Optical sensor unit and wetting determination device using it, and measurement method of wet state

Abstract

To provide an optical sensor unit and a wetting determination device for monitoring a wet state by liquid on the surface of a measurement object such that liquid, such as water on the surface, dries up, and to provide a measurement method of a wet state.SOLUTION: By vertically applying circularly polarized irradiation light 21 having a high water-absorption ratio to a water surface (interface) 72 for covering a measurement object, reflection light 22 from the measurement object is received as detection light 23. When a water film having a predetermined thickness exists on the surface of a measurement object, much of the irradiation light returns to an optical sensor unit 10 as reflection light 22 as it is and is detected as detection light 23 by total reflection when circularly polarized irradiation light is applied to the water surface vertically, but the irradiation light 21 is reflected irregularly and the detection light 23 decreases rapidly when the amount of water becomes small and the surface is exposed. Accordingly, a state in which the amount of water on the surface of a measurement object becomes small can be detected reliably immediately before drying up.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for detecting a change from a state in which the surface of a measurement target is covered with liquid to a state in which the liquid is removed, or vice versa. In particular, the present invention relates to an optical sensor unit and a wetness determination device for measuring a wetness state, which represents a state in which a surface having irregularities is completely covered with liquid, and a state in which the liquid on the surface is reduced to expose all or part of the surface irregularities, and a method for measuring the wetness state. Here, the liquid is not limited to water, but also includes oil and other liquids. [Background technology]

[0002] Concrete used in the construction of buildings and roads begins to harden immediately after it is poured. Hardening occurs due to a chemical reaction (hydration reaction) between the lime component of cement and water, and if there is a lack of moisture during the hardening process, the concrete may not achieve sufficient strength and may develop cracks after hardening. Therefore, during the concrete hardening process, it is necessary to provide sufficient moisture at appropriate times and to properly manage the temperature during hardening and the moisture state of the concrete surface. The quality of hardened concrete varies greatly depending on how the moisture state is managed from pouring to hardening (also known as curing management).

[0003] For this reason, in order to obtain the desired high quality concrete, curing management is performed by sprinkling water on the surface of the concrete for a certain period of time after pouring, and then covering the surface with a curing mat such as a vinyl sheet after the water sprinkling. In such curing management, it is necessary to replenish sufficient water so that there is no shortage of water necessary for the hydration reaction during the several days until the concrete hardens. By maintaining an appropriate moist state, it is possible to obtain concrete of the desired quality.

[0004] Conventionally, curing management after pouring ready-mix concrete has mainly been done manually. However, manual management entails burdens such as securing personnel with a certain level of experience and skills and management costs. Therefore, in order to reduce the burden of curing management, management using equipment that measures the amount of moisture on the surface has been proposed. For example, Patent Document 1 discloses a technology in which a sensor that detects the wetness is placed between the curing mat and the concrete to maintain a wet state using the curing mat.

[0005] However, curing management is preferably carried out by continuously replenishing water by appropriately sprinkling water so that the entire concrete surface is constantly covered with water, rather than covering it with a curing sheet as in Patent Document 1. On the other hand, when removing the curing sheet to replenish water, the amount of water lost to the outside due to evaporation increases, so it is necessary to constantly monitor the moisture condition of the concrete surface for several days and sprinkle water as appropriate. Therefore, when a curing sheet is not used, the burden of manually monitoring the moisture condition (wetness) of the concrete surface becomes particularly large.

[0006] In order to reduce the burden of such manual monitoring, there is a strong demand for a device that can automatically monitor the moisture state (wet state) of the concrete surface after casting. As a technology for measuring the moisture state of such concrete surfaces by a device, Patent Document 2 proposes a concrete wet curing device that uses an infrared moisture sensor to measure the moisture state contained in the inner wall surface of a tunnel and sprays water on the cast surface for curing the concrete after casting to keep it in an appropriate wet state. In addition, Patent Document 3 discloses a method for quantitatively measuring the moisture state of the painted concrete surface by near-infrared spectroscopy and determining the appropriate start time for rough surface finishing such as broom finish (see paragraph "0014" in the specification of Patent Document 3).

[0007] Furthermore, Patent Document 4 discloses an apparatus for testing the durability of concrete by sprinkling water on dry concrete, and then irradiating the concrete with near-infrared light of two wavelengths, one with a high moisture absorption rate and the other with a low moisture absorption rate, to measure the degree of moisture absorption (moisture absorption rate). Specifically, the concrete surface after water sprinkling is irradiated with light of two wavelengths and the reflected light of both irradiated lights is measured, and when the difference in the amount of received light (measured value) becomes almost "0", it is determined that there is no water on the concrete surface. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2018-3240 A [Patent Document 2] JP 2011-153497 A [Patent Document 3] Patent No. 6869769 [Patent Document 4] JP 2013-217676 A Summary of the Invention [Problem to be solved by the invention]

[0009] The above-mentioned Patent Documents 2 to 4 disclose a technique for measuring the moisture state of a concrete surface by irradiating it with near-infrared light and detecting the reflected light. However, these techniques do not measure the wetness state of the surface to be measured. Patent Document 2 describes a technique for measuring the moisture state contained in an inner wall surface by irradiating it with infrared light and measuring the strength of the reflected wave (see paragraph "0054" of the specification). However, it is difficult to accurately measure the transitional change in wetness state as the concrete surface goes from being covered to being completely exposed by simply irradiating it with infrared light.

[0010] Patent Document 3 describes that the moisture state is quantitatively measured using "near-infrared spectroscopy" (see paragraphs "0014" and "0016" of the specification), and that KJT-130 manufactured by Kett Corporation can be used as a near-infrared moisture meter (see paragraph "0016" of the specification). However, this device is intended to accurately measure the amount of moisture, and is a relatively large device with a complex structure. Therefore, when used for the purpose of constantly observing the wetness state of the surface of the measurement area for a long period of time, there are various problems in terms of being unsuitable for long-term continuous measurement, ensuring durability in a high humidity environment, high power consumption, complex data processing, difficulty in installing in multiple locations, and high manufacturing and operating costs.

[0011] The invention described in Patent Document 4 irradiates two types of light, measures, and compares the measured values, but the structure of the device and data processing are complicated, it takes time to process the measured data, and it consumes a lot of power. Therefore, like Patent Document 3, there are various problems in terms of long-term continuous measurement, durability, power consumption, data processing function, manufacturing and operating costs, etc., and it cannot be adopted.

