JPH08240484A - Infrared spectrum measuring device and optical fiber probe to constitute infrared spectrum measuring device and manufacture of optical fiber probe - Google Patents

Abstract

PURPOSE: To provide an infrared spectrum measuring device in which the infrared light excellently propagates and whose handling is easy. CONSTITUTION: Optical fiber 4 to be connected to an infrared spectrum measuring part 1 is composed of optical fiber propagating parts 5 and 5 on both ends and the optical fiber probe 6 in the center, and this optical fiber probe 6 and the optical fiber propagating parts 5 and 5 are made separable from and joinable to each other by respective connectors 7 and 7. A clad of a central part of the optical fiber probe 6 is removed, and a core is exposed, and a measuring sample S is stuck to this exposed part, and absorption of a spectrum is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared spectrum measuring apparatus which has good infrared light propagation and is easy to handle in infrared spectrum measurement, and an optical fiber probe applied to this infrared spectrum measuring apparatus. The present invention relates to a method for manufacturing an optical fiber probe.

[0002]

2. Description of the Related Art The light having a wavelength peculiar to the substance is absorbed after passing through or reflecting the substance. Therefore, it is possible to perform quantitative and qualitative analysis by irradiating a substance with light and performing spectrum analysis. However, for example, when infrared light having a wavelength of 2 to 11 μm is used, vibration between atoms included in a molecule and rotation of the entire molecule. You can get unique spectral information about
By analyzing this, not only simple quantitative and qualitative analysis but also the structure and state of the substance can be known.

One of the methods for measuring the infrared absorption spectrum is the ATR (Attenuated Total Reflection) method. This ATR method is as shown in FIG. 7, which is a principle diagram,
The measurement sample S is brought into close contact with the surface of a prism 50 made of a high-refractive index material that transmits infrared light, and incident light 51 that is incident on the prism 50 at an incident angle equal to or greater than the critical angle is reflected by the prism 5
0 and the measurement sample S are totally reflected at the interface, and then propagated light 5
2 is measured to obtain an infrared absorption spectrum.

By the way, in such an ATR method, since the prism 50 functions as a probe, the sensitivity increases as the number of total reflections in the prism 50 increases. Therefore, it is necessary to use the large prism 50 in order to improve the measurement accuracy, but the high refractive index material used for the prism 50 is expensive, and precise prism processing is also difficult. In addition, for example, when measuring the curing reaction process of a polymer substance such as an adhesive, it is necessary to peel the cured polymer substance from the prism 50 after the measurement is completed, but it is difficult to peel depending on the cured substance. In some cases, the prism 50 may be damaged by attempting to peel it off. Further, in order to guide the incident light 51 from the light source to the prism 50 and the propagating light 52 from the prism 50 to the measuring device, a complicated optical system is required.

Therefore, a method of applying the principle of the ATR method to an optical fiber and using the optical fiber itself as a probe has been studied and reported (James A. de Haseth Jennifer EA).
ndrews, John V. Mcclusky, Ralph D. Priester, Jr., Mat
thew A. Harthcok and L. Davis: APPLIED SPECTROSCOPY,
Vol.47, No.2, (173) 1993 or Mark A. Druy, LucyEl
andjian, WAStevenson SPIE Vol 986 Fiber Optics S
mart Structure and Skins (130) 1988 etc.). Explaining the principle of this method with reference to FIG. 8, the incident light 51 incident on the optical fiber propagates while being totally reflected at the interface between the core 53 and the clad 54. Therefore, the clad 54 is removed from a part of the optical fiber to expose the core 53 of the same portion, and the measurement sample S is attached to the outer periphery of the exposed core 53 so that the probe 55 is provided near the same portion. Then, the incident light 51 propagates while being totally reflected at the interface between the core 53 of the probe 55 and the measurement sample S. Then, if this propagating light 52 is measured, an infrared spectrum can be obtained similarly to the ATR method.

Here, since the exposed portion of the core 53 functions as a probe, the longer the exposed portion, the better the sensitivity. In this respect, the exposed portion of the optical fiber can be easily and inexpensively lengthened, and it is easy to increase the number of total reflections and improve the sensitivity. Further, since there is no need for precise prism processing, and since the fiber can be directly connected to the light source, the measuring device, etc. by utilizing the characteristics of the optical fiber, there is an advantage that a complicated optical system is not required. The drawbacks of can be improved.

