JP2000275175A - Optical fiber cell for measuring solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the absorbancy of a soln. without lowering the light receiving intensity of a measuring instrument by providing a light path capable of reflecting as many parts as possible of the light emitted from a first light receiving optical fiber without enlarging the whole of a cell. SOLUTION: A light receiving optical fiber is constituted of first and second light receiving optical fibers 31, 32 and a refractive index invariable space 33 is provided on the extension of the first and second light receiving optical fibers 31, 32 and a concave mirror 9 gathering the light emitted from the first light receiving optical fiber 31 to the second light receiving optical fiber 32 is arranged to the space 33 and oblique cutting is applied to the emitting end surface 31a of the first light receiving optical fiber 31 and the incident end surface 32a of the second light receiving optical fiber 32 in order to turn the optical axes of both optical fibers to the concave mirror 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cell for measuring a solution in which a light emitting end of a light emitting optical fiber and a light receiving end of a light receiving optical fiber are put into a solution and absorbance of the solution is measured.

[0002]

2. Description of the Related Art An optical fiber cell for measuring a solution has a space in which a solution can enter, in which an optical fiber for projecting light and an optical fiber for receiving light are fixed, and the absorbance of the solution interposed therebetween is measured. FIG. 8 shows the structure of a conventional optical fiber cell for solution measurement. In the optical fiber cell for solution measurement, an optical fiber for light emission 45 and an optical fiber for light reception 46 are held by metal fittings 44 and are fixed in a rectangular parallelepiped cell 41. The middle part of the cell 41 is hollow, and the solution 49 enters the hollow part through the window.

A concave mirror 47 is provided at the tip of the cell 41, and the end faces of the optical fibers 45 and 46 face the concave mirror 47 via the hollow portion. When the entire optical fiber cell for solution measurement is immersed in the solution 49 and light of a certain wavelength is passed through the optical fiber 45 for light emission, the light is irradiated into the solution 49 from the end face of the optical fiber 45 for light emission, and the concave mirror 4
The light is reflected by the optical fiber 7 and enters the light receiving optical fiber 46 from the end face of the light receiving optical fiber, and the light receiving intensity is measured by a measuring instrument (not shown).

[0004]

In the above measurement, the optical axis 451 of the light emitting optical fiber 45 is directed right below in FIG.
Also face directly below in FIG. The center position 471 of the concave mirror 47 is located between the two optical axes 451 and 461.

Accordingly, the light 4 on the optical axis having the largest light quantity
51 is reflected in an irrelevant direction that does not enter the light receiving optical fiber 46 even if it hits the concave mirror 47,
The light that strikes the center position 471 of the concave mirror 47 and enters the light receiving optical fiber 46 is transmitted through the light projecting optical fiber 4.
5 is only a part 452 of the light emitted from 5. For this reason, there has been a problem that the light receiving intensity of the measuring instrument is reduced and the noise is relatively increased, so that the absorbance of the original solution cannot be measured accurately.

In order to solve such a problem, it is necessary to increase the distance between the optical fibers 45 and 46 and the concave mirror 47 and increase the mirror surface area of the concave mirror 47. In this case, the entire optical fiber cell for solution measurement is made. And another problem arises in that a large amount of solution is required. Therefore, an object of the present invention is to realize a solution-measuring optical fiber cell capable of folding back as much of the light projected from the light projecting optical fiber 45 as possible without increasing the overall size.

[0007]

In the optical fiber cell for solution measurement of the present invention, the light receiving optical fiber is constituted by first and second light receiving optical fibers, and the first light receiving optical fiber and the second light receiving optical fiber are connected to each other. A space where the refractive index does not change is provided on the extension of the light receiving member, and a light collecting member for collecting light emitted from the first light receiving optical fiber to the second light receiving optical fiber is provided in this space, and the first light receiving member is provided. At least one of the outgoing end face of the optical fiber and the incoming end face of the second light receiving optical fiber is provided with a means for directing the optical axis to the light collecting member.