[0012] The present invention has been made in consideration of problems in the prior art, such as the absence of a means for measuring a transient change state (or a transient progress state) of a wet state, such as concrete immediately after pouring, and provides an apparatus and method for monitoring the wet state of the surface of a monitoring object or a monitoring area with a simple structure. The present invention aims to provide an optical sensor unit capable of detecting a state immediately before liquid such as water disappears from the surface of a measurement object having irregular irregularities, such as the surface of concrete immediately after pouring, and to provide a wet state determination device that uses this optical sensor unit to monitor a transient change state in which the liquid covering the surface decreases and runs out, and to provide a method for measuring such a wet state.

[0013] In the above description of the problem of the invention, the problem of the invention was explained by exemplifying problems related to the wetness control of concrete after casting, from the viewpoint that the technology for controlling the wetness state of concrete immediately after casting is the most appropriate prior art for understanding the problem and usefulness of the present invention related to the wetness measurement technology. However, the present invention is not limited to the wetness control of concrete immediately after casting, and can also be applied to management of prevention of liquid depletion, management of liquid leakage, management of rainfall, and other uses. [Means for solving the problem]

[0014] In order to achieve the above-mentioned object of the invention, an optical sensor unit according to a first aspect of the present invention comprises a light source that emits laser light having a wavelength in the near-infrared region, an optical system that irradiates a surface having projections and recesses to be measured with irradiation light obtained by polarizing the laser light emitted from the light source, and a light receiving element that receives reflected light of the irradiation light irradiated from the optical system and outputs an electrical signal according to an amount of the reflected light received, and the optical sensor unit measures a wet state of a liquid covering the surface based on the amount of the reflected light received, The optical system includes: a collimator lens that converts the laser light beam emitted from a light source into parallel light; a beam splitter that transmits either the P-polarized component or the S-polarized component of the laser light emitted from the light source and reflects the other polarized component; a quarter-wave plate provided downstream of the beam splitter, which gives a phase difference of 1 / 4λ to the laser light that has passed through the beam splitter and outputs the laser light as irradiation light; a condenser lens that condenses, as detection light, the reflected light of the irradiation light reflected from the measurement target location, which passes through the quarter wave plate, is input to the beam splitter in the opposite direction to the light source, and is split by the beam splitter; a light receiving element that receives the detection light focused by the focusing lens and outputs a measurement value according to an amount of received light, The laser light that has passed through the beam splitter is polarized by the quarter-wave plate into circularly polarized laser light, and the circularly polarized laser light is irradiated perpendicularly to the interface between the air and the liquid as the irradiation light, and the detection light extracted from the reflected light is measured.

[0015] Here, the shape and maximum height of the unevenness on the surface of the measurement object are not particularly limited, but it is preferable that the height is about several μm to 500 μm. When artificially providing unevenness on the surface of the measurement object, the height, shape, range, and density of the unevenness can be determined according to the type and structure of the measurement object and the purpose of the measurement. In the present invention, the irradiation light consisting of circularly polarized parallel light is irradiated onto the surface having unevenness at an angle perpendicular to the virtual interface between air and liquid, and the detection light in the reflected light is received by the light receiving element, converted into an electrical signal, and output. With this configuration, when the entire surface of the measurement object is covered with liquid, the output of the light receiving element is such that almost all of the irradiation light is totally reflected at the interface, and the reflected light returns at the same angle as the incident angle. Therefore, most of the reflected light returns to the 1 / 4 wave plate through which the irradiation light passed, and enters the 1 / 4 wave plate from the opposite direction. Therefore, when the surface of the measurement object is covered with liquid, most of the reflected light of the irradiation light is detected by the light receiving element as detection light.

[0016] On the other hand, when a part of the surface of the measurement object begins to be exposed, the unevenness of the surface of the measurement object protrudes from the liquid surface and appears in the air, so the reflected light of the irradiated light on the uneven surface is scattered and does not return in the direction of the quarter-wave plate. Therefore, when a part of the unevenness of the surface of the measurement object begins to be exposed, the amount of received detection light decreases rapidly, making accurate detection possible. The optical sensor unit may also be equipped with an amplifier circuit that amplifies the output of the light receiving element and a conversion circuit to a digital signal.

[0017] In this way, by irradiating the circularly polarized light perpendicularly to the air-liquid interface (horizontal surface), the circularly polarized light is almost totally reflected at the interface when the wetness is 100%, and is input to the light receiving element as detection light, so the output of the light receiving element becomes large. On the other hand, when part of the unevenness of the surface of the measurement target is exposed, most of the irradiation light irradiated to the exposed unevenness is scattered and does not become detection light, and does not reach the light receiving element. Also, part of the scattered reflected light is absorbed by the liquid, so the detection light detected by the light receiving element decreases. For example, in the case of ready-mix concrete, where the maximum height of the unevenness is much smaller than 500 μm, the remaining moisture is extremely low at the stage when part of the surface begins to be exposed. Therefore, when part of the surface is exposed, the rate of moisture loss due to evaporation also increases, and the measurement value drops rapidly. The unevenness may be formed naturally or artificially.

[0018] Furthermore, it is preferable that the irradiated light is light with a wavelength that is highly absorbed by the liquid covering the surface (for example, in the case of water, the wavelength is 1450 μm or 1940 μm, etc.). When part of the surface irregularities is exposed, part of the irradiated light and the reflected light (scattered light) from the exposed surface are incident on the liquid, and part of the light with a highly absorbed wavelength is absorbed by the liquid. This makes the difference in output from the light receiving element when it is completely covered by liquid and when it is partially exposed even more clear.

[0019] Furthermore, the light receiving element may be disposed at a position away from the focus of the condenser lens of the detection light, instead of at the focus. With this configuration, even if the irradiation angle of the irradiated light with respect to the interface varies slightly due to vibration or the like, it is possible to suppress large fluctuations in the measurement value by the optical element, and it is possible to measure changes in the wetness state more accurately.

[0020] In addition, the irradiation light is preferably a pulse train laser light with a low light emission duty. By configuring in this way, the power consumption and heat generation of the light source of the irradiation light can be reduced. In addition, since multiple pulse irradiation light are irradiated and judged, the influence of noise can be reduced, and more stable and accurate measurement of the wet state can be achieved.

