JPH10281980A - Oil film detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain continuous automatic monitoring of a very small amount of oil content with high sensitivity and accuracy by irradiating light beams including both polarization elements of P, S to a water surface, and obtaining the light quantity ratio of the both polarization elements from its reflected light for comparison with a reference value. SOLUTION: From a laser light source 1 having circularly-polarized light characteristics, light beams 4 including a P polarization element (polarization element in the vibrating direction 2 of P polarization element) and S polarization element (polarization element in the vibrating direction 3 of S polarization element) equally are irradiated to a wavy water surface at an incident angle 7, which is floated with an oil film 5. A reflected light 10 is passed through a polarized beam splitter 12, and after separation into the P polarization element 13 and the S polarization element 14, respective light quantities are converted into electric signals by photodiodes 15, 16. After the electric signals are amplified respectively, the light quantity ratio of the both elements 13, 14 are computed and outputted by an arithmetic circuit 19. The signal is moving-averaged and is compared with a reference value at the time of normal condition which has no oil film 5 on the water surface, by a comparing circuit 24. If it exceeds a preset range, it is discriminated that the oil film is present, thereby outputting an alarm 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for detecting an oil film on a water surface. More specifically, the present invention relates to an oil film detecting device that automatically detects an oil component flowing into a water purification plant, a farm, or the like, or an oil component flowing out of a factory drainage facility or the like as an oil film on the water surface.

[0002]

2. Description of the Related Art In a water purification plant, oil contamination of raw water accounts for about half of water quality accidents, which is a serious accident that requires the suspension of water intake and cleaning of the water purification plant. Due to the risk of product contamination or death, there is a need for a method and apparatus for constantly monitoring the flow of oil into these water intakes. On the other hand, in factories, discharging wastewater mixed with oil into public waters is a social problem as water pollution, so it is necessary to meet wastewater standards, and whether oil remains in the treated wastewater. There is a need for a method and apparatus for continuously monitoring whether or not.

[0003] As a method of automatically detecting the inflow of oil into water at a water purification plant, for example, (1) a reflectance measurement method,
(2) There is an image monitoring method using a TV camera, and the like. Also,
Methods for detecting oil content in wastewater in factories include, for example, (3) hexane extraction / gravimetry, (4) extraction / infrared absorption measurement, (5) emulsification / turbidity measurement, (6) fluorescence measurement, etc. Is conventionally known.

[0004] The outline of each of these measurement methods will be briefly described below. (1) The reflectance measurement method uses a laser or an LED as a light source to irradiate a light beam on the water surface, and detects an oil film by utilizing the fact that the reflectance of reflected light increases due to the presence of an oil film. (2) In the image monitoring method using a TV camera, the water surface is illuminated by an illumination device, the water surface is photographed by a TV camera, and the obtained image is binarized. Here, the reflectance of the oil film is higher than that of water. In this method, a threshold value for binarization is set between the water surface and the reflectance of the oil film to detect the oil film.

(3) In the hexane extraction / gravimetric method, the oil content in a sample is extracted with n-hexane, then only n-hexane is volatilized at 80 ° C., and the mass of the remaining substance is measured to determine the amount of oil content. Is the way. (4) Extraction / infrared absorption measurement method is a method of extracting oil in an extraction solvent such as carbon tetrachloride and measuring the absorption spectrum near a wavelength of 3.4 μm peculiar to the oil with an infrared analyzer to determine the oil concentration. It is.

(5) The emulsification / turbidity measurement method is a method of emulsifying an oil component in a sample by ultrasonic waves or the like, and measuring the oil component concentration from a change in turbidity before and after the emulsification. (6) The fluorescence measurement method is a method of irradiating a sample water with ultraviolet light, measuring fluorescence having a specific wavelength longer than irradiation light generated from oil, and measuring the oil concentration.

