JPH0652239B2 - Fluid refractometer and fluid density meter using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fluid refractometer for liquids and gases and a fluid densitometer using the same, and a sensor fluid is directly immersed in the sample fluid to obtain a sample fluid. The refractive index and density of the sample fluid can be directly measured online at all times without performing sampling.

[Prior Art and its Problems] Conventionally, as an apparatus for measuring the refractive index of a fluid, for example, a liquid, in addition to the Abbe method for measuring the refraction angle of light by a prism and the minimum deviation angle method, the focal length changed depending on the refractive index of the sample. There are many known refractometers based on the law of refraction of light, such as the Duc de Chorne method for measuring.

However, in any of the liquid refractometers described above, the sensor unit for detecting the refractive index of the sample is directly connected to another device, and it is difficult to separate only the sensor unit. Therefore, since the sample liquid has to be sampled each time at the time of measurement, it has been impossible to constantly measure the refractive index of the liquid online.

Further, when the density is directly measured from the sample liquid, it is more difficult to sample, and even if the fact that the density of the liquid is given by the refractive index is used, the refractive index of the liquid is always online as described above. Since it is impossible to measure, constant online measurement of density was also impossible.

The present invention has been made to solve the above problems,
An object of the present invention is to provide a fluid refractometer and a fluid densitometer using the same, in which only the sensor probe is directly immersed in the sample fluid to constantly measure the refractive index of the fluid online.

[Means for Solving the Problems] According to the present invention, a focus reference plate is provided with a gap for guiding a fluid at the tip of a sensor probe, and measurement light is guided inside the sensor probe to illuminate the focus reference plate. The light guide and the image fiber that receives and guides the measurement light reflected from the focus reference plate are accommodated, and the measurement light guided by the image fiber is received to adjust the focus and move by the focus adjustment. A solution means is to provide a detection unit that detects the moving distance of the focus reference plate and a calculation unit that calculates the refractive index of the fluid based on the moving distance.

Further, the fluid densitometer of the present invention is a light guide for arranging a focus reference plate with a gap for introducing a fluid at the tip of the sensor probe, and guiding the measurement light in the sensor probe to illuminate the focus reference plate. And an image fiber that receives and guides the measurement light reflected from the focus reference plate, and receives the measurement light guided by the image fiber to adjust the focus, and the focus reference plate moved by the focus adjustment. The means for solving the problem is to provide a detection unit for detecting the moving distance and the calculating unit for calculating the refractive index of the fluid based on the moving distance and calculating the density of the sample fluid from the refractive index.

[Operation] A light guide for guiding the measurement light in the sensor probe,
Since the image fiber that receives and guides the reflected light from the focus reference plate is housed in parallel, only the sensor probe can be directly immersed in the sample fluid without sampling the fluid during measurement. Therefore, the refractive index of the fluid can always be measured online.

Furthermore, since the calculation unit can calculate the density from the refractive index of the fluid, the density of the fluid can always be measured online.

[Examples] Hereinafter, the present invention will be described in detail.

FIG. 1 shows an embodiment in which the present invention is used to measure the refractive index of a liquid. This liquid refractometer obtains the refractive index of the sample liquid by utilizing the fact that the focal length between the focus reference plate and the sensor probe changes due to the presence of the sample liquid, and it is a transparent substance based on the law of refraction of light. The Duc de Sorne method of the refractive index measurement method is used.

This liquid refractometer includes a light guide 2 having a light source 1 attached to one end, a detection unit 3 and a calculation unit 4 at one end, and a sensor probe 6 containing an image fiber 5 having an objective lens 8 attached to the other end. The focus reference plate 7 is provided to face the tip of the sensor probe 6 and can move back and forth.

The sensor probe 6 is a bundle of one end of the light guide 2 that guides the measurement light from the light source 1 and one end of the image fiber 5 to which the objective lens 8 that collects the reflected image is attached. The light guide 2 and the image fiber 5 are housed in a tubular protection member made of stainless steel or the like in order to protect them from extremely low temperatures such as liquefied gas and external stress. A low-loss optical fiber is used for the light guide 2, and a large number of core / clad optical fibers suitable for image transmission are bundled and fused and integrated as the image fiber 5. Further, the light guide 2 and the image fiber 5 accommodated in the sensor probe 6 are guided through a protection tube 10 formed by extending a protection member of the sensor probe 6, and the light guide 2
The light source 1 is connected to the other end of the image fiber 5, and the detection unit 3 and the calculation unit 4 are connected to the other end of the image fiber 5.

A sodium lamp, a laser, an LED, or the like having good monochromaticity is preferably used for the light source 1, and when white light or the like is used, it is preferable to use it by separating it into monochromatic light with a monochromatic filter. Is from light source 1 to light guide 2
Is guided to the sensor probe 6 and illuminates the focus reference plate 7.

The focus reference plate 7 is a smooth plate, and characters, ruled lines, etc. are marked on the surface thereof so that the focal length with the sensor probe 6 can be easily measured, and a gap is formed so as to face the sensor probe 6. It is arranged and attached to the focus adjuster 9. The focus adjuster 9 finely moves the focus reference plate 7 in the longitudinal axis direction of the sensor probe 6 to arbitrarily change the gap between the focus reference plate 7 and the sensor probe 6.

Further, the focus adjuster 9 is connected to a controller 11 connected to the detection unit 3, and is controlled by the controller 11 so that the detection unit 3 focuses the image transmitted through the image fiber 2.