[0021] A wetness determination device according to a first aspect of the present invention includes any one of the optical sensor units according to the present invention described above that irradiates the irradiation light onto a surface having projections and recesses to be monitored and outputs a measurement value; a control unit that controls the optical sensor unit to obtain the measurement values ​​of the monitored surface; a determination unit that determines a wet state of the monitoring target surface based on the measurement value acquired from the optical sensor unit and a predetermined criterion, and outputs a determination result; The present invention is characterized by comprising:

[0022] By using the optical sensor unit according to the present invention, which can sensitively detect the exposure of a part of the surface of the object to be monitored, it is possible to accurately detect the exposure of the surface irregularities, and quickly and reliably determine the wetness state of the surface. For example, when a part of a surface having small irregularities such as concrete becomes exposed, the measurement value or the rate of change of the measurement value changes suddenly, so it is possible to determine that the surface has entered a transitional change state in which the irregularities are partially exposed.

[0023] For example, if the measured value of the optical sensor unit drops by 20% or more from a wetness rate of 100%, it is considered that the remaining amount of liquid is very small because the unevenness is very small. Therefore, once the transitional change state is entered, there is a risk that the water or liquid will completely disappear (risk of depletion) in a relatively short time. For this reason, it is preferable to set a predetermined standard according to the monitoring target and monitoring purpose, and when the magnitude or change of the measured value reaches the predetermined standard, output a warning signal to prompt the necessary response. Based on this warning signal, it is possible to take various countermeasures, such as refilling the liquid.

[0024] For example, the determination unit can be configured to output a warning signal when the measurement value from the optical sensor unit falls below a predetermined threshold value, or to output a warning signal when the measurement value is within a predetermined range, or to set a plurality of ranges and output a different warning signal for each range. For example, by outputting the warning signal when the measurement value falls by 20% or more from the value when the entire surface of the monitored object is covered with liquid, it is possible to ensure a relatively long response time until the liquid completely disappears while ensuring measurement accuracy.

[0025] The determination unit may also be configured to include a calculation unit that calculates a change in the wetness state based on the changes and / or change rates of the multiple measurement values ​​measured at the predetermined time intervals, and to determine the wetness state based on the change calculated by the calculation unit and output the warning signal. By incorporating various factors into the determination, it becomes possible to make a more accurate determination.

[0026] In addition, a moving mechanism for moving the wetness determination device may be provided to make the wetness determination device movable. In this case, a control unit may be configured to control the moving mechanism and the optical sensor unit to move the wetness determination device within a predetermined measurement area and measure the wetness state at a plurality of measurement positions within the measurement area, and a determination unit may be configured to determine the wetness state of the measurement area based on the measurement values ​​at the plurality of measurement positions.

[0027] When the movable wetness determination device measures at a plurality of positions, the determination unit can be configured to output the warning signal in the measurement area when the measurement value in one or more of the measurement positions becomes equal to or less than the predetermined threshold value. When the remaining amount of liquid in any part of the measurement area becomes low, it is determined that the remaining amount in the entire measurement area is low.

[0028] Even when measurements are taken at a plurality of positions using a movable wetness determination device, the determination unit can output the warning signal for the entire measurement area or for a portion of the measurement area when the measurement value falls within a predetermined range at one or more of the measurement positions. Also, the determination unit can be configured to output a different warning signal for each different measurement range.

[0029] Furthermore, the determination unit may include a calculation unit that calculates a change value of the wetness state based on the changes and / or change rates of the multiple measurement values ​​measured at the predetermined time intervals, and may determine the wetness state based on the change value calculated by the calculation unit and output the warning signal. This makes it possible to issue a warning signal taking into consideration the changes and change rates at each measurement position as judgment factors.

[0030] A method for measuring a wet state according to a first aspect of the present invention includes irradiating a measurement object having an uneven surface with laser light having a wavelength in a near-infrared light region, and measuring a wet state of a liquid covering the surface of the measurement object using reflected light, the method comprising the steps of: an irradiation step of irradiating the surface of the measurement object with a laser beam consisting of parallel light of circularly polarized light having a wavelength of near-infrared light at an angle perpendicular to the interface between the air and the liquid; a light receiving step of receiving reflected light of the irradiation light with a light receiving opening that is concentric with the irradiation opening of the irradiation light; a branching step of branching the reflected light received by the light receiving opening as detection light; a measuring step of collecting the branched detection light by a collecting lens, receiving the light by a light receiving element, and outputting an electrical signal according to an amount of received light by the light receiving element; The present invention is characterized by comprising:

[0031] In the measurement process, the focused measurement reflected light can be received by the light receiving element arranged at a position away from the focal position of the focusing lens, and an electrical signal corresponding to the amount of light received can be output. Also, in the irradiation process, it is possible to irradiate light having a wavelength that is highly absorbed by the liquid as the irradiation light. Effect of the Invention

[0032] According to the optical sensor unit, wetness determination device, and wetness measurement method of the present invention, by irradiating the interface with circularly polarized laser light perpendicularly, when the wetness rate is 100%, strong reflected light due to total reflection from the interface can be measured as detection light. On the other hand, when the surface begins to be exposed, the total reflection area decreases, so the detection light decreases rapidly. Since the present invention can measure such a sudden change in the measurement value quickly and accurately with a simple configuration, it becomes possible to quickly determine the risk of depletion, which occurs when the wetness state of the surface of the measurement target changes and the measurement target becomes depleted.

[0033] According to the wetness determination device of the present invention, it is possible to accurately and quickly detect a decrease in the wetness of a surface before the entire surface of a measurement target such as concrete is completely exposed. In addition, when monitoring the remaining amount of liquid in a storage container, it is possible to accurately measure when the liquid has run out by providing a large number of minute projections and recesses of several μm or more (preferably about 10-100 μm) on a part or the entire surface of the bottom surface of the container that stores the liquid or other object to be measured. Conversely, it is also possible to use the device to accurately detect a change from a dry state to a wet state as necessary. [Brief description of the drawings]