[0007]

As described above, various oil detecting devices have been conventionally used. However, these devices generally have difficulty in continuous automatic measurement, difficulty in detecting a trace amount of oil, There are problems such as many malfunctions. The following describes these problems in more detail. Take, for example, the monitoring of the inflow of oil into the water intake facility of a water purification plant. Oil pollution of raw water is mainly caused by illegal dumping of oil into rivers or oil spills caused by accidents, so that it is not known when it will occur, so 24-hour continuous automatic monitoring is required.
Also, from the viewpoint of being used for drinking water, even a minute amount of oil contamination becomes a serious accident, and the ability to detect a very small amount of oil on the order of ppb to ppm is required. However, current equipment does not satisfy these requirements, so many water purification plants require a lot of labor such as 24-hour inspection of humans by smelling water and visual observation of water intake. Is still taken.

[0008] The problems of the above-described measuring methods will be briefly described below. (1) The reflectance measurement method and (2) the image monitoring method using a TV camera are methods capable of continuous automatic monitoring, and can effectively detect an oil film on a still water surface. When a floating substance other than oil passes, the intensity of reflected light changes, which causes a problem of malfunction.
In order to prevent this, there is a method to reduce the influence of the ripple by using a peak holding circuit for the output signal. However, the sensitivity is not sufficient because the signal output (base line) in a normal state without an oil film becomes large. The problem that a trace amount of oil cannot be detected remains.

The (3) hexane extraction / gravimetric method and the (4) extraction / infrared absorption measurement method have a problem that continuous automatic monitoring is difficult. These methods are based on JIS K0101, JIS
-Although it is a method specified in K0102, pre-processing of extraction is necessary, and even if complicated operations are automated, the mechanism is complicated and maintenance is difficult, and waste liquid must be treated. Therefore, it is not suitable for continuous automatic measurement.

(5) The method of measuring emulsification and turbidity is that, if there is a floating oil, instant emulsification is difficult to be performed even by ultrasonic irradiation, and that the emulsified oil deteriorated due to heat history is not stable in particle size.
In addition, there is a problem that the measurement error increases due to the influence of the presence of a turbid substance in the sample on the measured value, and the detection of a trace amount of oil cannot be performed. (6) Since the fluorescence measurement method requires a certain amount of oil to detect weak fluorescence emitted from oil, it is difficult to detect a trace amount of oil. Further, there is a problem that it cannot be detected by fluorescence depending on the type of oil such as deteriorated oil.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to reduce a very small amount of oil flowing into a water purification plant, an aquaculture plant, or a very small amount of oil discharged from a factory drainage facility. It is an object of the present invention to provide an oil film detecting device which continuously and accurately monitors with sensitivity.

[0012]

In order to solve the above-mentioned problems, the present invention provides an oil film detecting device utilizing the following four means using the P-polarized light component and the S-polarized light component of irradiation light. I do. In the first apparatus of the present invention, a light projecting means for irradiating a light beam containing both a P-polarized component and an S-polarized component to a water surface on which an oil film floats, and a P-polarized component and an S-polarized component reflected from the water surface Polarization separating means, photoelectric conversion means for converting the separated amounts of the P-polarized component and S-polarized component into electric signals, and the light amounts of the P-polarized component and the S-polarized component based on the signal output from the photoelectric converting means. The arithmetic means for calculating the ratio and the comparing means for comparing the calculated output with a normal reference value with no oil film on the water surface are employed as technical means.

In a second apparatus of the present invention, a light projecting means for irradiating a light beam containing both a P-polarized light component and an S-polarized light component to a water surface on which an oil film floats, and a light reflected from the water surface as a P-polarized light component A polarized light separating means for separating the light into an S polarized light component,
Photoelectric conversion means for converting the light amounts of the polarized light component and the s-polarized light component into electric signals; and comparing the reflected light amounts of the p-polarized light component and the s-polarized light component with a normal reference value based on the signal output from the photoelectric conversion means. The comparing means and the judging means for judging that only the reflected light amount of the S-polarized component has increased compared to the normal state are employed as technical means.