[0007]

However, the core 53 portion exposed as the probe 55 as described above has a very weak strength, and the longer the exposed portion is to increase the sensitivity, the more the handling of the optical fiber becomes difficult. There was a problem that it would be difficult. In addition, since the probe 55 is formed on a part of one optical fiber, if the probe 55 is damaged during handling, the entire optical fiber must be discarded, which is a factor of cost increase. There was also the problem of becoming.

Further, for example, in the case of measuring the curing reaction process of a polymer substance, even if the cured substance is tried to be peeled from the probe 55 after the measurement, the work of peeling it from the prism 50 or the like because the outer diameter of the optical fiber is thin. It will be several steps harder than. In addition, if this optical fiber is attempted to work while being bonded to a light source or a measuring device, it takes much more work. On the other hand, when the optical fiber is, for example, a chalcogenide glass fiber, a means for removing a part of the clad glass has not been known.

[0009]

SUMMARY OF THE INVENTION Therefore, the present invention provides an infrared absorption spectrum device capable of favorably propagating infrared light and not wasting an expensive optical fiber. According to the invention of claim 1, in an infrared spectrum measuring device comprising an infrared spectroscopic measuring section and an optical fiber in which a part of the optical fiber propagating section is used as an optical fiber probe, the optical fiber probe and the optical fiber propagating section can be separated and joined. did.

According to the second aspect of the invention, the infrared spectroscopic measurement section includes a light source, a grating, a photodetector, and
It consisted of a coupler connected to an optical fiber.

According to the third aspect of the invention, the infrared spectroscopic measuring section includes a light source, an interferometer for measuring the difference between the measuring light and the reference light, a photodetecting section, and a coupler connected to the optical fiber. It was composed of a Fourier transform infrared spectrophotometer.

According to a fourth aspect of the present invention, the connector for separating and joining the optical fiber probe and the optical fiber propagating portion is a ferrule which holds the tip of the optical fiber and has an external thread and an outer peripheral taper. A cylindrical fixing member that allows the tip of the ferrule to be inserted and that has an internal thread and an engaging flange on the inner surface and a part of this tapered guide tube to be inserted, and has an inner peripheral taper on the outer surface. It is composed of a tapered guide tube having an engaging projection.

In the invention of claim 5, the optical fiber is a chalcogenide glass fiber.

A sixth aspect of the present invention relates to an optical fiber probe in which the clad at the central portion of the optical fiber is removed and both ends of the optical fiber are detachably attached to the optical fiber propagating section by the connector of the fourth aspect. The invention of claim 7 relates to a method for producing an optical fiber probe, wherein the clad glass in the central portion of the optical fiber is immersed in an alkaline solution and removed to form an optical fiber probe.

[0015]

In the infrared spectrum measuring device using a part of the optical fiber propagation part as the optical fiber probe, the optical fiber propagation part and the optical fiber probe can be separated and joined so that only the optical fiber probe is required. Remove it,
It is possible to perform work, replacement, etc., for example, work for removing the cured polymer substance is facilitated, or the expensive optical fiber propagation section is not wastefully discarded.

As the separating and joining means, a connector comprising a ferrule, a tapered guide tube and a fixing member is provided, the tip of the ferrule holding the optical fiber is inserted into the tapered guide tube, and a female screw of the outer fixing member is provided. By engaging the male thread of the ferrule with the engaging flange of the fixing member and the engaging projection of the tapered guide tube, the outer peripheral taper of the ferrule and the inner peripheral taper of the tapered guide tube are closely contacted, Connect with the optical axes aligned.

As an infrared spectroscopic measurement unit, a light source,
Fourier transform red consisting of a grating, a photodetector, a coupler connected to the optical fiber, or a light source, an interferometer for measuring the difference between the measurement light and the reference light, a photodetector, and a coupler connected to the optical fiber. The infrared spectrophotometer can be easily measured by using an external spectrophotometer. Further, if a chalcogenide glass fiber is used as the optical fiber, the propagation of infrared light in the infrared region becomes good.