[0034] [Figure 1] FIG. 2 is a diagram showing a schematic configuration of an optical sensor unit according to the present invention; [Diagram 2] 1 is an enlarged schematic diagram showing an example of a state in which light is irradiated onto a thin water film and unevenness with a portion of a concrete surface exposed, and an example of reflected light. [Diagram 3]This is a graph showing the measurement values ​​when circularly polarized and linearly polarized light of 1450 nm is irradiated from a fixed height (50 mm) on different concrete surfaces at different water depths. [Figure 4] A graph showing the measured values ​​obtained by measuring the change in water depth between 0 mm and 0.5 mm. [Diagram 5] 1 is a graph showing moisture absorption characteristics of near-infrared light. [Figure 6] This graph shows the amount of detected light received when a concrete surface that is completely covered in water 0.5 mm deep is irradiated with 1450 nm circularly polarized and linearly polarized light at different irradiation heights (irradiation distance and optical path length). [Figure 7] 13 is a graph showing measurement values ​​when linearly polarized light is irradiated onto the interface of a concrete surface at an irradiation angle shifted from the perpendicular. [Figure 8] 5A and 5B are diagrams showing a schematic diagram of a light receiving state and a profile of a received light waveform when the light receiving element 17 is placed at the focal position and when it is placed slightly shifted backward from the focal position. [Figure 9] This is a diagram that illustrates the relationship between irradiated light and total reflection as the water on the concrete surface gradually decreases until the water film completely disappears. [Figure 10] FIG. 2 is a functional block diagram of a wetness determination device according to an embodiment of the present invention. [Figure 11] FIG. 4 is a diagram illustrating a pulse train for driving a light source. [Figure 12] FIG. 1 is a diagram showing a schematic configuration of an embodiment of a wetness determining device using an MPU. [Figure 13] FIG. 1 is a diagram showing an example of a schematic configuration of the exterior of a movable wetness determining device. [Figure 14] This figure illustrates an optical sensor block equipped with an optical sensor unit to be mounted on a wetness determination device that measures while moving, where (a) shows a front view of the optical sensor block, and (b) shows a cross-sectional view along line AA' shown in (a). [Figure 15] FIG. 13 is a diagram showing a schematic diagram of a detection value and a moving average output when a measurement is performed while moving a measurement target area. [Figure 16]The graphs show measurements taken continuously while moving the measuring device in environments with different water depths, and (a) to (d) show the measurement values ​​taken on objects with different water depths (W) at the surface of the objects. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Hereinafter, with reference to the drawings, an optical sensor unit according to the present invention for monitoring the state of the liquid level covering the surface of a measurement object, and a wetness determination device and wetness inspection method using the same will be described. The optical sensor unit according to the present invention provides measurement data indicating whether or not a liquid is covering the surface of various monitoring objects having an uneven surface. The surface of concrete immediately after pouring has irregular unevenness with heights ranging from a few μm to a maximum of about 500 μm or less, and is the subject of measurement by the optical sensor unit of the present invention. By using this optical sensor unit, the wetness determination device of the present invention can accurately and quickly capture changes in the wetness state.

[0036] In this specification, a state in which the surface of the measurement area or measurement point is completely covered with liquid is defined as a wetness rate of 100% (the wetness rate is also referred to as a "wet state" as appropriate), and a state in which no liquid is present on the surface is defined as a wetness rate of 0% (0% wet state). A transitional change state in which liquid decreases from a wetness rate of 100% to a depleted (or dried) state of a wetness rate of 0%, or conversely, a transitional change state in which liquid increases from a dry state of a wetness rate of 0% to a surface completely covered with a wetness rate of 100%, is expressed as a wetness rate of 0% to 100%.

[0037] The wettability does not necessarily have to be an objective numerical value, and does not have to indicate the ratio of the amount of liquid to the surface area of ​​the measurement target, or the ratio of the surface area covered with liquid. In this specification, the wettability is measured by the device of the present invention when the surface of the measurement target is completely covered (100% wettability) and when there is absolutely no liquid on the surface (0% wettability), and these values ​​are used as reference values, and the ratio of the magnitude of the measured value to the reference value is used as the wettability. For example, if the measured value of a wettability of 100% when the surface is completely covered is "a", and the measured value of a wettability of 0% when no liquid has been removed from the surface is "b", and the measured value at the time of measurement is "c", then (1-(ac) / (a-b))x100=wettability (%).

[0038] In the present invention, the presence of a large number of irregularities on the surface of the measurement target area makes it possible to measure the wet state. The irregularities do not have to be present on the entire surface to be measured, but may be present only on a portion of the surface. As long as there are multiple irregularities in a certain area, measurement is possible using the present invention. The size, height, and shape of each of the multiple irregularities are not particularly limited, but it is preferable that there are multiple relatively small irregularities in a certain area of ​​the surface to be measured. The irregularities may be artificially created or may be naturally occurring, such as a concrete surface.

[0039] If the surface of the measurement target is completely smooth and without any irregularities, the measurement device of the present invention cannot perform measurement. When the measurement target has a smooth surface, measurement is possible by artificially creating irregularities on the surface of the measurement target (which may be only a part of the measurement area). The shape and height of the irregularities can be determined depending on the purpose of the irregularities. The uneven step surface may be a vertical step surface or a step surface with an incline. By providing irregularities with an inclined surface, it becomes possible to perform measurements in which the measurement value changes gradually in accordance with the rate of inclination in a transient change state.

[0040] In addition, by combining the stepwise change in height of the uneven protrusions, or the quantitative change in the number of unevennesses, the slope area, or the angle, it is possible to control the measurement accuracy and calculate the remaining liquid amount from the wettability. It is also possible to provide multiple uneven areas with different heights in one measurement area and measure each point.

[0041] As is clear from the above description, the scope of application of the optical sensor unit, wetness determination device, and wetness state measurement method of the present invention is not limited to curing management of concrete. For example, it is also possible to monitor whether the contained liquid has been depleted, and it is possible to use various liquids and various applications. In the following description, wetness management (curing management) of the concrete surface immediately after pouring is used as an example, but the present invention is not limited to these applications.

[0042] An optical sensor unit for monitoring a concrete surface, a wetness determination device, and a method for measuring a wet state according to an embodiment of the present invention will be described below with reference to the drawings. Fresh concrete is in a fluid state immediately after pouring, but as the hydration reaction progresses, the water on the surface of the concrete disappears, and the concrete becomes soft and viscous like clay, gradually hardening. During the few days it takes for the concrete to go from a soft and viscous state to a state where it develops the desired strength, a lot of water is needed for the hydration reaction, and there is a tendency for water to be insufficient, so it is extremely important to supply sufficient water to obtain the desired quality.

[0043] Since poured concrete requires sufficient water to promote the hydration reaction for a certain period of time after the start of hardening, as mentioned above, it is desirable to spray water appropriately so that the entire concrete surface is thinly covered with water to a depth of about a few millimeters. In this way, a certain amount of water retained on the concrete surface will permeate into the concrete, ensuring the moisture necessary for the hydration reaction of the concrete after pouring.

[0044] On the other hand, the pouring surface of concrete has a large surface area, so the water sprayed is easily lost through evaporation. Therefore, in managing the water spraying of fresh concrete after pouring, it is necessary to constantly monitor the changes in the moisture content on the concrete surface and spray water appropriately before the moisture is depleted to maintain the moisture on the surface.

[0045] When the optical sensor unit of the present invention is used to monitor a concrete surface, the monitoring target is whether or not the concrete surface is covered with water. Hereinafter, in this specification, the term "water film" or "water film state" is used as appropriate to describe the state of water on the surface of a measurement target such as a concrete surface.