According to a third aspect of the present invention, there is provided a light projecting means for alternately irradiating a light beam having a P-polarized component and a light beam having an S-polarized component to a water surface on which an oil film floats, and a P-polarized light reflected from the water surface. Photoelectric conversion means for converting the amounts of the reflected light of the component and the reflected light of the s-polarized component into electric signals, and calculating means for calculating the light quantity ratio between the p-polarized component and the s-polarized component based on the signal output from the photoelectric conversion means And a comparing means for comparing the operation output with a normal reference value are employed as technical means.

According to a fourth aspect of the present invention, there is provided a light emitting means for alternately irradiating a light beam having a P-polarized component and a light beam having an S-polarized component to a water surface on which an oil film floats, and a P-polarized light reflected from the water surface. Photoelectric conversion means for converting the amounts of the reflected light of the component and the reflected light of the s-polarized component into electric signals, and the reflected light amounts of the p-polarized component and the s-polarized component based on the signal output from the photoelectric conversion means, respectively. The comparison means for comparing with the reference value and the judgment means for judging that only the reflected light amount of the S-polarized light component has increased compared to the normal state are adopted as technical means.

The first means of the present invention detects an oil film by utilizing the difference between the ratio of the P-polarized light component to the S-polarized light component of the reflected light on the water surface with and without the oil film. Light, which is an electromagnetic wave, is a transverse wave that oscillates in a plane perpendicular to the propagation direction, and thus directionally oscillates in that plane. The direction of the electric field vector of this vibration indicates the polarization characteristics. When the vibration is kept in a specific direction, the light beam is said to have a linear polarization characteristic, and when the light beam is not biased in a specific direction and changes irregularly in all directions, it is said to have a non-polarization characteristic. Further, a circular locus of the electric field vector is called circularly polarized light, and an elliptical one is called elliptically polarized light.

The polarization component of these arbitrary rays can be decomposed into two components perpendicular to the direction of propagation and perpendicular to each other. As in the first means of the present invention, a polarization component (P polarization component) parallel to a plane normal to the water surface set at a point where the incident optical axis intersects with the water surface and a plane including the incident optical axis (P polarization component) and a polarization component perpendicular to the plane including the incident optical axis (S In order to irradiate a light beam containing both components (polarization component) simultaneously, irradiate a light beam of non-polarization characteristic or circular polarization characteristic, or irradiate a light beam of linear polarization characteristic with the polarization direction of the incident optical axis and the water surface. Inclined with respect to the plane containing the normal (for example, 45
°). FIG. 5 shows the mutual relationship between the water surface, the incident light, the P polarization plane, and the S polarization plane.

It can be considered that the P-polarized light component and the S-polarized light component are independently reflected on the water surface. The intensity of the reflected light is defined by the reflection coefficient of Fresnel, and varies independently depending on the angle of incidence of the light beam and the refractive index (or dielectric constant) of the medium. Therefore, if an oil film exists on the water surface, the P-polarized light component and S
The reflected light intensity of the polarization component changes independently. Therefore,
When the P-polarized light component and the S-polarized light component of the reflected light are separated, the respective reflected light intensities are measured, and when the ratio is taken, the value changes depending on the presence of the oil film, whereby the oil film can be detected.

The feature of this means is that it is an optical measurement, so that an oil film can be easily and continuously detected without requiring complicated operations. To detect the oil film with high sensitivity. If the water surface is wavy or foreign matter floats, irregularly reflected light is generated. Therefore, if only the intensity of the reflected light is monitored, the intensity changes and stable measurement cannot be performed, resulting in a decrease in sensitivity.

