helium passes through the through holes 23, 24, 25° 26 provided in the wall of the optical lens barrel 20, and enters the optical lens barrel '20. It flows into the interior and eventually becomes full. Therefore, air and water vapor existing within the optical barrel 20 are forced out of the optical barrel 20. Then, when the liquid helium H reaches a predetermined level, the supply of liquid helium is stopped, and then the pressure inside the cryostat 1 is reduced to a certain value through the pipe 28. This reduced pressure removes air bubbles attached to the surfaces of the objective lenses 21, 22, etc. After removing the bubbles, helium gas is introduced to return the pressure to 1 atmosphere.

When such operations are completed, by turning on the light source 14 and observing the sample 2 through the eyepiece 27, the behavior of the sample 2 at extremely low temperatures can be visually confirmed.

In this case, the inside of the optical mirror lm20, that is, the objective lens 21.
Since there is no air or water vapor around the optical fiber bundle 17, the end face 17a of the optical fiber bundle 17 and the objective lens 21.
No condensation or condensation occurs on the surface. therefore,
Sample 2 can be observed well, and the above-mentioned effects can be achieved after all. As is clear from the above explanation.

When this cryogenic fiberscope is actually used, a liquid helium layer is interposed between the end face of the optical fiber bundle 17 and the objective lens 21 and between the objective lens 21 and the objective lens 22. Become. Therefore, it is of course necessary to set the dimensions of each part taking into consideration the refractive index of the liquid helium layer interposed between the parts.

Note that the present invention is not limited to the above embodiments.

For example, the number of objective lenses is not limited to the number in the embodiment. Other 9 It goes without saying that modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram when a cryogenic fiberscope according to an embodiment of the present invention is actually installed. FIG. 2 is a longitudinal cross-sectional view of the essential parts of the cryogenic fiberscope. 1... Cryostat, 2... Sample, 12...
Lighting system. 13... Image transmission system, 14... Light source, 15... Filter, 16... Light guide, 19... Image guide. 20... Optical lens barrel, 21.22... Objective lens, 2
3゜24.25.26...hole, 27...eyepiece, H...liquid helium.

Claims (2)

[Claims] (1) A fiberscope for cryogenic use, characterized in that an optical barrel that supports an objective lens is provided with means for communicating the inside and outside of the optical barrel. (2) The cryogenic fiberscope according to claim 1, wherein the means for communicating between the inside and the outside is a hole formed in the optical lens barrel.