Further, when removing the cladding glass at the center of the optical fiber, if the same is immersed in an alkaline solution,
The clad glass of the chalcogenide glass fiber can be easily removed.

[0019]

Embodiments of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is a schematic configuration diagram of a first embodiment of an infrared spectrum measuring apparatus of the present invention, FIG. 2 is an enlarged view of a connector, and FIG. 3 is a graph showing a result of measuring distilled water using this apparatus. . As shown in FIG. 1, the infrared spectrum measuring apparatus of the present invention includes an infrared spectroscopic measurement unit 1 including a light source 2 and a spectroscope 3, and an optical fiber 4 connecting the light source 2 and the spectroscope 3.
The optical fiber 4 comprises optical fiber propagating portions 5 and 5 at both ends and an optical fiber probe 6 at the central portion. Then, both ends of the optical fiber probe 6 are respectively connected to the optical fiber propagating portions 5 and 5, respectively.
Are combined so that the optical axes coincide with each other.

The light source 2 is an infrared generator 2a such as an infrared lamp which emits infrared rays containing a wavelength component of 2 to 11 μm.
And a coupler 2b for connecting the emitting part of the infrared ray generating part 2a and the optical fiber propagating part 5 to each other.
An optical system 2c for incorporating the light emitted from the emitting portion into the optical fiber propagation portion 5 as measurement light is built in.

As shown in FIG. 2, the connector 7 has ferrules 8 and 8 for holding the tip of the fiber, and a cylindrical guide tube 9 into which the tip of the ferrules 8 and 8 can be inserted. An outer peripheral taper 8a is formed on the outer surface of the ferrule 8 on the distal end side, which is composed of cylindrical fixing members 10 and 10 which are inserted through both ends of the tapered guide tube 9.
And a male screw 8b is provided on the outer surface of the base end side. Further, inner tapers 9a, 9a corresponding to the outer taper 8a of the ferrule 8 are provided on the inner surfaces of both ends of the tapered guide tube 9, and the engaging projections 9b, 9b are provided on the outer surfaces of both ends. Is provided. Further, an engagement flange 10a engageable with the engagement protrusion 9b is provided on the inner surface of one end of the fixing member 10, and a female screw 10b is provided on the inner surface of the other end.

Then, the front end portions of the ferrules 8 and 8 are inserted from the opening portions at both ends of the tapered guide tube 9, and the female screws 10b and 10b of the respective fixing members 10 and 10 are inserted into the male screws 8b and 8b of the respective ferrules 8 and 8. The outer peripheral taper 8a and the outer peripheral taper 8a are brought into close contact with the respective inner peripheral taper 9a and 9a by being screwed into the optical fiber so that they can be coupled with the optical axes of the both fibers aligned.

The spectroscope 3 includes a coupler 3a for connecting to the optical fiber propagation section 5, a grading 3b for splitting the introduced light, a photodetector 3c for detecting the split light, and this photodetection. Data processing device 3 for numerically analyzing the signal sent from the instrument 3c to obtain an infrared absorption spectrum
d.

In the case of this embodiment, the optical fiber 4 is an AsS fiber which is a kind of chalcogenide glass fiber. The core of this AsS fiber is As4.
It has a composition of 0 mol% and S of 60 mol%, the clad is made of fluororesin (polytetrafluoroethylene), and the core / clad diameter is 220 / 240μ.
m. Further, the central portion of the optical fiber probe 6 is As
The clad is removed from the S fiber, and only the core is formed. The clad other than the central part and the clad of the optical fiber propagation part 5 are not removed. The total length of the optical fiber 4 is 10.1 m, the lengths of the optical fiber propagation parts 5 and 5 are 5 m, and the length of the optical fiber probe 6 is 0.1 m.

FIG. 3 shows the actual measurement results obtained by attaching distilled water, which is the measurement sample S, to the core of the optical fiber probe 6 by using such an infrared spectrum measuring apparatus.
Here, the horizontal axis of FIG. 3 is the wavelength (μm), and the vertical axis is the transmittance (%). As is clear from the figure, the obtained infrared spectrum has wavelengths around 3 μm and around 4.8 μm. 6μ
Absorption can be seen near m.