On the other hand, if the ratio between the P-polarized component and the S-polarized component is monitored, even if the surface of the water ripples and the intensity of the reflected light changes, as long as the reflected light is received at a constant reflection angle, Since the ratio of the components is hard to change, stable and highly sensitive measurement can be performed. In addition, when there is a foreign substance floating on the water surface, the ratio of the S-polarized component divided by the P-polarized component becomes larger than that of water due to the presence of the oil film. In this case, since the polarized light is eliminated and the ratio becomes smaller, the difference between the oil film and the foreign matter can be determined. As described above, the oil film detecting device invented is hardly affected by the ripples on the water surface and the floating foreign matters, and can detect the oil film accurately and with high sensitivity.

According to the second means of the present invention, when the reflected light from the water surface is monitored at a certain range of light receiving angles, the S-polarized component of the reflected light increases due to the presence of the oil film, but the P-polarized component is constant or constant. The oil film is detected by utilizing the phenomenon of decrease. The light projecting unit, the polarization separating unit, and the photoelectric conversion unit of this unit measure the intensities of the P-polarized component and the S-polarized component of the reflected light, respectively, as in the first unit of the present invention. When an oil film is present on the water surface, the reflected light intensities of the P-polarized light component and the S-polarized light component change independently of each other due to the difference in the refractive indexes of the oil and water. become.

The S-polarized light component has a vibration direction parallel to the water surface, and generates reflected light by vibrating the electric charge of the water molecule in a direction parallel to the water surface. The effect is greater when the medium has a large refractive index, and in the case of an oil film, the intensity of the reflected light increases. On the other hand, the P-polarized light component oscillates in a plane perpendicular to the water surface, and only the oscillating component of the electric charge in the same direction as the oscillating direction of the reflected light contributes to the amount of reflected light. Therefore, the effect changes depending on the reflection angle. When the angle between the water surface and the incident optical axis is small (when the incident angle is large), the intensity of the reflected light is constant or decreases when the oil film has a higher refractive index. Therefore, an oil film can be detected based on this difference.

This second means can detect the oil film in the same manner as the first means of the present invention, but "increases the S-polarized component".
And the "fixed or decreased P-polarized component" condition is determined only as an oil film. Therefore, it is less likely that a non-oil film is erroneously determined as an oil film. The third means of the present invention, like the first means, uses the P of reflected light on the water surface with and without the oil film.
The oil film is detected by utilizing the difference between the ratio of the polarized light component and the S polarized light component. The difference from the first means is that a light beam having a P-polarization characteristic and a light beam having an S-polarization characteristic are alternately irradiated, and the intensities of the P-polarization component and the S-polarization component of the reflected light are measured by one photoelectric converter. This is characterized in that the measurement is performed, and the polarization separation means is omitted.

According to the fourth means of the present invention, similarly to the second means, when the reflected light from the water surface is monitored at a certain range of light receiving angles, the S-polarized light component of the reflected light increases due to the presence of the oil film. However, the oil film is detected using the phenomenon that the P-polarized component is constant or decreases. The difference from the second method is that
A light beam having a P-polarization characteristic and a light beam having an S-polarization characteristic are alternately irradiated, and the intensities of the P-polarization component and the S-polarization component of the reflected light are measured by one photoelectric converter. Thereby, the polarization separation means is omitted.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 shows an oil film detecting device as a first embodiment of the present invention. Using a laser light source 1 having circular polarization characteristics, a P-polarized component (in the figure, the vibration direction 2 of the P-polarized component is used).
Are shown by upper and lower arrows) and an S-polarized component (in the figure, indicated by a circle with a black dot around the oscillation direction 3 of the S-polarized component), is a wave that floats on the oil film 5. The water surface 6 is irradiated obliquely at a certain incident angle 7 (the incident angle 7 is the angle between the normal 9 of the water surface and the incident optical axis 8 at the point where the incident optical axis 8 intersects the water surface 6). . After the optical path of the reflected light 10 from the water surface 6 is restricted by the pinhole 11, the reflected light 10 is passed through a polarizing beam splitter 12, and a P-polarized component 13 and an S-polarized
And 4. The separated P-polarized light component 13 and S-polarized light component 14 are photoelectrically converted by a photodiode 15 and a photodiode 16, respectively, and each light amount is converted into an electric signal.

