JPH01197632A - Liquid refractometer and liquid concentration meter using same - Google Patents

Abstract

PURPOSE:To measure the refractive index, etc., of liquid on an on-line basis at all times by dipping only a probe in the liquid to be measured directly by connecting the probe to respective parts by light guides or image guides consisting of optical fibers. CONSTITUTION:The probe 4 is dipped in the liquid 3 to be measured and the groove of a liquid prism part 9 is filled with the liquid 3 to form a liquid prism 8. Then measurement light PA with specific wavelength is guided to the probe 4 by a light guide 6. The guided measurement light PA is made by an optical transmission part 10 into linear parallel luminous flux, which is entered into the liquid prism 8 and photodetected by the start end part B of an image guide 7. Namely, a bright line L is image-formed on the photodetection surface (f) of the start end part B at a position corresponding to the deviation angle of the liquid prism 8 and the position of this bright line L varies with the refractive index of the liquid to be measured. Then position information on the bright line L is inputted to a processing part 5 by the image guide 7. The processing part 5 inputs the position information on the bright line L and performs programmed arithmetic processing to find the refractive index of the object liquid 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fluid refractometer for liquids, gases, etc., and a fluid density meter using the same. This allows the refractive index and density of the measurement fluid to be measured online at all times.

[Prior art and its problems] Conventionally, devices for measuring the refractive index of fluids, such as liquids, include the Atsube method, which measures the angle of refraction of light by a prism, the minimum deviation method, and other methods that depend on the refractive index of the liquid to be measured. Refractometers based on the law of refraction of light, such as the Duc de Charne method, which measures the focal length that changes due to the change in the focal length due to the change in the focal length, are widely known. Further, since a certain relational expression holds between the refractive index and the density of the liquid to be measured, as will be described later, a liquid density meter using the above liquid refractometer is also known. However, in both the liquid refractometer and the liquid density meter using the liquid refractometer, the probe that detects the refractive index and density of the liquid to be measured is directly connected to other components such as a light source and a processing section, so that only the probe can be used. Difficult to separate.

Therefore, it is necessary to sample the liquid to be measured each time the measurement is made, so it has been impossible to constantly measure the refractive index and density of the liquid to be measured online.

This invention was made to solve the above problems, and by connecting the probe, a light source, and a processing section with a light guide or an image guide made of optical fiber, only the probe can be directly immersed in the measurement fluid. The object of the present invention is to provide a fluid refractometer that can measure the refractive index and density of a fluid online at all times, and a fluid density meter using the fluid refractometer.

[Means for Solving the Problems] According to the present invention, a probe is provided with a fluid prism section that is filled with a fluid to be measured to form a fluid prism, and a transmitter that guides measurement light to the fluid prism section is provided. Contains a light section and a light receiving section that receives measurement light from the fluid prism section,
A light guide that guides measurement light to the light transmitting section is connected to the light source and the light transmitting section, an image guide that guides the measurement light from the light receiving section is connected to the light receiving section and the processing section, and the above processing By determining the refractive index of the measuring fluid based on the light receiving position information detected by the light receiving part in the part,
A light transmitting part that guides measurement light to the fluid prism part and a light receiving part that receives the measurement light from the fluid prism part are installed in the probe which is provided with a fluid prism part that is filled with a measuring fluid to form a fluid prism part. A light guide for guiding the measurement light from the light receiving section is connected to the light source and the light transmitting section, and an image guide for guiding the measurement light from the light receiving section is connected to the light receiving section and the processing section. The above problem is solved by determining the density of the measurement fluid in the processing section based on the light receiving position information detected by the light receiving section.

[Function] In the fluid refractometer of this invention and the fluid density meter using the same, the probe and each part are connected by a light guide or an image guide made of an optical fiber, so only the probe is immersed in the measuring fluid. can do.

Moreover, only the probe can be installed at a remote location.

Therefore, the refractive index and density of the fluid can be measured online at all times without sampling the fluid to be measured during measurement.

[Example ] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 show an embodiment in which the present invention is used to measure the refractive index of a liquid. In FIG. 1, reference numeral 1 indicates a liquid refractometer in this example. This liquid refractometer (■) includes a light source 2 that emits measurement light for refractive index measurement, a probe 4 that passes the measurement light into a measurement liquid 3 to detect the declination angle due to refraction, and a refractive index based on the declination angle. The probe 4 and the light source 2 are connected to each other by a light guide 6, and the probe 4 and the processing part 5 are connected to each other by an image guide 7.