According to the above construction, a space having a constant refractive index is provided in an extension of the first light receiving optical fiber and the second light receiving optical fiber, and a light collecting member is provided in this space, and the first light receiving light fiber is provided. A means for directing the optical axis to the light-collecting member is provided on one or both of the output end face of the optical fiber and the input end face of the second light-receiving optical fiber. Most of the emitted light is collected and incident on the incident end face of the second light receiving optical fiber. For this reason, unnecessary diffusion of light is prevented and loss is reduced.

The reason why the "space with invariable refractive index" is provided is that the light path of the light emitted from the emission end of the first light receiving optical fiber and the light path of the light incident on the incident end face of the second light receiving optical fiber are different. This is because the temperature does not change due to replacement of the solution, temperature change, or turbulence. Specifically, it is an air chamber, glass, transparent resin, or the like. The “light-collecting member”
Is a curved mirror, a lens, or the like. The "means for directing the optical axis to the light condensing member" includes means for obliquely cutting the end face, covering a small prism on the end face, and bending the tip of an optical fiber connected to the end face.

The light emitting optical fiber and the light receiving optical fiber may be interchanged. Also,
A relay optical fiber held by a holding member is installed between a light emitting end of the light emitting optical fiber and a light receiving end of the light receiving optical fiber, and the relay optical fiber is constituted by first and second relay optical fibers. A space in which the refractive index does not change is provided on an extension of the relay optical fiber, and a light collecting member that collects light emitted from the first relay optical fiber to the second relay optical fiber is provided in this space; A means for directing an optical axis to the light-collecting member may be provided on one or both of the output end face of the first relay optical fiber and the input end face of the second relay optical fiber. ).

With this configuration, measurement can be performed between the light emitting end of the light emitting optical fiber and one end of the relay optical fiber, and between the light receiving end of the light receiving optical fiber and one end of the relay optical fiber. In addition, the measuring optical path can be made longer as a whole. Providing the means for directing the optical axis has the same effect as reducing the loss of light, as described above.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment FIG. 1A is a side sectional view of an optical fiber cell for solution measurement, and FIG. 1B is a front view of the optical fiber cell for solution measurement.
The optical fiber cell for solution measurement includes a light projecting end 2 a of the light projecting optical fiber 2 and a light receiving end 3 a of the light receiving optical fiber 3.
a is placed in a solution, and the absorbance of the solution is measured.
May be a single optical fiber, or may be an integrated image guide having a plurality of cores.

The optical fiber cell for solution measurement has a first holder 4 for holding the light projecting optical fiber 2 through the hole and a second holder 5 for holding the light receiving optical fiber 3 through the hole. are doing. The first holder 4 and the second holder 5 are partially connected, and a space 1 for introducing a solution is formed therebetween. In addition, the material of the first holder 4 and the second holder 5 is not particularly limited, and may be any material such as a metal and a polymer resin. Light emitting optical fiber 2
Is projected from the first holder 4 by the length L1, and the coating of the optical fiber is peeled off. The light receiving end 3a of the light receiving optical fiber 3 is also
From the holder 5 and the coating of the optical fiber is peeled off. Note that only the coating of the optical fiber at least near the end face of the light emitting end 2a and the light receiving end 3a may be peeled off.

The end face of the optical fiber is optically polished. FIG. 2 is a diagram for explaining a method of optically polishing the end face of the optical fiber 20 before being held by the first holder 4 and the second holder 5. Optical fiber 2
0, one by one or in a bundle with the coating 22 attached, slightly projecting from the end face of the collet chuck 23, chucking the collet chuck 23, and polishing the end face 24 of the optical fiber 20 together with the end face of the collet chuck 23. I do. Some dripping occurs around the end face 24 of the optical fiber 20, but there is no problem if the dripping does not reach the core.

