JP2002139423A - Oil film detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of an oil film detector by eliminating the need of using an expensive polarization beam splitter when oil film is detected. SOLUTION: This oil film detector is provided with a polarizing film 16 which reflects two light beams from LEDs 1 and 2 at the same position on the surface 6 of water and only transmits the P-polarized light component of reflected light which is parallel to the surface 6, another polarizing film 17 which only transmits the S-polarized light component of reflected light which is perpendicular to the surface 6, and photodiodes 13 and 14 which work as measuring means to measure the reflected light rays from the surface 6 transmitted through the films 16 and 17. The detector is constituted to detect the presence/absence of an oil film on the surface 6 by means of a signal processing means 15 by utilizing the light quantity ratio between the reflected light rays. Consequently, the detector does not require any expensive polarization beam splitter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil film detecting device for detecting oil floating on the surface of water, and more particularly, to oil flowing out of a factory drainage facility or oil flowing into a water intake facility such as a water purification plant or a farm. The present invention relates to an oil film detection device that automatically detects an oil film.

[0002]

2. Description of the Related Art In industrial wastewater, discharging wastewater mixed with oil into public waters is a social problem from the viewpoint of water pollution, and it is necessary to meet wastewater standards.
There is a need for a method and apparatus for continuously monitoring whether oil remains in the treated wastewater. On the other hand, oil pollution in raw water accounts for the majority of water quality accidents at water treatment plants, leading to serious accidents that require the shutdown of water intakes and cleaning of water treatment plants. There is a need for a method and apparatus for constantly monitoring the flow of oil into these water intake facilities because of the risk of contamination or death. In addition, in order to prevent river pollution, a manager who manages the river is demanding the appearance of a device capable of detecting oil.

[0003] For example, as a conventional method for optically non-contact and continuous automatic detection of the inflow of oil into water intake at a water purification plant, for example, a reflectance measurement method and an ellipsometry are known. The former reflectance measurement method uses a laser beam as the light source, irradiates the light source on the water surface, measures the amount of reflected light reflected from the water surface with a photodetector, and increases the reflectance of the water surface due to the presence of an oil film. Is used to detect the oil film. In the latter method of polarization analysis, a laser is used as the light source, and the light source is placed on the water surface.The polarization state of the reflected light reflected from the water surface is measured by a polarization analysis optical system. Is used to detect an oil film.

FIG. 4 shows a conventional example of an oil film detecting device based on the ellipsometry. This uses a laser light source 21 for the light emitting section,
The light beam 5 from the laser light source 21 is applied obliquely to the water surface 6, which is a floating wave of the oil film 7. The polarization state of the reflected light 8 reflected from the water surface 6 is measured by the light receiving unit. In the light receiving unit, of the reflected light scattered in various directions due to the rising of the water surface, the reflected light reflected at a fixed angle is received by the pinhole 9, and the received light is reflected by the polarizing beam splitter 10 on the optical axis and the surface of the water. A polarized light component (hereinafter, also referred to as a P-polarized light component) 11 parallel to a plane including the line and a polarized light component (hereinafter, also referred to as an S-polarized light component) 12 perpendicular to the plane,
The separated P-polarized light component 11 and S-polarized light component 12 are photoelectrically converted by photodiodes 13 and 14, respectively, and each light amount is converted into an electric signal.

[0005] Each of the photoelectrically converted electric signals is input to the signal processing means 15, and the signal processing means 15 calculates a light quantity ratio (also referred to as a polarization ratio) of the P-polarized component 11 and the S-polarized component 12, and calculates this polarization. The presence or absence of an oil film is determined by comparing the ratio with a normal reference value with no oil film on the water surface. When an oil film exists on the water surface, the reflected light intensity changes due to the difference in the refractive index between oil and water.
When examining the reflected light of 1 and the reflected light of the S-polarized light component 12, the way of change is different. Therefore, these ratios (polarization ratio)
Then, the value changes depending on the presence of the oil film, so that the oil film can be detected. As an oil leak detector for factory drainage, there are a capacitance-type impedance measurement method and an impedance measurement method using a microwave, which are inexpensive but all are contact-type and have low sensitivity.

[0006]

According to the above-mentioned ellipsometric method, high-sensitivity oil detection can be performed in a non-contact manner. However, in order to analyze the polarization state of light, a polarization beam splitter which is an expensive optical component is used. There is a problem that the components are required, and the cost is increased. Therefore, the object of the present invention is to
An object of the present invention is to reduce the cost by eliminating the need for a polarizing beam splitter or the like.

