JPS6076646A - Liquid refractive-index sensor head - Google Patents

Abstract

PURPOSE:To obtain a refractive-index measuring method, whose explosion-proof property is excellent, by branching a main optical waveguide, which receives input light, forming two optical waveguides having bent parts with large and small curvatures, and detecting the output light beams. CONSTITUTION:A optical waveguide 3 is constituted by a main optical waveguide 4, which receives input light (a) and two branched optical waveguides 5 and 6. The branched optical waveguides 5 and 6 include bent parts 5a and 6a having different curvatures. The light from an input optical fiber 7 is outputted as output light beams (b) and (c) through output optical fibers 8 and 9. In measuring the refractive index of a liquid by using such a sensor head 1, the bent parts 5a and 6a of the head 1 are immersed in the liquid 10 to be measured, and the difference in intensities of the output light beams (b) and (c) is measured. Thus the refractive index of the liquid to be measured can be measured.

Description

Detailed Description of the Invention (a) Industrial Application Field This invention relates to a liquid refractive index sensor head for measuring the refractive index of a liquid to be measured, such as M oil in an oil refining plant, etc. This invention relates to a refractive index sensor head.

Naka) Conventional technology Conventionally, the method of measuring the refractive index of a liquid is

Monochromatic light is incident on the sample along the surface of the prism, and the resulting light beam corresponds to the refractive index of the fluid.

The light passes through a lens and a moving slit and is irradiated onto a photomultiplier tube.

The generated current rotates the balancing motor,
There is one that transmits this movement to a slit in front of a photomultiplier tube and moves the pointer at the same time. However, since this method includes an electric circuit in the measurement system, there are problems with explosion protection and remote sensing.

In oil refining plan 1~, it is necessary to measure the F (fraction index) of refined oil as one of the quality control of refined oil.

Due to the nature of the product, special attention must be paid to its explosion-proof properties during measurements, and remote sensing from the control room is also required.

(c) Purpose The purpose of this invention is to achieve the above-mentioned results and to provide excellent explosion-proof properties.

It is an object of the present invention to provide a liquid refractive index sensor head capable of performing refractive index measurement capable of remote sensing.

(b) Structure - In order to achieve the second object, the present invention provides that when an optical waveguide includes a circuit portion, the refractive index of the outer peripheral portion becomes large;
This method utilizes the fact that the degree of curvature is related to the curvature of the circuit section. The liquid refractive index sensor head of the present invention has a substrate, a main optical waveguide formed on the substrate and receiving human-powered light, and a relatively large circuit section branched from the main optical waveguide and having a curvature of 1. a first branch optical waveguide branched from the main optical waveguide;

a second branched optical waveguide having a circuit section with a curvature of 1", and calculates the refractive index of the liquid to be measured using the output light of the first and second branched optical waveguides. That's what I do.

0 → Example Hereinafter, this invention will be explained in more detail with reference to Examples.

FIG. 1 is a perspective view of a liquid refractive index sensor head showing an embodiment of the present invention, and FIG. 2 is a sectional view of the liquid refractive index sensor head shown in FIG. 1 taken along line I-1.

In FIGS. 1 and 2, a liquid refractive index sensor head 1
A leading waveguide 6 with a high refractive index formed by forceful ion exchange or the like is formed on a substrate 2 of a low-refractive heavy phase, such as galanus, which does not absorb light, thereby forming lY+:.

The optical waveguide 6 includes a main optical waveguide 4 that receives one input light a, and two branch optical waveguides 5 and 6 branched from the main optical waveguide 4. These branched optical waveguides 5 and 6 include circuit portions 5a and 6a having different curvatures, and the circuit portion 5a of the one-branched optical waveguide 5 is set to have a larger curvature.

An input optical fiber 7 is coupled to the main optical waveguide 4, so that input light a is input from an external light source (see FIG. 2). This input light a is guided to branched optical waveguides 5 and 6, and outputted as output lights A and C through output optical fibers 8 and 9 connected to the tip of this branched optical waveguide 5°. It has become.

When measuring the refractive index of oil or the like using the liquid refractive index sensor head 1 configured as described above.

As shown in FIG. 6, at least the circuit portions 5a and 6a of the branched optical waveguides 5 and 6 of the liquid refractive index sensor head 1 are immersed in the liquid 10 to be measured. Therefore, the liquid to be measured 10 is filled in the vicinity of the nine curved portions 5a and 6a.