After polishing, the coating 22 has a predetermined length at the tip.
Is removed to expose the cladding (there is a core at the center) 21, and a corner formed by the end face and the side face of the optical fiber is slightly chamfered or rounded. Chamfering is performed around the entire circumference using a special jig. The rounding can be performed, for example, by treating the tip with hydrofluoric acid. Then, it is inserted into the through hole of the first holder 4 or the second holder 5 and adhered and held.

By the above-described end face treatment, all portions of the optical fiber that come into contact with the solution become smooth. Therefore, there is no adhesion of dirt and dust, and it is possible to prevent air bubbles from adhering. If the protruding amounts L1 and L2 of the tip of the optical fiber are too short, the tip may be covered with large bubbles. When the entire optical fiber cell for solution measurement is put in water left at room temperature (25 ° C.) and the temperature is raised to 37 ° C., a protrusion amount of 1 mm is necessary so that the tip is not covered with large bubbles. Was.

In FIG. 1, there is no condensing lens between the light projecting end 2a of the light projecting optical fiber 2 and the light receiving end 3a of the light receiving optical fiber 3; If the distance between the end 2a and the light receiving end 3a is reduced and the core diameter of the optical fiber is increased to some extent, a part of the light of the light projecting optical fiber 2 enters the light receiving optical fiber 3 with sufficiently detectable intensity. If a condensing lens is provided,
The distance between the light emitting end 2a and the light receiving end 3a can be increased, and the core diameter of the optical fiber can be reduced.

FIG. 3 shows the light projecting end 2 of the light projecting optical fiber 2.
a between the light receiving end 3a of the light receiving optical fiber 3 and the light receiving end 3a.
FIG. 4 is a cross-sectional view of a main part of a solution measurement optical fiber cell in which a relay optical fiber 7 held by a holder 8 is installed.
The relay optical fiber 7 is folded back into a U-shape, and both ends 7a and 7b protrude from the third holder 8, and the coating of the relay optical fiber 7 is peeled off at the tip of the protrusion.

Therefore, measurement is performed between the light projecting end 2a of the light projecting optical fiber 2 and one end 7a of the relay optical fiber 7, and between the light receiving end 3a of the light receiving optical fiber 3 and one end 7b of the relay optical fiber 7. The measurement optical path can be made longer as a whole. -Second Embodiment-Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4 is a side sectional view of an optical fiber cell for solution measurement according to a second embodiment. In this example, the light receiving optical fibers 3 are optically connected in series (hereinafter, simply referred to as “serial”), and the space between the first and second light receiving optical fibers 31 and 32 (in extension). An air chamber 33 having a concave mirror 9 for collecting light emitted from the first light receiving optical fiber 31 to the second light receiving optical fiber 32 is provided in the space (2). 10 is an air hole.
The concave surface of the concave mirror 9 is originally an elliptical surface, but may be a spherical surface.

Opposite end faces 31a, 32a of first and second light receiving optical fibers 31, 32 formed in series.
Are cut diagonally to bend the light. The angle of this cut is determined by the end face 3 of the first light receiving optical fiber 31.
The light beam refracted by 1a is determined so as to impinge on a substantially central portion of the concave mirror 9 and to be reflected on the end face 32a of the second light receiving optical fiber 32.

FIG. 5A is a side sectional view showing a main part of the optical fiber cell for solution measurement, and FIG. 5B is a bottom view of the second holder 5. The angle of the bottom surface 5a of the holder 5 is determined by the end surfaces 31a, 32 of the first and second light receiving optical fibers 31, 32.
It is adjusted to the cut angle of a. Therefore, this first,
End faces 31a, 3 of second light receiving optical fibers 31, 32
In order to cut 2a obliquely, the first and second light-receiving optical fibers 31, 32 are mounted on the second holder 5, and the bottom surface 5a of the holder 5 is optically polished with the tip thereof slightly extended.