[0007]

In order to solve such a problem, according to the first aspect of the present invention, first and second light projecting means for irradiating two light beams to the same position on a water surface where oil is floating. And among the reflected light from the water surface of the first and second light projecting means, only the P-polarized light component parallel to the plane including the normal line of the water surface set at the point where the reflected optical axis intersects the water surface and the incident optical axis. First pass
Filter means, and second filter means for passing only S-polarized light components perpendicular to the plane out of the reflected light from the water surface of the first and second light projecting means, and the first and second filter means First and second measuring means for measuring the amounts of the P-polarized light component and the S-polarized light component of each reflected light passing through the light source, and signal processing means for determining the presence or absence of an oil film on the water surface based on the light amount ratio of the two reflected lights Are provided.

According to the second aspect of the present invention, the first and second light projecting means for irradiating two light beams to the same position on the water surface where oil is floating, and the water surface of the light beam from the first light projecting means First filter means for passing only a P-polarized component parallel to a plane including the incident optical axis of the water surface of the light incident on the water surface, and water surface of the light beam from the second light projecting means incident on the water surface. A second filter means for passing only an S-polarized component perpendicular to a plane including the incident optical axis, and first and second means for measuring the amount of reflected light passing through the first and second filter means and reflected on the water surface. And a signal processing means for determining the presence or absence of an oil film on the water surface based on the light amount ratio of the two reflected lights.

According to the third aspect of the present invention, the first and second light projecting means for irradiating two light beams to the same position on the water surface where oil floats, and the water surface of the light beam from the first light projecting means First filter means for passing only a P-polarized component parallel to a plane including the incident optical axis of the water surface of the light incident on the water surface, and water surface of the light beam from the second light projecting means incident on the water surface. A second filter unit that passes only an S-polarized component perpendicular to a plane including the incident optical axis of the second filter unit, and a third filter unit that passes only a P-polarized component that passes through the first filter unit and is reflected on the water surface,
A fourth filter unit that passes only the S-polarized light component that passes through the second filter unit and is reflected on the water surface;
First and second measuring means for measuring the amount of P-polarized light component and S-polarized light component of each reflected light passing through the filter means and reflected on the water surface, and the presence or absence of an oil film on the water surface based on the light amount ratio of the two reflected lights And a signal processing means for determining

That is, according to the first aspect of the present invention, a first filter that reflects two light beams at the same position on the water surface and passes only a P-polarized component to the first reflected light, and a second filter that reflects the second reflected light On the other hand, a second filter that passes only the S-polarized component,
First and second measuring means for measuring the light amount of each reflected light passing through the second filter are provided, and the presence or absence of an oil film is detected based on the light amount ratio from the first and second measuring means. .
In other words, the polarizing beam splitter used conventionally is very expensive because, for example, a dielectric multilayer film is applied to the slope of the right-angle prism based on computer simulation, but the polarizing film used as a filter in the present invention is not so expensive. It is inexpensive for each stage only by extending a polymer having a long chain structure. Therefore, an inexpensive and simple oil film detecting device can be provided without using a polarizing beam splitter. In the invention of claim 1,
Although a filter made of a polarizing film or the like is provided for reflected light, a filter made of a polarizing film or the like may be provided for irradiation light as in the invention of claim 2. It may be provided for both reflected light and irradiation light as in the invention. In any case, continuous detection of the oil film can be performed at low cost without using a polarizing beam splitter or the like.

[0011]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention. 4 is different from the conventional example shown in FIG. 4 in that two light emitting diodes (LEDs) 1 and 2 are used as light sources, and of the reflected light from the water surface 6 with respect to the irradiation light emitted from the first LED 1, And parallel components (P
While the polarizing film 16 is disposed so as to pass only the polarized light component, only the component (S-polarized light component) perpendicular to the water surface 6 out of the reflected light from the water surface 6 with respect to the irradiation light emitted from the second LED 2 Is that the polarizing film 17 is disposed so as to allow the light to pass therethrough, and the polarizing beam splitter is not required. At this time, the condition is that the irradiation lights of the two LEDs 1 and 2 are incident on the same position on the water surface 6. Also, each LED is
It is assumed that the light output is such that the ratio of the amount of light reflected on the water surface without the oil film becomes a predetermined value.

In such a configuration, when there is no wave on the water surface 6, the two reflected lights 8 reflected at the same position on the water surface 6
After restricting the optical path to a certain angle by the pinhole 9 and passing through the polarizing films 16 and 17, respectively, the amount of reflected light is measured by the photodiodes 13 and 14, and the P-polarized component and S By determining the reflected light amount ratio of the polarized light component, the presence or absence of an oil film can be detected. Thus, the oil film can be detected at low cost, simply, and continuously without using a polarizing beam splitter.

FIG. 2 shows a second embodiment of the present invention. This is different from that shown in FIG. 1 in that a polarizing film is provided not for reflected light 8 but for irradiation light (light beam 5) as shown by reference numerals 3 and 4. The points are the same as those in FIG. 1 and the effects are the same, so that the description will be omitted.

FIG. 3 shows a third embodiment of the present invention. As is clear from the figure, this is a composite of the one shown in FIG. 1 and the one shown in FIG. That is, a polarizing film is provided for irradiation light (light beam 5) as shown by reference numerals 3 and 4, and
As shown by 7, it is characterized in that it is provided for the reflected light 8, and the other points are the same as those in FIG. 1 or FIG.

[0015]

According to the present invention, in an apparatus for automatically and continuously detecting oil flowing out of a factory drainage facility or the like, or oil flowing into a facility such as a water purification plant or an aquaculture plant, a conventionally required expensive device is used. Since there is no need to use a polarizing beam splitter,
This provides the advantage that an inexpensive and simple device can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a conventional example.

[Explanation of symbols]

1, 2,... LED (light emitting diode), 3, 4, 16, 1
7: polarizing film, 5: light beam (irradiation light), 6: water surface, 7: oil film, 8: reflected light, 9: pinhole, ..., 1
1,18 ... P polarization component, 12,19 ... S polarization component, 1
3, 14 ... photodiodes, 15 ... signal processing means.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tokio Oto 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Hiroshi Tada 1 Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture No. 1 Fuji Electric Co., Ltd. (72) Inventor Hideo Kanai 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture F-term (reference) 2G059 AA05 BB04 EE02 EE05 GG02 GG03 GG04 JJ19 KK01 KK03 MM05 5F089 BA05 BB03 BC02 BC22 CA21 GA10

Claims (3)

[Claims] 1. A first and a second light projecting means for irradiating two light beams to the same position on a surface of a water on which oil floats,
A first filter means for passing only a P-polarized component parallel to a plane including a normal line of the water surface and a plane including the incident optical axis at a point where the reflection optical axis intersects with the water surface in the reflected light from the water surface of the second light projecting means; And second filter means for passing only the S-polarized light component perpendicular to the plane out of the reflected light from the water surface of the first and second light projecting means, and passing through the first and second filter means. First and second measuring means for measuring the amounts of P-polarized component and S-polarized component of each reflected light, and signal processing means for determining the presence or absence of an oil film on the water surface based on the ratio of the amounts of the two reflected lights are provided. Oil film detector. 2. First and second light projecting means for irradiating two light beams to the same position on a water surface where oil floats, and light incident on the water surface of a light beam from the first light projecting means. The first of which passes only the P-polarized light component parallel to the plane containing the incident optical axis of the water surface
A filter means, and a second filter means for passing only an S-polarized component perpendicular to a plane including an incident optical axis of the water surface out of light incident on the water surface of the light beam from the second light projecting means; 1. First and second measuring means for measuring the amount of reflected light passing through the second filter means and reflected on the water surface, and signal processing for judging the presence or absence of an oil film on the water surface based on the ratio of the amounts of the two reflected lights. And an oil film detecting device. 3. A first and a second light projecting means for irradiating two light beams to the same position on a water surface on which oil floats, and a light beam from the first light projecting means incident on the water surface. The first of which passes only the P-polarized light component parallel to the plane containing the incident optical axis of the water surface
A filter means, and a second filter means for passing only an S-polarized component perpendicular to a plane including an incident optical axis of the water surface out of light incident on the water surface of the light beam from the second light projecting means; A third filter means that passes only the P-polarized light component passing through the first filter means and reflected on the water surface, and a fourth filter means that passes only the S-polarized light component passed through the second filter means and reflected on the water surface.
Filter means, first and second measuring means for measuring the amount of P-polarized light component and S-polarized light component of each reflected light passing through the third and fourth filter means and reflected on the water surface, and two reflection means. An oil film detection device comprising: signal processing means for determining the presence or absence of an oil film on a water surface based on a light amount ratio of light.