[0046] First, an optical sensor unit used in the wetness determination device according to the present invention will be described. The optical sensor unit according to the present invention is a device that irradiates a circularly polarized irradiation light generated by adjusting a laser light in the near infrared region perpendicularly to a monitoring target location, receives the reflected light in a predetermined area, and outputs the received detection light as an electrical signal. The output of the optical sensor unit according to the present invention changes suddenly when the wetness state changes transiently from 100% to less than that (or vice versa, when the wetness state changes from 0% to 100%). Therefore, by measuring the output, it is possible to accurately capture the transient change state in which the wetness state changes suddenly, and it is suitable for use as a sensor for a wetness monitoring device, etc.

[0047] 1 is a schematic diagram for explaining the basic concept of the optical sensor unit according to the present invention. As an example, an optical sensor unit 10 is shown which irradiates light onto a concrete surface 70 covered with a water film 71 and measures the reflected light.

[0048] When viewed magnified, the surface of concrete has irregular, minute irregularities. However, for the sake of convenience, the term may be used to mean a smooth imaginary surface that averages the uneven surface. For this reason, in this specification, the averaged smooth imaginary surface is indicated with the number "70" attached, such as "concrete surface 70". On the other hand, when the minute irregularities or inclined surfaces of the concrete surface are problematic, the number "70" is followed by an alphabetic symbol, such as "concrete surface 70a," for explanation.

[0049] In this specification, the light irradiated to the measurement object (or monitoring object) is referred to as "irradiated light", and the light reflected from the liquid surface or the measurement object is referred to as "reflected light". Furthermore, of the "reflected light", the reflected light that enters the optical sensor unit from the opposite direction to the irradiated light, is branched, and is received by the optical element is referred to as "detection light". Furthermore, "liquid" includes oil other than water and other liquids that do not contradict the essential functions of the present invention.

[0050] With reference to Fig. 1, the basic configuration of an optical sensor unit according to an embodiment of the present invention will be described. In the optical sensor unit 10 shown in Fig. 1, a laser beam having a wavelength of linearly polarized near-infrared light is emitted from a light source 11. The emitted light 20 emitted from the light source 11 is irradiated perpendicularly to an irradiation target area as a beam-shaped irradiation light 21 of circularly polarized parallel light after passing through a predetermined irradiation optical system. The emitted light 20 from the light source 11 is preferably near-infrared light, and more preferably light having a wavelength that is highly absorbed by the liquid to be measured (1450 nm or 1940 nm in the case of water, etc.) as described later. The irradiation light 21 is irradiated perpendicularly to an interface 72 between air and water (water surface).

[0051] The emitted light 20, which is a beam-like laser light emitted from the light source 11, is adjusted (collimated) by the collimating lens 12 to be parallel light, and is incident on a beam splitter (hereinafter referred to as "PBS") 13. The output of the emitted light 20 and the beam diameter of the irradiated light 21 can be appropriately determined based on the reflection characteristics of the surface or liquid to be measured, the light receiving sensitivity, the miniaturization of the device, and the measurement sensitivity. In order to perform accurate and stable measurement while suppressing power consumption, the beam diameter of the irradiated light is not particularly limited, but it is preferably about 1 mm to 5 mm, more preferably about 3 mm.

[0052] Moreover, by driving the light source 11 with a pulse train with a small duty ratio, it is possible to suppress power consumption. The measurement distance from the light source to the measurement object during measurement can be set appropriately depending on the application, but in the case of measuring the wetness of fresh concrete, it is preferably about 30 mm to 100 mm, and more preferably 50 mm or less and 30 mm or more. The beam diameter can be determined, for example, by an opening (irradiation opening) 15 as shown in FIG. 1.

[0053] PBS 13 is an optical element that separates incident light into S-polarized light and P-polarized light, reflects one of the S-polarized light or the P-polarized light, and passes the other. In the following example, PBS 13 will be described as having a function of cutting (reflecting) P-polarized light and passing S-polarized light. Emitted light 20, which is a beam-shaped linearly polarized laser light emitted from light source 11, is collimated by collimating lens 12, and the P-polarized light of output light 20 is cut (reflected) by PBS 13, and the parallel S-polarized laser light beam is incident on quarter-wave plate 14. Quarter-wave plate 14 is an optical element that gives a phase difference of 1 / 4λ to the incident light.

[0054] In the present invention, the S-polarized light that has passed through the PBS 13 is converted to circularly polarized light by the quarter-wave plate 14 to produce the irradiation light 21. As a result, the S-polarized outgoing light 20 that has passed through the PBS 13 is given a phase difference of 1 / 4λ by the quarter-wave plate 14, and is irradiated onto the concrete surface as beam-shaped irradiation light 21 consisting of circularly polarized parallel light. At this time, the irradiation light is irradiated onto the concrete surface 70 at an angle perpendicular to the interface between the air and the liquid surface (angle perpendicular to the horizontal plane). Note that the horizontal plane here is used as a concept that also includes a horizontal plane relative to artificially created gravity (e.g., centrifugal force, etc.).

[0055] Irradiation light 21 is a light beam consisting of a small diameter parallel light beam that is irradiated perpendicularly to the interface between the air and the liquid surface. When circularly polarized irradiation light 21 is irradiated perpendicularly to the interface, if an interface 72 exists, reflected light 22 is totally reflected and returns in the opposite direction at the same angle as irradiation light 21, and enters quarter-wave plate 14 from the opposite direction through the same opening 15 as irradiation light 21 (in this case, the "light receiving opening").

[0056] If we assume that the entire concrete surface 70 is covered with a water film 71 about several millimeters thick, the irradiated light 21 is irradiated perpendicularly to the air-water interface 72. Since the irradiated light 21 is a circularly polarized parallel light and is incident perpendicularly on the interface 72, the irradiated light 21 is totally reflected at the interface 72 and the reflected light 22 remains circularly polarized and enters the quarter-wave plate 14 from the opposite direction.

[0057] Circularly polarized reflected light 22 incident on the quarter-wave plate 14 from the opposite direction to the illumination light 21 is given a phase difference of 1 / 4λ by the quarter-wave plate 14 and converted into P-polarized laser light. That is, the S-polarized emitted light 20 that passes through the PBS 13 after emission passes through the quarter-wave plate 14 twice in a round trip, resulting in a phase shift of 90 degrees and becoming the P-polarized reflected light 22.