The first and second light receiving optical fibers 3
Since the space between 1 and 32 needs to be filled with a substance having a constant optical refractive index, air is introduced in this example.
However, as long as the substance has a constant refractive index, the substance is not limited to air, but may be water, for example, or may be sealed with a transparent resin such as an acrylic resin. According to the optical fiber cell for solution measurement, the concave mirror 9 is different from that of the first embodiment.
Since the light is reflected by the optical fiber, the distance between the light emitting optical fiber 2 and the second light receiving optical fiber 32 can be reduced. Therefore, the optical fiber cell for solution measurement can be made elongated, and a small container can be used as a container for holding the solution.

The first and second light receiving optical fibers 3
Due to the oblique cut of the end faces 31a and 32a of the first and second end faces 32 and the condensing action of the concave mirror 9, the first light receiving optical fiber 31 is provided.
Can be made incident on the end face 32a of the second light receiving optical fiber 32 without losing most of the light emitted. FIG. 6 shows a convex lens 91 and a plane mirror 9 in place of the concave mirror 9.
It is a figure showing the combination of 2. Even with the combination of the convex lens 91 and the plane mirror 92, a light collecting action can be realized as in the case of the concave mirror 9.

FIG. 7 shows a configuration in which two relay optical fibers 7 are arranged in series, and the space between the first and second relay optical fibers 71 and 72 formed in series is the first relay optical fiber 7. FIG. 9 is a cross-sectional view showing a solution measurement optical fiber cell provided with a concave mirror 9 for collecting light emitted from the optical fiber 71 to a second relay optical fiber 72. FIG. 7 shows a measurement state in which the entire optical fiber cell for solution measurement is attached to the solution 39.

The facing end faces 7c, 7d of the first and second relay optical fibers 71, 72 formed in series are obliquely cut to bend light. The light emitted from the end face 7c of the first relay optical fiber 71 collides with a predetermined portion of the concave mirror 9, is reflected, and is incident on the end face 7d of the second relay optical fiber 72. The first and second
Since the space between the relay optical fibers 71 and 72 needs to be filled with a substance having a constant optical refractive index, air is filled in this example. However, as long as the substance has a constant refractive index, the substance is not limited to air, but may be water, for example, or may be sealed with a transparent resin such as an acrylic resin.

According to the optical fiber cell for solution measurement, since the light is reflected by the concave mirror 9, the distance between the light emitting optical fiber 2 and the light receiving optical fiber 3 can be reduced. Therefore, a thin container can be used as the container 40 for the solution 39. Although the embodiment of the present invention is as described above, the embodiment of the present invention is not limited to the above embodiment. For example, even if the light emitting side and the light receiving side are exchanged, the same operation and effect can be obtained. Can be In addition, various changes can be made within the scope of the present invention.

FIG. 9 is a diagram showing another structure of the optical fiber cell for solution measurement. First light receiving optical fiber 51
A convex lens 53 having both a condensing function and a function of bending the optical axis is disposed on both end faces of the second light receiving optical fiber 52. , First light receiving optical fiber 51
There is provided a plane mirror 54 for reflecting light emitted from the lens and passing through the convex lens 53.

Even with this structure, most of the light emitted from the emission end of the first light receiving optical fiber 51 is condensed and incident on the incident end face of the second light receiving optical fiber 52. Light loss is reduced. Further, even if the light emitting side and the light receiving side are switched, the same operation and effect can be obtained.

[0030]

As described above, according to the optical fiber cell for solution measurement of the present invention, it is possible to provide an optical path which can return as much of the light entering the solution as possible without increasing the size of the entire cell. Therefore, the absorbance of the original solution can be accurately measured without reducing the light receiving intensity of the measuring instrument.

[Brief description of the drawings]

FIG. 1A is a side sectional view of an optical fiber cell for solution measurement according to a first embodiment, and FIG. 1B is a front view.