Each electric signal is supplied to an amplifier 17 and an amplifier 18.
And then input to the arithmetic circuit 19. The arithmetic circuit 19 calculates and outputs the light amount ratio between the P-polarized component and the S-polarized component based on the input signal. The comparator 20 detects that the signal branched from the amplifier 18 is lower than the reference voltage 21 and outputs a signal. The hold circuit 22 is an arithmetic circuit 19
Is held in accordance with the signal output of the comparator 20. This is because the reflected light 10 does not reach the photodiode 16 due to the optical path limitation of the pinhole 11 and the amplifier 1
This is a process for holding the signal of the arithmetic circuit 19 and invalidating the signal when the signal level of the signal 8 has dropped.
After the signal output from the hold circuit 22 is moving averaged by the averaging circuit 23, it is input to the comparison circuit 24. Comparison circuit 2
Reference numeral 4 compares an input signal with a reference value 25 corresponding to a normal state where there is no oil film on the water surface, and when it exceeds a predetermined range, determines that there is an oil film and outputs an alarm 26 to the outside.

Table 1 shows the ratio of the amount of reflected light between the P-polarized light component and the S-polarized light component when the water surface having no oil film, the water surface on which various oil films float, and the water surface on which foreign matter floats were measured by the apparatus of Example 1. Show data. The measurement in this table shows that the wavelength of the laser light is 6
33 nm, the incident angle is 70 °, and the thickness of the oil film is 0.5 to 50 μm.

[0028]

[Table 1] The ratio of the amount of reflected light between the P-polarized component and the S-polarized component is 1.2 to 1.7 times as large as when there is no oil film, and it can be seen that the presence or absence of a small amount of oil film can be sufficiently detected. In addition, the ratio of the amount of reflected light between the P-polarized component and the S-polarized component is 0.3 to 0.3.
It is clear that it is as small as 0.4 times, and it is possible to discriminate between the oil film and the foreign matter.

The data in Table 1 is for the case where the incident angle is 70 °, and will be described below for other incident angles. FIG. 6 shows a water surface without an oil film and a refractive index of 1.5,
The change of the reflected light amount ratio of the S-polarized light component and the P-polarized light component with respect to the incident angle on the water surface where the oil film having a thickness of 1 μm floats is shown. The reason why the data near the incident angle of 45 ° to 60 ° is over-scaled and does not show a specific numerical value is that the reflection intensity of the P-polarized component is extremely small and the measurement error is large in this vicinity. FIG. 6 shows that the measurement difference between the case with and without the oil film is large at the incident angle of 60 ° to 90 °, and it is understood that the oil film can be detected efficiently when measured at the incident angle in this range.

FIG. 7 shows a signal processing process when the water surface is shaking. This figure shows (1) the output of the amplifier 16 indicating the intensity of the P-polarized component of the reflected light, (2) the output of the amplifier 17 indicating the intensity of the S-polarized component, and (3) the P-polarized component and the S-polarized component. , The output of the arithmetic circuit 19, the output of the hold circuit 21, and the output of the average arithmetic circuit 25 are shown. Due to the fluctuation of the water surface, (1) the intensity of the P-polarized component and (2) the intensity of the S-polarized component are largely disturbed, but (3) the intensity ratio of the P-polarized component and the S-polarized component is small. (4) The output of the hold circuit is more stable, and the output signal of the final processing (5) average operation circuit 25 is hardly disturbed. This indicates that the oil film can be accurately detected even if the water surface shakes.

As described above, since the apparatus of the first embodiment of the present invention is an optical measurement, it can easily and continuously detect an oil film without requiring a complicated operation, and also has an advantage in that the water surface has a wavy shape. It is hardly affected by floating foreign substances, and can detect oil film accurately and with high sensitivity. In the example of FIG. 7, a laser light source having a circular polarization characteristic is used as the light source. However, a laser light source having a non-polarization characteristic may be used. However, a commercially available non-polarization laser light source has the intensities of the P polarization component and the S polarization component. Often changes with a period of several seconds, in which case it is necessary to correct the light amount.
Also, the linearly polarized laser light source is inclined with respect to a plane whose polarization direction includes the incident optical axis and the normal to the water surface (for example, 45 degrees).
°). In this case, if the tilt angle changes, the intensities of the P-polarized component and the S-polarized component change.
It is necessary to confirm each initial light amount.

When the fluctuation of the water surface is small, a pinhole 11 for limiting the optical path of the reflected light and a comparator 20 for invalidating the signal output during the period when the reflected light is blocked.
And the holding circuit 22 and the averaging circuit 23 are not necessary,
What is necessary is just to input the output of the arithmetic circuit 19 to the comparison circuit 24 as it is. [Embodiment 2] Fig. 2 shows an oil film detecting apparatus according to a second embodiment of the present invention.

In this figure, the same components as those shown in FIG. 1 indicate the same components. In this embodiment, as in the first means of the present invention, the intensity of the P-polarized component of the reflected light is output from the amplifier 17 and the intensity of the S-polarized component is output from the amplifier 18, and the signal from the amplifier 17 is compared. Circuit 27
The signal from the amplifier 18 is input to the comparison circuit 28. The comparison circuit 27 compares the input signal with a reference value 29 corresponding to the intensity of the P-polarized light component in a normal state where there is no oil film on the water surface, and when the input signal is equal to or smaller than the reference value 29, the determination circuit 30 Output a signal. Comparison circuit 2
Reference numeral 8 compares the input signal with a reference value 31 corresponding to the intensity of the S-polarized light component in a normal state where there is no oil film on the water surface, and outputs a signal to the determination circuit 30 when the input signal becomes larger than the reference value 31. . The determination circuit 30 includes the comparison circuit 27 and the comparison circuit 2
ANDing the output signal of No. 8 and confirming that only the intensity of the S-polarized component has increased, it is determined that there is an oil film,
An alarm 26 is output to the outside.

FIG. 8 shows a water surface without an oil film and a refractive index of 1.5,
For each of the floating surfaces of the 1 μm thick membrane film,
The change of the reflected light amount of the S-polarized light component and the P-polarized light component with respect to the incident angle is shown. In the range of the incident angle of 60 ° to 90 °, the light amount of the P-polarized light component is not different between the case with and without the oil film, whereas the light amount of the S-polarized light component is large with the oil film. . The device of the second embodiment can detect the oil film in the same manner as the device of the first embodiment, but only when the two conditions of “increase in the S-polarized component” and “constant or decreased P-polarized component” are satisfied. Since an oil film is determined, it is less likely that a non-oil film is erroneously determined to be an oil film. [Embodiment 3] FIG. 3 shows an oil film detecting apparatus according to a third embodiment of the present invention.

In this figure, the same components as those shown in FIGS. 1 and 2 indicate the same components. In this embodiment, the P-polarized light beam emitted from the linearly polarized laser light source 32 and the S-polarized light beam emitted from another linearly polarized laser light source 33 are sufficiently compared with the period of the wave on the water surface. The light is alternately lit by ON / OFF modulation at a fast cycle, and is coaxially illuminated with the mirror 34 and the half mirror 35 to irradiate the water surface 6. The reflected light 10 from the water surface 6 is directly photoelectrically converted by the photodiode 15, and the amounts of the P-polarized component 13 and the S-polarized component 14 are converted into electric signals in synchronization with the ON / OFF modulation of the light beam. The subsequent signal processing is the same as in the first embodiment. The feature of this embodiment is that the polarization beam splitter 12 is omitted and one photodiode 15 measures the amounts of light of the P-polarized light component 13 and the S-polarized light component 14. Can be Fourth Embodiment FIG. 4 shows an oil film detecting device according to a fourth embodiment of the present invention.