Further, in the detection unit 3 connected to the image fiber 5,
An image monitor, an image recognition system device, etc. are built-in, and the controller 11 is instructed so that the image of the focus reference plate 7 transmitted by the image fiber 5 is in focus, and the focus moved to adjust the focal length. It is configured to detect the moving distance of the reference plate 7. The moving distance of the focus reference plate 7 detected by the detecting unit 3 is input to the calculating unit 4 after being converted into an electric signal, and the refractive index of the sample liquid is calculated using the law of light refraction here. It is like this.

In order to measure the refractive index of a liquid such as a liquefied gas at an extremely low temperature using the liquid refractometer having such a configuration, first, the focal length between the focus reference plate 7 and the sensor probe 6 in the atmosphere is obtained, and then the sensor is measured. The probe 6 is immersed in the liquefied gas of the sample liquid. Next, the lamp is caused to emit light, the wavelength is selected by the monochromatic filter, and then the light guide 2 illuminates the focus reference plate 7. The image image of the focus reference plate 7 is collected by the objective lens 8 attached to the tip of the sensor probe 6 and transmitted to the detection unit 3 by the image fiber 5. Since the image of the focus reference plate 7 transmitted to the detection unit 3 is out of focus due to the presence of the sample liquid, the detection unit 3 gives an instruction to the controller 11 to bring the image into focus. Therefore, the focus reference plate 7 attached to the focus adjuster 9 moves to determine the focal length between the sensor probe 6 and the focus reference plate 7. After the focal length is detected by the detection unit 3, it is adjusted by the controller 11 connected to the focus adjuster 9, and the ratio with the previously measured focal length in the atmosphere is detected. The ratio of the focal lengths is converted into an electric signal in the detection unit 3 and then transmitted to the calculation unit 4, where it is calculated using the following formula (1) to obtain the refractive index n of the sample liquid.

n = X ₁ / X ₂ (1) where X ₁ is the focal length in the atmosphere (n = 1.0), and X ₂ is the focal length in the sample liquid.

In the liquid densitometer of the second invention, the refractive index n of the sample liquid measured by the liquid refractometer is used, and the Lorentz-Lorenz equation (2) is used in the calculation unit 4 described above.
The density ρ of the sample liquid can be calculated with r being the relative refractive index difference peculiar to the liquid.

ρ = (n ² −1) / r (n ² +2) (2) In the above examples, the case where the refractive index and the density of the liquid are measured has been described, but the measurement of the refractive index and the density of the gas is performed. Can be similarly applied.

[Effects of the Invention] As described above, in the fluid refractometer of the present invention, a focus reference plate is provided with a gap for guiding a fluid at the tip of the sensor probe, and the measurement light is guided inside the sensor probe. A light guide that illuminates the focus reference plate and an image fiber that receives and guides the measurement light reflected from the focus reference plate, and adjusts the focus by receiving the measurement light guided by the image fiber. Since the detection unit for detecting the moving distance of the focus reference plate moved by the focus adjustment and the calculating unit for calculating the refractive index of the fluid based on the moving distance are provided, only the sensor probe is directly in the sample fluid. It becomes possible to immerse in.

Therefore, without sampling the fluid during measurement,
Since the sensor probe can be directly immersed in the sample fluid, the refractive index measurement of a cryogenic liquid such as a liquefied gas that cannot be normally sampled can be measured online at any time.

Further, in the fluid densitometer of the present invention, the density of the sample fluid can be calculated by the calculation unit using the measured refractive index of the sample fluid, so that the density can be always measured online, and the liquefaction can be performed. It is useful for production of gas and quality control.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a liquid refractometer of the present invention and a liquid density meter using the same. 1 ... Light source, 2 ... Light guide, 3 ... Detection section, 4 ... Calculation section, 5 ... Image fiber, 6 ... Sensor probe, 7 ... Focus reference plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Sanada 1440 Rokuzaki, Sakura-shi, Chiba Fujikura Electric Wire Co., Ltd.Sakura Factory (72) Inventor Kazumi Oni 20 (72) Inventor, 4273 Fujisawa, Kanagawa Kenji Nakamura 1-15-10 Honkitakata, Ichikawa-shi, Chiba (56) References Japanese Patent Publication Sho 49-36432 (JP, B1)

Claims (2)

[Claims] 1. A light guide for guiding a measuring light and illuminating the focus reference plate in which a gap for guiding fluid is provided at the tip of the sensor probe, and the focus reference plate is provided in the sensor probe. It accommodates an image fiber that receives and guides the more reflected measurement light, and also receives the measurement light guided by the image fiber to adjust the focus and detects the moving distance of the focus reference plate that has moved by the focus adjustment. A fluid refractometer, which is provided with a detection unit for performing the calculation and a calculation unit for calculating the refractive index of the fluid based on the moving distance. 2. A light guide for arranging a focus guide plate with a gap for introducing a fluid at the tip of the sensor probe, and guiding the measuring light to illuminate the focus reference plate and the focus reference plate. It accommodates an image fiber that receives and guides the more reflected measurement light, and also receives the measurement light guided by the image fiber to adjust the focus and detects the moving distance of the focus reference plate that has moved by the focus adjustment. A fluid densitometer, comprising: a detecting unit for calculating the refractive index of the fluid based on the moving distance, and a calculating unit for calculating the density of the sample fluid from the refractive index.