Next, the second aspect of the present invention will be described with reference to FIGS.
Examples will be described. Here, FIG. 4 is a schematic configuration diagram of the infrared spectrum measuring apparatus of the second embodiment, FIGS. 5 and 6 are graphs of actual measurement results of epoxy resin adhesives measured using the apparatus, and FIG. Before application, FIG. 6 shows measured values after application to the probe. In this embodiment, the FTIR as an infrared spectroscopic measurement unit including the light source unit 12 and the analysis unit 13 is incorporated.
A (Fourier transform infrared spectrophotometer) 11 and an optical fiber 4 for connecting the light source unit 12 and the analyzing unit 13 are provided. The optical fiber 4 includes optical fiber propagating units 5 and 5 at both ends and a central portion. It is composed of an optical fiber probe 6, and the optical fiber propagating portions 5 and 5 and the optical fiber probe 6 are coupled by respective connectors 7 so that their optical axes coincide with each other. Since the configuration of the optical fiber 4 and the configuration of the connector 7 are the same as those of the first embodiment, the description thereof will be omitted below.

The light source section 12 is a light emitting section 12 such as an infrared lamp which emits infrared rays containing a wavelength component of 1.5 to 25 μm.
a and the light emitted from the light emitting unit 12a are separated by a beam splitter or the like, and reflected by a movable mirror and a fixed mirror to interfere with two lights having an optical path difference δ (measurement light and reference light), and to generate interference light. An interferometer 12b to be created and a coupler 12c for injecting this interference light into the optical fiber propagating section 5 are provided, and the analyzing section 13 detects the incident light and a coupler 13a for connecting to the optical fiber propagating section 5. Equipped with a photodetector 13b,
The light detected by the photodetector 13b is observed as a function of the optical path difference δ and Fourier-transformed by the data processing device to obtain the spectrum of the measurement sample S.

Here, the optical fiber 4 of this embodiment is a GeAsSe fiber which is a kind of chalcogenide glass fiber. The core of this GeAsSe fiber is Ge18 mol%, As19 mol%, Se58 mol%,
Te has a composition of 5 mol%, and the clad has a composition of Ge 16 mol%, As 19 mol%, and Se 65 mol%.
The core / clad diameter is 300/330 μm. Further, since the cladding of the GeAsSe fiber is also glass, the outer periphery of the cladding is covered and protected with a urethane acrylate resin. Therefore, the optical fiber probe 6
The central part of the is composed of only the core with the cladding glass and protective coating removed from the fiber.

By the way, the clad glass at the center of the optical fiber probe 6 is removed by immersing it in a 1N NaOH solution for 1 hour. Further, the total length of the optical fiber 4 in this embodiment is 4.1 m, the lengths of the optical fiber propagation parts 5 and 5 are 2 m, and the optical fiber probe 6 is 6 m.
Has a length of 0.1 m, and the length of only the core is 2 cm.

The measurement results of the epoxy resin adhesive measured using the infrared spectrum measuring apparatus of this example are shown in FIGS. 5 and 6, and are shown in FIG. 5 before applying the adhesive and after the applying. As is clear from FIG. 6, 1600 cm ⁻¹ to 10
Absorption can be seen at 00 cm ^-1 . The horizontal axis of these graphs is the wave number (cm ⁻¹ ) and the vertical axis is the optical density.

As described above, even when the optical fiber propagating section 5 and the optical fiber probe 6 are not a single continuous fiber but the connector 7 is interposed, the measurement can be performed without any problem.

[0032]

As described above, the infrared spectrum measuring apparatus of the present invention is composed of the optical fiber probe capable of separating and splicing the optical fiber and the optical fiber propagating portion. Therefore, even if the optical fiber probe is damaged, it is expensive. There is no problem such as wasteful discarding of a different optical fiber propagation unit. Further, the optical fiber probe can be easily removed and attached, and the work can be easily performed even when the sample applied to the probe is hardened and is difficult to peel off.

Further, by removing the clad at the center of the optical fiber probe and exposing the core, the strength of the core is reduced, and work is performed in order to prevent damage to the same part when handling long optical fibers as a unit. Is very difficult to perform, but it is convenient in the present invention because it can be easily removed.