In this figure, the same components as those shown in FIGS. 1, 2 and 3 represent the same components. In this embodiment, similarly to the third embodiment, the laser light source 32 and the laser light source 33 are used to alternately irradiate a light beam having a P-polarization characteristic and a light beam having an S-polarization characteristic so that the P-polarized light The intensity of the component and the S-polarized component was measured by one photoelectric converter 15. The signal processing is the same as in the second embodiment. The feature of this embodiment is that, similarly to the third embodiment, the polarization beam splitter 12 is omitted and one photodiode 15 is omitted.
Is used to measure the amounts of light of the P-polarized light component 13 and the S-polarized light component 14, and the same performance as in the second embodiment can be obtained.

Although the method of installing the oil film detecting device is not shown in the drawings of the first to fourth embodiments, the oil film detecting device is fixed around the water tank where the water level does not change. It is possible to adopt a method of placing it on the water surface by placing it on the water. Also, when there is an influence of disturbance light such as sunlight, an interference filter that passes only the wavelength of the projected beam is provided in front of the photoelectric converter in the light receiving unit, or the modulated modulated beam is used to modulate only the modulation frequency. The influence of disturbance light can be eliminated by selecting the signal in the signal processing unit.

[0038]

The oil film detecting device according to the present invention relates to an oil film detecting device for automatically detecting an oil component flowing into a water purification plant, a farm, or an oil component flowing out of a factory drainage facility as an oil film on the water surface. , The problems of conventional equipment, the difficulty of continuous automatic measurement, the difficulty of detecting trace amounts of oil,
It is designed to solve the problem of many malfunctions. The ratio of the P-polarized component and the S-polarized component of the light reflected on the water surface with and without the oil film is different. The oil film is detected using the phenomenon that the S-polarized component increases but the P-polarized component increases or decreases, so it is simple, continuous, and highly sensitive and accurate without being affected by the ripples or floating foreign substances on the water surface. The oil slick can be detected.

[Brief description of the drawings]

FIG. 1 is a schematic view of a first invention example of an oil film detection device.

FIG. 2 is a schematic view of a second invention example of an oil film detection device.

FIG. 3 is a schematic view of a third invention example of an oil film detection device.

FIG. 4 is a schematic view of a fourth invention example of an oil film detection device.

FIG. 5 is a diagram showing a mutual relationship between a water surface, incident light, a P-polarized surface, and an S-polarized surface.

FIG. 6 is a diagram illustrating a change in the ratio of the amount of reflected light of the S-polarized light component and the reflected light amount of the P-polarized light component to the incident angle on the water surface without an oil film and the water surface on which the film film floats

FIG. 7 is a diagram showing a signal processing process when the water surface is shaking.

FIG. 8 is a diagram illustrating a change in the amount of reflected light of an S-polarized component and a P-polarized component with respect to an incident angle on a water surface having no oil film and a water surface on which the film film floats.

[Explanation of symbols]

 1: laser light source 2: oscillation direction of S-polarization component 3: oscillation direction of P-polarization component 4: light beam 5: oil film 6: water surface 7: incident angle 8: incident optical axis 9: normal to water surface 10: reflected light 11 : Pinhole 12: Polarization beam splitter 13: P polarization component 14: S polarization component 15: Photodiode 16: Photodiode 17: Amplifier 18: Amplifier 19: Operation circuit 20: Comparator 21: Reference voltage 22: Hold circuit 23: Average Arithmetic circuit 24: Comparison circuit 25: Reference value 26: Alarm 27: Comparison circuit 28: Comparison circuit 29: Reference value 30: Judgment circuit 31: Reference value 32: Laser light source 33: Laser light source 34: Mirror 35: Half mirror

Continuation of the front page (72) Inventor Yoshiharu Tanaka 1-1-1 Tanabe Shinda, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fuji Electric Co., Ltd.