[0058] The P-polarized reflected light 22 does not pass through the PBS 13 but is reflected and branched, and is incident on the condenser lens 16 as detection light 23. The condenser lens 16 condenses the input detection light 23 toward a light receiving element (hereinafter referred to as "PD") 17, such as a photodetector. The PD 17 outputs an electrical signal according to the amount of received detection light 23 as a measurement value.

[0059] In the optical sensor unit 10, the collimator lens 12, the PBS 13, the quarter-wave plate 14, and the condenser lens 16 constitute an optical system 25. In the optical system 25, the collimator lens 12, the PBS 13, and the quarter-wave plate 14 constitute an irradiation optical system 25a, and the quarter-wave plate 14, the PBS 13, and the condenser lens 16 constitute a light-receiving optical system 25b.

[0060] As shown in FIG. 1, when the entire concrete surface 70 is covered with a water film 71, the circularly polarized irradiation light 21 is irradiated at a perpendicular angle to the interface 72. Since the irradiation light 21 is a circularly polarized parallel light beam, when the entire concrete surface 70 is covered with the water film 71, most of the irradiation light 21 is totally reflected (specularly reflected) and returns to the quarter-wave plate 14 as the reflected light 22 when the irradiation light 21 is irradiated perpendicularly to the interface 72. Therefore, when the entire concrete surface 70a is covered with a water film, a large amount of the detection light 23 is received by the PD 17, which becomes a relatively large detection light, and a large electrical signal (measurement value) is output. In contrast, when the surface unevenness is partially exposed, part of the irradiation light 21 is scattered by diffuse reflection from the exposed uneven surface of the concrete, and the reflected light 22 returning to the quarter-wave plate 14 is reduced, the detection light 23 is reduced, and the measurement value is reduced.

[0061] FIG. 2 is a partial enlarged schematic diagram illustrating the state of reflected light 22 when irradiation light 21 is irradiated onto a concrete surface in which the thickness of the water film 71 covering the concrete surface has decreased and part of the concrete surface 70a is exposed, and is a partially enlarged schematic diagram showing an enlarged portion of the area irradiated by irradiation light 21.

[0062] When observed under magnification at a level of 1000 to 2000 nm, which is the wavelength of the near-infrared light used as the irradiated light 21, the concrete surface 70a has many complex uneven surfaces with various angles. The irradiation area (irradiation beam) irradiated onto the concrete has a diameter of about 1 mm to 5 mm, which is approximately 1000 times larger than the wavelength of the irradiated light 21. FIG. 2 is a schematic diagram showing the irradiated light 21 and its reflected light 22, with a partially exposed concrete surface enlarged to show the state of the reflected light 22.

[0063] Even if a part of the surface is exposed, in the part where water remains, the irradiated light 21 is irradiated perpendicularly to the air-water interface 72. Therefore, the irradiated light 21 irradiated to the interface 72 is totally reflected and returns almost unchanged to the optical sensor unit as reflected light 22. However, the irradiated light 21 irradiated to the concrete surface 70a is reflected in a complex manner according to the inclination angle of the complex uneven surface of the concrete surface 70a, and is scattered in various directions, so that almost no reflected light 22 from the concrete surface 70a returns to the opening 15 of the optical sensor unit.

[0064] Therefore, when the surface dries and the interface 72 drops, exposing a large portion of the concrete surface 70a, the amount of detection light 23 decreases rapidly according to the exposed area of ​​the unevenness. If the height of the concrete unevenness is extremely small, the fact that some of the small unevenness of the concrete surface 70a is exposed means that the water depth is below the maximum height of the unevenness and is therefore extremely shallow. Therefore, when even a portion of the concrete surface 70a is exposed, the remaining water also rapidly decreases due to evaporation, and it can be understood that the water will be completely gone in a relatively short time.

[0065] Figure 3 is a graph showing the measured values ​​when a circularly polarized laser beam and a linearly polarized laser beam of 1450 nm are irradiated vertically from a height of 50 mm onto measurement points at different water depths. The measurements were performed at a temperature of 26°C to 27°C and a humidity of 55% to 56%. As can be seen from the graph, in the measured values ​​when irradiated with a circularly polarized laser beam, the output is 200 mV when the water depth is 0 mm, but when the water depth becomes 0.5 mm, the measured value changes to about 1400 mV, and even if the water depth increases from 0.5 mm thereafter, the measured value is maintained at a constant state (about 1400 mV) and shows almost no change.

[0066] This indicates that when the water depth is 0.5 mm or more, the unevenness of the concrete surface is completely covered with water, and the maximum height of the unevenness is within the range of 0 mm to 0.5 mm. It also indicates that when the water depth is 0 mm < water depth < 0.5 mm, the output changes rapidly from the time when the uneven surface begins to be exposed. From the measured values ​​in FIG. 3, it can be seen that when the unevenness of the surface is covered with water, the measured value is stable and hardly changes even if the water depth increases or decreases. This is because the circularly polarized irradiation light 21 is irradiated, and when the concrete surface 70a is covered with water, most of the irradiation light 21 is returned by total reflection regardless of the water depth, so a constant measured value is output.

[0067] In this way, by irradiating the surface with circularly polarized irradiation light 21, a stable measurement value (reference value) can be obtained when the surface is covered with water (liquid), and therefore, when the measurement value drops sharply from the reference value, it is possible to accurately determine that part of the unevenness of the surface of the measurement target has been exposed.

[0068] In contrast, when linearly polarized laser light is irradiated, the measurement value changes (decreases) gradually whether the water depth is in the range of 0 mm to 0.5 mm or 0.5 mm to 3.5 mm, and there is no sudden change due to the exposure of part of the unevenness. Therefore, with the measurement value of the reflected light by the linearly polarized laser light, it is difficult to capture the transient change state where part of the uneven surface is exposed as a clear change in the measurement value.

[0069] In Figure 3, measurements were not taken between 0mm and 0.5mm, so Figure 4 shows the changes in this range, divided into smaller intervals. However, because it is difficult to accurately set a water depth of 0.5mm or less, measurements were taken for a water depth less than 0.5mm (water depth <0.5mm), an even smaller water depth (<<0.5mm), and a water depth of 0mm, and the results are shown for each. Note that in Figure 4, the irradiation position (height) is 35mm, a slightly lower height than the measurements in Figure 3.

[0070] As can be seen from Figure 4, when the water depth is less than 0.5 mm (<0.5 mm), the measurement value (approximately 1900 mV) is the same as when the water depth is 0.5 mm or more, where the unevenness is covered with water. This measurement value shows that the concrete surface is covered with water even when the water depth is <0.5 mm. When the water depth becomes <<0.5 mm, the measurement value becomes approximately 1300 mV, and as the measurement value drops, it can be seen that some of the unevenness of the concrete surface is starting to become exposed. When the water depth drops from this state to 0 mm, the measurement value decreases further to 700 mV. Note that the reason the measurement value in Figure 4 is higher than that in Figure 3 is due to the difference in the amplification rate setting of the amplifier circuit.