Further, if a chalcogenide glass fiber is used as the optical fiber used in the infrared spectrum device, the infrared light can be well propagated in the infrared region.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of an infrared spectrum device of the present invention.

[Figure 2] Enlarged view of the connector

FIG. 3 is a graph showing an actual measurement result of measuring distilled water with the apparatus of the first embodiment, in which the horizontal axis represents wavelength (μm) and the vertical axis represents transmittance (%).

FIG. 4 is a schematic configuration diagram of a second embodiment of the infrared spectrum device of the present invention.

FIG. 5 is a graph showing the actual measurement results of measuring the epoxy resin adhesive with the device of the second embodiment (the horizontal axis is the wave number (cm ⁻¹ ),
The vertical axis is the optical density, which is the state before applying the epoxy resin adhesive.

FIG. 6 is a graph showing the actual measurement results obtained by measuring an epoxy resin adhesive with the device of the second embodiment (the horizontal axis is the wave number (cm ⁻¹ ),
(Vertical axis is optical density), the state after applying epoxy resin adhesive

FIG. 7 is an explanatory diagram of the principle of the ATR method.

FIG. 8 is an explanatory diagram showing an example in which the ATR method is applied to an optical fiber.

[Explanation of symbols]

1 ... Infrared spectroscopic measurement unit, 2 ... Light source, 2a ... Infrared generation unit,
2b ... Coupler, 2c ... Optical system for making the light emitted from the emission section incident on the optical fiber propagation section as measurement light, 3 ... Spectroscope, 3a ... Coupler, 3b ... Grading, 3c ... Photodetector, 3d ... Data processing device 4 ... Optical fiber, 5 ... Optical fiber propagation part, 6 ... Optical fiber probe, 7 ... Connector, 8 ... Ferrule, 8a ... Outer taper, 8b ... Male screw, 9 ... Tapered guide tube, 9a ... Inner taper, 9b
... engaging projections, 10 ... fixing members, 10a ... engaging flanges,
10b ... female screw, 11 ... FTIR, 12 ... light source part, 12
b ... interferometer, 12c ... coupler, 13 ... analysis unit, 13a ...
Coupler, 13b ... Photodetector.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location // G01B 9/02 G02B 6/00 B (72) Inventor Toshiharu Yamashita 2 Nakaochiai, Shinjuku-ku, Tokyo 7th-5th Hoya Co., Ltd.

Claims (7)

[Claims] 1. An infrared spectrum measuring device comprising an infrared spectroscopic measuring section and an optical fiber in which a part of the optical fiber propagating section is used as an optical fiber probe, wherein the optical fiber probe and the optical fiber propagating section are separated and joined. Infrared spectrum measuring device characterized by making it possible. 2. The infrared spectrum measuring device according to claim 1, wherein the infrared spectroscopy measuring section includes a light source, a grating, a photodetector, and a coupler connected to an optical fiber. Infrared spectrum measuring device. 3. The infrared spectrum measuring apparatus according to claim 1, wherein the infrared spectroscopic measurement section includes a light source, an interferometer that measures a difference between the measurement light and the reference light, a photodetection section, and an optical detector. An infrared spectrum measuring apparatus, which is a Fourier transform infrared spectrophotometer comprising a coupler connected to a fiber. 4. The infrared spectrum measuring apparatus according to claim 1, wherein the means for separating and joining the optical fiber probe and the optical fiber propagating portion holds the tip of the optical fiber and has a male outer surface. A ferrule having a screw and an outer peripheral taper, a tapered guide tube into which the tip of the ferrule can be inserted, and an inner peripheral taper on the inner surface and an engaging projection on the outer surface, and a part of the tapered guide tube. An infrared spectrum measuring apparatus, characterized in that the connector is a cylindrical fixing member having a female screw and an engaging flange on its inner surface. 5. The infrared spectrum measuring device according to claim 1, wherein the optical fiber is a chalcogenide glass fiber. 6. An optical fiber probe, characterized in that the clad at the central portion of the optical fiber is removed and both ends are detachably attached to the optical fiber propagation part by the connector according to claim 4. 7. A method for producing an optical fiber probe, characterized in that the cladding glass in the central portion of the optical fiber is immersed in an alkaline solution and removed to form an optical fiber probe.