Claims (8)

[Claims] 1. A polarization component (hereinafter referred to as a P-polarization component) parallel to a plane including the normal line of the water surface and the incident optical axis, which is set at a point where the incident optical axis intersects the water surface, on the floating water surface of the oil film. A light projecting means for irradiating a light beam containing both components of a polarization component perpendicular to the plane (hereinafter, referred to as S-polarization component), and polarization separation for dividing the reflected light from the water surface into a P-polarization component and an S-polarization component Means, photoelectric conversion means for converting the light amounts of the separated P-polarized light component and S-polarized light component into electric signals, and calculation for calculating the light amount ratio between the P-polarized light component and the S-polarized light component based on the signal output from the photoelectric conversion means. Means, and comparing means for comparing the operation output thereof with a reference value in a normal state where there is no oil film on the water surface,
An oil slick detection device that determines the presence or absence of an oil slick on the water surface from the comparison result. 2. A light projecting means for irradiating a light beam containing both a P-polarized light component and an S-polarized light component to a water surface on which an oil film floats, and dividing light reflected from the water surface into a P-polarized light component and an S-polarized light component. Polarization separation means, photoelectric conversion means for converting the light amounts of the separated p-polarized light component and s-polarized light component into electric signals, and reflection light amounts of the p-polarized light component and the s-polarized light component based on the signal output from the photoelectric conversion means. Comparing means for comparing with a reference value in a normal state, and determining means for determining that only the reflected light amount of the S-polarized component has increased compared to the normal state, and determining the presence or absence of an oil film on the water surface from the determination result Oil film detector. 3. A light projecting means for alternately irradiating a light surface having a P-polarization characteristic and a light beam having an S-polarization characteristic to a water surface on which an oil film floats; Photoelectric conversion means for converting the quantity of reflected light of the polarized light component into an electric signal; calculating means for calculating a light quantity ratio between the P-polarized component and the S-polarized component based on the signal output from the photoelectric conversion means; An oil film detecting device, comprising: a comparing means for comparing with a normal reference value having no oil film on the water surface, and judging the presence or absence of an oil film on the water surface from the comparison result. 4. A light projecting means for alternately irradiating a light surface having a P-polarization characteristic and a light beam having an S-polarization characteristic to a water surface on which an oil film floats; A photoelectric conversion means for converting the quantity of reflected light of the polarized light component into an electric signal, and a comparison for comparing the reflected light quantity of each of the P-polarized component and the S-polarized component with a normal reference value based on the signal output from the photoelectric conversion means; An oil film detecting device comprising: means for determining that only the reflected light amount of the S-polarized component has increased as compared to a normal state, and from the result of the determination, the presence or absence of an oil film on the water surface. 5. An apparatus according to claim 1, wherein said light path restricting means blocks light reflected at an angle out of a prescribed range with respect to an incident optical axis, and all or part of the reflected light is blocked. An oil film detection device comprising: a signal processing unit that invalidates the signal output when the signal output from the photoelectric conversion unit becomes smaller than a predetermined value. 6. An apparatus according to claim 1, wherein an angle between a normal line of the water surface, which is set at a point where the incident optical axis intersects the water surface, and the incident optical axis (hereinafter, referred to as an incident angle) is 60 °. The oil film detecting device described above. 7. An oil film according to claim 1, wherein a circularly polarized laser light source is used as a light projecting means for irradiating a light beam containing both a P-polarized component and an S-polarized component. Detection device. 8. An apparatus according to claim 1, wherein a laser light source having a linear polarization characteristic is used as a light projecting means for irradiating a light beam containing both a P-polarized light component and an S-polarized light component, and the polarization direction is incident light. 4 for the plane containing the axis and the normal to the water surface
An oil film detecting device, wherein the angle is set to 5 °.