[0071] In addition, it is preferable for the optical sensor unit 10 to use wavelengths belonging to near-infrared light, and it is even more preferable to use light with wavelengths that are easily absorbed by the liquid covering the surface (water in the case of concrete immediately after pouring). When scattered reflected light is received when part of the unevenness of the surface is exposed, light with a wavelength that has a high absorption rate is absorbed when it enters the liquid. Therefore, the detection light received after scattering and passing through the liquid becomes smaller, and the difference in output of the light receiving element between when the unevenness is completely covered and when it is partially exposed becomes clearer.

[0072] Fig. 5 is a diagram showing the absorption characteristics of near-infrared light by water. As shown in Fig. 5, near-infrared light with wavelengths of around 1450 nm and 1940 nm has the property that the absorption coefficient for water reaches a peak value, and light with wavelengths around the peak value has a lower absorption coefficient for water. Therefore, in the case of water, it is preferable to use light with a wavelength of 1450 nm or 1940 nm. In the following explanation, with certain exceptions, it is assumed that a wavelength of 1450 nm, which is a wavelength that is easily absorbed by water, is used as a light source.

[0073] Figure 6 is a graph showing the change in the measurement value when 1450 nm circularly polarized collimated light (parallel light) and linearly polarized collimated light are irradiated perpendicularly to the water surface at a depth of 0.5 mm, with the irradiation position (height = irradiation distance · optical path length) changed in the range of 40 mm to 60 mm. In the case of circularly polarized collimated light, the measurement value is almost uniform at about 2300 mV output even when the height is changed. This is because the circularly polarized collimated light is totally reflected at the water surface (interface). In contrast, with linearly polarized collimated light, the measurement value decreases as the irradiation position becomes higher, indicating that there is height dependency. This is because linearly polarized collimated light is not reflected at the water surface (interface), but enters the water and is reflected by the concrete surface below the water, but when reflected by the concrete surface, it is diffusely reflected.

[0074] Next, let us consider the effect on the measurement value when the irradiation angle of the laser light irradiated vertically is slightly deviated from 90 degrees. The graph in FIG. 7 shows the measurement value when the irradiation angle (elevation angle) of the interface 72 of the concrete surface is slightly deviated from the vertical, although it was measured with linearly polarized laser light. The water depth is 0 mm to 0.5 mm, where some of the unevenness of the concrete surface is slightly exposed, and the irradiation position is 50 mm. When vertical, the measurement value is 200 mV, and gradually changes up to an angle (elevation angle) of 4.5 degrees from the vertical, and becomes a constant value when the angle is more than that. From the measurement value in FIG. 7, it can be seen that measurement becomes difficult when the angle is deviated from the vertical by 4 degrees or more. Although there is a difference in the degree of elevation angle that can be measured, it is presumed that the effect of the deviation of the irradiation angle is similar to that of circularly polarized laser light.

[0075] As can be seen from the above explanation, in the optical sensor unit according to the present invention, it is preferable to irradiate the interface 72 with the circularly polarized parallel beam of irradiation light 21 perpendicularly. Furthermore, if this perpendicular irradiation state can be constantly maintained and the influence of external noise is small, it is preferable to place the light receiving element 17 at the focal position of the condenser lens 16, which has high light receiving sensitivity. However, it may not be possible to maintain the irradiation angle of the irradiation light 21 perpendicularly due to the influence of vibrations of the measurement device or the measurement target.

[0076] In particular, when the optical sensor unit 10 is moved to perform measurements at multiple measurement positions, the angle of the irradiated light changes subtly due to vibrations caused by the movement or unevenness of the moving floor surface. Therefore, it may not be possible to always irradiate the irradiated light 21 perpendicularly to the interface 72. If the irradiation angle is not perpendicular to the interface 72, the detected light will rapidly decrease, the measurement value of the light receiving element will decrease, and there is a risk of erroneous detection.

[0077] For example, in cases where it is difficult to always keep the irradiation angle of the irradiated light 21 vertical, such as when the optical sensor unit is moved during measurement, the light receiving element 17 of the optical sensor unit of the present invention may be configured to be disposed at a position slightly shifted from the focal position of the condenser lens 16. This makes it possible to reduce the risk of erroneous detection.

[0078] Fig. 8 is a diagram showing the relationship between the spread range of detection light 23 on light receiving element 17 and the intensity of the amount of received light when light receiving element 17 is placed at the focal position of condenser lens 16 and when it is placed slightly shifted from the focal position. Fig. 8(a) shows a waveform 61a indicating the spread range 61 of detection light 23 and the intensity of the amount of received light when light receiving element 17 is placed at the focal position, and Fig. 8(b) shows a waveform 62a indicating the spread range 62 of detection light 23 and the intensity of the amount of received light when the focal position is shifted backward from the focal position by about 1 mm.

[0079] If the light receiving element 17 is disposed at the focal position of the condenser lens 16, it is possible to efficiently obtain a measurement value corresponding to the amount of received detection light 23. However, on the other hand, when the light receiving element 17 is disposed at the focal position and receives light, it reacts sensitively to fluctuations in the detection light 23, so that the measurement value of the light receiving element 17 is significantly attenuated even if the irradiation angle of the irradiated light 21 to the interface 72 is shifted slightly due to a slight vertical movement of the light source position, etc. Therefore, even if the uneven surface is covered with water, the irradiation angle may be shifted due to slight vertical vibration, causing the measurement value to fluctuate significantly.

[0080] In contrast, if the light receiving element 17 is positioned slightly away from the focal position, the intensity of the received light (peak value) will be lower, but the beam profile will broaden, resulting in a beam profile in which the measurement value changes relatively gradually. When the beam profile broadens, the detection value does not change suddenly in a wide range around the peak value, so even if the angle changes slightly, there is little fluctuation in the detection amount. On the other hand, although the detection amount decreases when the light receiving element 17 is positioned slightly away from the focal position, the amount of detected light is large when the light is received after almost total reflection from an interface with a wetness rate of 100%. Therefore, even if the light receiving element 17 is positioned about 1 mm away from the focal position, it is possible to obtain a measurement value sufficient to detect the water surface (interface).