FIG. 2 is a diagram for explaining a method of optically polishing an end face of an optical fiber.

3 shows a third holder 8 between a light emitting end 2a of the light emitting optical fiber 2 and a light receiving end 3a of the light receiving optical fiber 3. FIG.
FIG. 5 is a cross-sectional view of a main part of a solution-measuring optical fiber cell in which a relay optical fiber 7 held by the apparatus is installed.

FIG. 4 is a side sectional view of an optical fiber cell for solution measurement according to a second embodiment of the present invention.

5A is a side sectional view showing a main part of an optical fiber cell for solution measurement, and FIG. 5B is a bottom view of a second holder 5. FIG.

FIG. 6 is a diagram showing a combination of a convex lens 91 and a plane mirror 92 in place of the concave mirror 9;

FIG. 7 shows two relay optical fibers 7 connected in series,
FIG. 4 is a cross-sectional view showing a solution measurement optical fiber cell provided with a concave mirror 9 for collecting light emitted from the relay optical fiber 71 into the relay optical fiber 72 in a space between the serially configured relay optical fibers 71 and 72. .

FIG. 8 is a structural view of a conventional optical fiber cell for solution measurement.

FIG. 9 is a diagram showing another structure of the optical fiber cell for solution measurement.

[Explanation of symbols]

 Reference Signs List 1 space 2 light emitting optical fiber 2a light emitting end 3,31,32 light receiving optical fiber 3a light receiving end 31a, 32a end face of light receiving optical fiber 31,32 4 first holder 5 second holder 5a bottom surface of second holder 7, 71, 72 Relay optical fiber 7a, 7b Relay optical fiber end 7c, 7d Relay optical fiber end face 8 Third holder 9 Concave mirror

Claims (3)

[Claims] 1. A solution measuring optical fiber cell for measuring the absorbance of a solution by placing a light emitting end of a light emitting optical fiber and a light receiving end of a light receiving optical fiber in a solution, wherein the light receiving optical fiber is first and second. A light-receiving optical fiber, a space having a constant refractive index is provided on an extension of the first light-receiving optical fiber and the second light-receiving optical fiber, and the light emitted from the first light-receiving optical fiber is provided in the second space. A light-collecting member for condensing light on the light-receiving optical fiber is installed. Either or both of the output end face of the first light-receiving optical fiber and the incident end face of the second light-receiving optical fiber are provided with an optical axis on the light-collecting member. An optical fiber cell for measuring a solution, wherein a means for directing the solution is provided. 2. A solution measuring optical fiber cell for measuring the absorbance of a solution by inserting a light emitting end of a light emitting optical fiber and a light receiving end of a light receiving optical fiber into a solution. A space having a constant refractive index is provided on an extension of the first light emitting optical fiber and the second light emitting optical fiber, and the light is emitted from the first light emitting optical fiber in this space. A light-collecting member for condensing the obtained light on the second light-projecting optical fiber is provided, and one or both of the light-emitting end face of the first light-projecting optical fiber and the light-entering end face of the second light-projecting optical fiber. An optical fiber cell for measuring a solution, wherein a means for directing an optical axis to the light-collecting member is provided. 3. A solution-measuring optical fiber cell for measuring the absorbance of a solution by inserting a light-emitting end of a light-emitting optical fiber and a light-receiving end of a light-receiving optical fiber into a solution. A relay optical fiber held by a holding member is provided between the light receiving end of the light receiving optical fiber and the light receiving end of the light receiving optical fiber.
It is composed of a second relay optical fiber, a space having a constant refractive index is provided on an extension of the relay optical fiber, and light emitted from the first relay optical fiber is condensed on the second relay optical fiber in this space. A light-collecting member is provided, and a means for directing an optical axis to the light-collecting member is provided on one or both of the output end face of the first relay optical fiber and the input end face of the second relay optical fiber. An optical fiber cell for measuring a solution, comprising: