JPH0228541A - Optical concentration detector - Google Patents

Abstract

PURPOSE:To measure the contamination condition of a window of a container forming an optical path in real time with high sensitivity by irradiating the window with another light from the outside surface side thereof and detecting the quantity of the total reflected light thereof. CONSTITUTION:The light, for example, helium-neon laser light, from a 1st light emitting part 3 is made incident to the inside of the container through the window 2 and is received in a 1st light receiving part 4. A liquid concn. is measured in accordance with the quantity of said light if there is no contamination of the window 2. A prism 5 is brought into tight contact with the outside surface side of the window 2 and a 2nd light emitting part 6 and the 2nd light receiving part 7 are provided. The helium-neon laser light from the light emitting part 6 is made incident to the prism 5 in such a manner that the incident angle attains the total reflection angle or above and the reflected light thereof is received in the light receiving part 7. The voltage corresponding to the light signal is detected by a power meter, by which the degree of contamination of the window 2 is measured in real time with high sensitivity. The measured concn. value is, thereupon, corrected according to the detected value, by which the exact concn. is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a device for optically detecting the concentration of liquid, etc. in a container, and in particular has a function of detecting contamination on the inner surface of the window of the container. It is related to the device.

B1 Summary of the Invention The present invention provides a device for optically detecting the concentration of a liquid, etc. in a container, in which light is separately irradiated from the outer surface of a window of the container that forms an optical path;
By detecting the amount of totally reflected light, the contamination status of window surfaces can be measured in real time with high sensitivity.

C0 Prior Art Currently, the concentration inside a tank is measured by passing light through the liquid in the tank and detecting the amount of light received. However, the window surface through which the light passes becomes contaminated with contaminants in the liquid, resulting in a decrease in the amount of light received, resulting in measurement errors and often making accurate concentration measurements impossible. Therefore, it is necessary to monitor the contamination status of the window surface and correct the measured concentration value according to the degree of contamination, or to clean the window surface if the degree of contamination is high. For this reason, conventionally, the amount of received light has been detected by visually inspecting the window surface or by draining the liquid in the container.

D1 Problems to be Solved by the Invention However, in the conventional method, the measurement of the concentration of the liquid had to be interrupted, and it was not possible to monitor it in real time. Furthermore, visual inspection cannot accurately determine the degree of contamination, and the method of draining the liquid is time-consuming.

SUMMARY OF THE INVENTION An object of the present invention is to provide a convenient optical concentration detection device that is capable of detecting the degree of contamination on a window surface with high sensitivity in real time.

89 Means for Solving the Problems The present invention allows light from a first light-emitting section to enter the container, receives the light by the first light-receiving section, and detects the inside of the container based on the amount of received light. A device for detecting the concentration of a substance contained in the container includes a prism provided in close contact with the outer surface of a window forming a part of the optical path of the container, and a prism that irradiates the window with light for detecting window contamination through the prism. The light emitting device includes two light emitting sections and a second light receiving section that receives light from the second light emitting section reflected by the window.

20 Effect When the light from the second light emitting part is incident on the window so as to be totally reflected, the amount of the total reflected light is reduced by the contaminants on the inner surface of the window, so it is not based on the amount of received total reflected light. The contamination status of the inner surface of the window can be detected.

G. Embodiment FIG. 1 is a diagram showing an embodiment of the present invention, in which 1 is a container containing a liquid, 2 is a window, 3 is a first light emitting section, 31 is an optical fiber, and 4 is a light receiving section. . The configuration up to this point is the same as the conventional one, and the light from the first light emitting section 3, for example, helium-neon laser light, enters the container l through the window 2, passes through it, and enters the container l. The light is received by one light receiving unit 4. Therefore, if the window 2 is clean, the liquid concentration corresponds to the amount of light received by the first light receiving section 4, and the liquid concentration can be measured based on the amount of light received.

Here, in the embodiment of the present invention, a prism 5 is provided on the outer surface side of the window 2.
A second light emitting section 6 that irradiates light for contamination detection, such as helium-neon laser light, to both sides of the prism 5, and a second light receiving section that receives reflected light of the laser light from here. 7. 6. is an optical fiber.

In such an embodiment, the incident angle of the laser beam from the second light emitting unit 6 to the window 2 is a total reflection angle, for example, 61.7.
The reflected light is received by the second light receiving section 7, and the voltage corresponding to the optical signal is captured by a power meter (not shown).

Using this device, marker ink is applied to the inner surface of the window 2, and the degree of contamination (degree of contamination) is determined based on the amount of light received by the first light receiving section 4 that receives the light from the first light emitting section 3. During the measurement, the amount of light received by the second light receiving section 7 that received the reflected light from the second light emitting section 6 at that time was measured. Each light receiving section 4,
The amount of light received in No. 7 was captured as a voltage value using a power meter.

FIG. 2 shows data showing the results, and it can be clearly seen that there is a correlation between the degree of contamination and the output value (voltage) of the second light receiving section 7. The reason why the amount of reflected light decreases as the degree of contamination increases is that when contaminants adhere to the inner surface of window 2, the refractive index of the medium on the inner surface of window 2 increases, so the amount of light that passes through the window decreases. This is thought to be due to an increase in

On the other hand, by changing the concentration of the liquid without contaminating the window 2,
The relationship between the output value of the light receiving section 7 and the liquid concentration was investigated. The results are shown in FIG. However, the liquid concentration was measured using the first light emitting section 3 and the first light receiving section 4.

This result shows that the amount of light totally reflected by the window 2 is sensitive to contamination on the inner surface of the window 2, but is not affected by the liquid concentration.

H6 Effects of the Invention According to the present invention, the contamination status of the window used for light intensity detection is determined by measuring the amount of light totally reflected by the window, so the degree of contamination of the window surface can be detected in real time with high sensitivity. Therefore, it is possible to correct the measured concentration value according to the detected value, thereby making it possible to detect an accurate concentration, and also eliminating the need for troublesome work such as draining the liquid from the container.

Moreover, since the structure is simple and the amount of light is low, it can enjoy advantages such as no need for a power source on site, safety, and no guidance.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a data diagram showing the relationship between the output of the second light receiving section and the degree of contamination, and FIG. 3 is a diagram showing the relationship between the output of the second light receiving section and the liquid concentration. It is a data diagram showing a relationship. ■... Container, 2... Window, 3゜6... Light emitting section, 4゜7... Light receiving section, 5... Prism. Configuration diagram of the embodiment■...Container 2...Window 3.6...Light emitting section 4.7...Light receiving section 5...Prism

Claims (1)

[Claims] (1) A device that makes light from a first light emitting part enter the container, receives the light by a first light receiver, and detects the concentration of the contents in the container based on the amount of received light. A prism provided in close contact with the outer surface side of the window forming a part of the optical path of the container; a second light emitting unit that irradiates the window with light for detecting window contamination through the prism; and a second light receiving part that receives the light from the second light emitting part reflected by the window, and the light from the second light emitting part is incident on the window so as to be totally reflected, and the reflected light is An optical concentration detection device characterized by detecting contamination on the inner surface of a window based on the amount of light received.