The light source 2 is composed of a lamp and an appropriate monochromatic interference filter. For example, a combination of a sodium lamp and an interference filter that selectively transmits only sodium D rays can be used.

Suitable lamps and filters can be selected depending on the measurement wavelength range. Further, as shown in FIG. 2, the probe 4 includes a liquid prism part 9 that is filled with the liquid to be measured 3 to form a liquid prism 8 during measurement, and a light transmission part that makes the measuring light PA incident on the liquid prism 8. 10 and the measurement light PB refracted by the liquid prism 8.
The light receiving section 11 receives the light at a position on the light receiving surface f according to the polarization angle (angle formed by the incident light PA and the emitted light PB) δ. The liquid prism section 9 is constructed by forming two transparent optically parallel flat plates (for example, quartz glass plates) into a triangular groove on both sides. , forming a liquid prism 8 made of the measuring liquid 3. Further, the light transmitting section IO is composed of optical members including a collimator lens I2, a slit 13, and a mirror I4. A light guide 6 is provided on the object side focal plane of the collimator lens 12.
The terminal end A of the collimator lens I is attached, and the collimator lens I
The measurement light PA incident on the light beam 2 is converted into a parallel light beam and then emitted. A slit 3 is disposed on the image space side of the collimator lens 12 to convert the measurement light PA emitted from the collimator lens 12 into a linear parallel light beam. The mounting position of the mirror 14 is adjusted so that the measurement light PA is incident on the liquid prism 8 at a predetermined angle. Further, the starting end of the light guide 6 is attached to the light source 2. Here, as the light guide 6, a fiber bundle formed by bundling a plurality of fibers is used. In addition, "2 light receiving section 1! is objective lens 1
It is composed of an optical system consisting of 5 parts. This objective lens 15 is the measurement light PI3 refracted by the liquid prism 8.
is placed on the optical path. The starting end B of the image guide 7 is attached to the light receiving section 11 so that the light receiving surface f of the image guide 7 overlaps the image forming surface of the objective lens 15. On the other hand, the terminal end of the image guide 7 is attached to the processing section 5. Here, as the image guide 7, an image fiber capable of faithfully transmitting two-dimensional images is used. The processing unit 5 is configured to obtain the refractive index based on the declination information of the measurement light PB transmitted by the image guide 7, for example, by performing program calculation processing or by measuring with a scale. .

In the liquid refractometer 1 of this example, the probe 4 is placed in a protective container 1 that is liquid-tight to prevent the measurement liquid 3 from flowing in.
It is stored in 6. Suitable materials for use in the protective container 16 include those that do not dissolve into the liquid to be measured 3, such as metal materials such as stainless steel, inorganic materials such as glass, and hard plastic materials. Further, the portions of the light guide 6 and the image guide 7 that are immersed in the measurement liquid 3 are also covered with a flexible protective tube 17.

To measure the refractive index of the liquid to be measured 3 using the liquid refractometer 1 with the above configuration, first, as shown in FIG. The groove is filled with measuring liquid 3 so that a liquid prism 8 is formed. Next, the measurement light PA of a predetermined wavelength is guided to the probe 4 by the light guide 6. The measurement light PA guided in this way is made into a linear parallel light beam in the light transmitting section 10 and is incident on the liquid prism 8, where it is refracted and then reflected in the image guide 7 attached to the light receiving section 11. The light is received at the starting end B. That is, as shown in FIG. 3, a bright line is imaged on the light-receiving surface f of this starting end B at a position corresponding to the deflection angle δ by the liquid prism 8, and the position i of this bright line is the same as that of the liquid to be measured. It depends on the refractive index of This bright line position information is guided to the processing section 5 by the image guide 7. In the processing section 5, the positional information of the guided bright line is input and a program calculation process based on optical theory is performed to obtain the refractive index of the measurement liquid 3 at the measurement wavelength. Alternatively, as another calculation method, the correlation between the light receiving position and the refractive index may be determined in advance using a liquid with a known refractive index, and the refractive index may be calculated from this.

Next, an example in which the present invention is used to measure the density of a liquid will be described. The liquid density meter in this example has the same configuration as the liquid refractometer shown in Figures 1 and 2, except for the different processing section, so the position of the emission line is the same as that shown in Figure 3. The process until information is guided from the image guide to the processing section is similar to the liquid refractometer in the above example. In the processing section of this example, the refractive index of the liquid to be measured is first determined using an algorithm using the Lorentz-Lorentz equation shown below, and the density can be easily determined from the determined refractive index. ing.