Generally, in a straight waveguide, the center of the waveguide is O.

Fig. 4 (1') shows the refractive index distribution in the width direction X, 1 (,).
As shown in F), the refractive index is no up to the waveguide end T, and the refractive index outside thereof is ano (rr<1), which is even smaller than 110. In line with this, the refractive index I+' of the outer part of the four-curved waveguide
(X) is larger than that of a straight waveguide, and when converted to a straight waveguide, it becomes n(X)(1+X/R) (where R is the radius of curvature). Therefore, the difference between the refractive index of the outer portion of the curved waveguide and the refractive index within the waveguide is smaller than that of the straight waveguide, as shown in FIG. 4(b). As the refractive index difference between the inside and outside of the waveguide becomes smaller, the optical confinement function of the waveguide decreases accordingly. Furthermore, even in optical waveguides having circuit portions, the larger the curvature, the more pronounced this becomes. That is, for optical waveguides with different curvatures.

The number of propagating modes will differ, resulting in a difference in output light intensity.

From the above, in the liquid refractive index sensor head 1 of the above embodiment, the intensity of the output lights S and C led out to the output optical fibers 8 and 9 via the single-branch optical waveguides 5 and 6 is also determined at the 9-curve section 5a.
Since the curvatures of and 6a are different, they are different.

Furthermore, the refractive index of the liquid to be measured, such as oil, is different.

Example The relationship between the refractive index 11 of the liquid in which the liquid refractive index sensor head 1 is immersed and the amount of output light (c) is not shown in FIG. In other words, when the refractive index n of the immersion liquid becomes small, the difference in the refractive index between the inside of the nine-curved portions 5a and 6a becomes small, so the optical confinement function of the two-branch optical waveguides 5 and 6 decreases, and the output light beams S and C become small. becomes.

Also, as is clear from FIG. 5, the ratio of output light to C varies depending on the refractive index of the immersion liquid.

Therefore, by calculating the light amount ratio of the output light output from the output optical fiber 8 to the output light C output from the output optical fiber 9, can be detected.

In the first embodiment, one branched optical waveguide includes one enclosure, but each branched optical waveguide may of course include a plurality of enclosures.

The liquid refractive index sensor head of the two-layer embodiment is shown in FIG. 1. Since the output light S, c becomes O due to the different refractive index of the body, by monitoring this output light S, c, it can also be used to determine whether there is a person within a certain range of the refractive index of the liquid. .

(f) Effect The refractive index sensor head of this invention is formed of an optical waveguide,
Furthermore, since the input and output light can be input or derived using optical fibers, electric circuits such as the signal processing section are placed in a remote location, and an explosion-proof enclosure is obtained. However, by using it in conjunction with optical fiber, it becomes an ideal sensor for remote sensing. Since it handles distorted optical signals, it also has the advantage of not being affected by electromagnetic induction noise. Second, if we calculate the ratio of the output lights of the two branched optical waveguides, we get
Unaffected by light source output fluctuations, etc.

Highly accurate refractive index detection can be performed.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an optical waveguide type liquid refractive index sensor head showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the liquid refractive index sensor head shown in FIG. 1 taken along line I-1. , ;r
Figure 55 shows the state of immersion in the liquid to be measured when measuring using the liquid refractive index sensor head, Figure 4 shows the refractive index distribution inside and outside the optical waveguide, and Figure 4 @) shows the state of immersion in the liquid to be measured when measuring using the same liquid refractive index sensor head. A diagram showing the refractive index distribution, FIG. 4(b) is a diagram showing the refractive index distribution of the curved waveguide, and FIG. 5 is the liquid refractive index and output when the liquid refractive index sensor head of the above embodiment is immersed in the liquid. It is a figure showing the relationship of light. 1: Liquid refractive index sensor head, 2: Substrate. 4: Main optical waveguide, 5 and 6: Branch optical waveguide. 5a and 6a: enclosure section, 10: liquid to be measured. Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] (1) A liquid refractive index sensor head that is immersed in a liquid to be measured and for detecting the refractive index of the liquid to be measured. a main optical waveguide formed on the substrate and receiving input light; a first branch optical waveguide branched from the main optical waveguide and having a 4-dimensionally large circuit portion with a curvature of 9; Branched from the main leading wavepath. and a second branching optical waveguide having a circuit portion with a relatively small curvature, the output J light of the first and second branching optical waveguides is provided with a Liquid refractive index sensor head that calculates the index.