ρ-(n' 1)/r (n''+2) (where,
ρ represents the density of the liquid to be measured, n represents the refractive index of the liquid to be measured, and r represents the specific refraction of the liquid to be measured. ) According to the liquid refractometer 1 having the above configuration and the liquid density meter using the same, the probe 4 can be separated from the light source 2 and the processing section 5, and only the probe 4 can be immersed in the measurement liquid 3. Therefore, the refractive index and density of a separated liquid can be measured online at all times without sampling the measurement liquid 3 during measurement.

In particular, it is suitable for measuring the refractive index and density of cryogenic liquids such as liquefied gases, which cannot normally be sampled, and flowing liquids.

Furthermore, by detecting the temporal position change (ΔX) of the bright line, it is possible to know the temporal change in the refractive index and density. Furthermore, by moving the probe within the liquid to be measured, the refractive index distribution and density distribution within the liquid to be measured can be determined. This is useful for manufacturing and quality control of liquids (such as liquefied natural gas) stored in huge tanks.

In the above example, an image fiber is used as the image guide 7, but the present invention is not limited to this, and a fiber array capable of transmitting a -dimensional image may be used. In this case, a bright spot is transmitted instead of a bright line due to the probe light PB.

Furthermore, a CCD line sensor may be arranged on the light receiving surface f. In this case, an electric cable will be used instead of the image fiber.

In addition, in the above-mentioned example of the liquid density meter of the present invention,
First, a case has been described in which the refractive index of the liquid to be measured is determined and the density is easily determined from the determined refractive index, but the configuration may be such that the density is directly determined from the positional information of the emission line.

Although the above example was an example of measuring the refractive index and density of a liquid, the 111 constant of the refractive index and density of a gas can be similarly determined.

[Effects of the Invention] As explained above, the fluid refractometer of the present invention and the fluid density meter using the same connect a light source and a probe with a light guide made of an optical fiber, and connect the probe and a processing section. Since the probe is connected by an image guide made of an optical fiber, only the probe can be immersed in the measurement fluid. Moreover, only the probe can be installed at a remote location. Therefore, the refractive index and density of the fluid can be measured online at all times without sampling the fluid to be measured during measurement.

In particular, it is suitable for measuring the refractive index and density of cryogenic liquids such as liquefied gases, which cannot normally be sampled, and flowing liquids.

Furthermore, since the refractive index distribution and density distribution in a liquid stored in a huge tank can be easily measured, it is useful, for example, in the production and quality control of liquefied natural gas and the like.

[Brief explanation of the drawing]

1 and 2 show an embodiment of a liquid refractometer according to the present invention. FIG. 1 is a schematic configuration diagram showing the overall configuration, and FIG. 2 is a main part of the detection section of this liquid refractometer. FIG. 3, which is an enlarged view of the main part showing the structure, is an explanatory diagram showing a pattern in which the positions of the bright lines on the light-receiving surface differ depending on the difference in the refractive index of the liquid to be measured. 1... Liquid refractometer 2... Light source 3... Measuring liquid 4... Probe 5... Processing section 6...・Light guide 7...Image guide 8...Liquid prism 9...Liquid prism section PA, FB...Measurement light 10...Transmission Light part +1... Light receiving part.

Claims (2)

[Claims] (1) A light transmitting part that guides the measurement light to the fluid prism part and a light receiving part that receives the measurement light from the fluid prism part, in a probe equipped with a fluid prism part that is filled with a fluid to be measured to form a fluid prism part. A light guide that guides the measurement light to the light transmission section is connected to the light source and the light transmission section, and an image guide that guides the measurement light from the light reception section is connected to the light reception section and the processing section. A fluid refractometer, characterized in that the refractive index of the fluid to be measured is determined based on the light receiving position information detected by the light receiving section in the processing section. (2) A light transmitting part that guides measurement light to the fluid prism part and a light receiving part that receives the measurement light from the fluid prism part, in a probe equipped with a fluid prism part that is filled with a fluid to be measured to form a fluid prism part. A light guide that guides the measurement light to the light transmission section is connected to the light source and the light transmission section, and an image guide that guides the measurement light from the light reception section is connected to the light reception section and the processing section. A fluid density meter, characterized in that the processing section is connected to a fluid density meter, and the processing section calculates the density of the fluid to be measured based on the light receiving position information detected by the light receiving section.