[0081] On the other hand, in the case of diffuse reflected light when there is little water film, the profile becomes wider and the amount of light detected becomes low. Therefore, even if the position of the light receiving element is shifted from the focus by about 1 mm, it is possible to obtain a measurement value that detects the interface, and it is possible to output not only a digital output of the "presence" / "absence" of the interface, but also an analog output of the measurement value. In this way, by arranging the light receiving element 17 slightly shifted from the focus position, it is possible to maintain stable measurement even if there is a risk that the irradiation angle of the irradiated light 21 to the interface 72 may be slightly deviated from the vertical direction due to vibration, etc.

[0082] In this way, by positioning the light receiving element 17 away from the focal position of the focusing lens 16, it is possible to prevent erroneous detection of exposed unevenness when, for example, measuring while moving the optical sensor unit.

[0083] Figure 9 is a diagram for explaining, as an image, the relationship between the irradiated light 21 (irradiated beam) and the total reflection at the water film (interface) as the amount of water on the concrete surface gradually decreases from a state where there is sufficient water on the surface until the water film completely disappears. Figure 9 (a) shows a state where there is sufficient water on the surface, (b) and (c) show a state where the amount of water gradually decreases, and (d) shows a state where there is no water on the surface at all. The thick horizontal line shows the interface 72 within the beam of the irradiated light 21, which indicates the boundary between the water film 71 and the air.

[0084] Since the region of this interface 72 is irradiated with a beam of circularly polarized illumination light 21 perpendicular to the interface 72, strong detection light is obtained by specular reflection (total reflection) (the reflected light 22 returns in the opposite direction to the illumination light due to total reflection.) As the unevenness becomes more exposed, this interface (water film) gradually decreases from (a) to (c) in Figure 9, and is almost completely absent in (d).

[0085] When the water film 71 is reduced and the number of horizontal interfaces 72 is reduced, even if a thin water film 71 is attached to the uneven surface of the concrete, the irradiated light 21 is not irradiated perpendicularly to the water film 71 on the uneven surface. Therefore, the irradiated light 21 passes through the thin water film 71 on the surface and is reflected by the concrete surface to become scattered light. Since the irradiated light 21 has a wavelength of 1450 nm, when it is incident on the water film 71 on the surface, some of it is absorbed by the water and then becomes scattered light. Since the scattered light does not return to the light receiving optical system 25b except for a very small portion, the measurement value is greatly reduced. When some of the unevenness is exposed in this way and the number of horizontal interfaces 72 is reduced, the detection light 23 is rapidly reduced due to this scattering and absorption by the water, and the measurement value becomes rapidly smaller.

[0086] Since the unevenness of the concrete surface is very small, it is considered that when the state shown in Fig. 9(b) is reached, the transition from (b) to (d) occurs in a very short time. When the beam diameter of the irradiated light is large enough compared to the unevenness of the concrete surface, the amount of light detected by the light receiving element 17 changes according to the exposure ratio, that is, how much of the uneven surface is exposed due to the reduction in the water film, and therefore it is possible to calculate the exposure ratio or wetness ratio of the concrete surface in a transitional change state based on the measurement value.

[0087] As is clear from the above explanation, the optical sensor unit of the present invention uses a wetness measurement method in which laser light with a wavelength in the near-infrared light region is adjusted to be circularly polarized, and is irradiated perpendicularly to the interface of a measurement object having an uneven surface, and the reflected light is measured to measure the wetness of the liquid covering the surface of the measurement object.

[0088] More specifically, this measurement method is characterized by comprising an irradiation step of irradiating the surface of the object to be measured with a circularly polarized laser beam having a wavelength of near-infrared light at an angle perpendicular to the interface between the air and the liquid; a light receiving step of receiving the reflected light of the irradiation light at a light receiving opening which is concentric with the irradiation opening of the irradiation light; a branching step of branching the reflected light received at the light receiving opening as detection light; and a measurement step of collecting the branched detection light with a collecting lens and receiving it with a light receiving element, which outputs an electrical signal according to the amount of light received.

[0089] In the measurement step, the collected reflected measurement light can be received by the light receiving element disposed at a position away from the focal position of the collecting lens, and an electrical signal corresponding to the amount of received light can be output, and in the irradiation step, light having a wavelength that is highly absorbed by the liquid can be irradiated as the irradiation light. This method can be applied even when the liquid has a large surface area and is not water.

[0090] Next, the configuration of a wetness determination device using an optical sensor unit according to the present invention will be described. Fig. 10 shows a functional block diagram of a wetness determination device according to an embodiment of the present invention. A wetness determination device 40 according to an embodiment of the present invention shown in Fig. 10 is composed of an optical sensor unit 10 and a determination unit 41. The wetness amount is determined by the determination unit 41 based on the measurement value measured by the optical sensor unit 10, and a determination signal, a warning signal, or the like is output according to the result.

[0091] 10, solid arrows indicate electrical signal or power connections, and dashed arrows indicate light. Note that the interface between the optical sensor unit 10 and the determination unit 41, and the interface for data input / output with the outside, are not shown. The determination unit 41 can be configured with hardware including a CPU, various memories, registers, etc., and software stored in the memory. In addition, some or all of the functions of the determination unit 41 based on such software, etc. can also be configured as electronic circuits / electrical circuits including integrated circuits.

[0092] The judgment unit 41 controls the optical sensor unit 10 to obtain the measurement values ​​of the measurement area, stores them in the data storage unit 43, performs calculations in the calculation unit 44 based on the obtained measurement values, judges the wetness state of the measurement point in the judgment unit 45, and outputs information about the judgment result and data such as the measurement values ​​as necessary. The control unit 42 drives the light source 11 according to a predetermined processing procedure to irradiate the measurement target with the irradiation light 21, causes the light receiving element 17 to measure the detection light 23 generated based on the reflected light 22, and controls a series of operations such as the internal operation of the judgment unit 41 based on the obtained measurement data. The irradiation time, number of irradiations, and irradiation intervals of the irradiation light 21 can be freely set by the control unit 42.

[0093] The calculation unit 44 can perform various calculations based on the acquired measurement values ​​and reference data stored in advance in the data storage unit 43 using prestored software or the like, and calculate the wetness rate, the rate of change, and the like. In addition, for example, the determination of the wetness rate by the determination unit 45 can be performed by storing reference data used for determination in the data storage unit 43 and comparing the reference data with actual measurement data (measured data or calculated data).

[0094] The reference data can be prepared, for example, by setting the measurement target area to a state of 100% wetness and a state of 0% wetness before starting measurement (monitoring), measuring the area with the measuring device, and storing the measured values ​​or data calculated from the measured values ​​as reference data for wetness of 100% and 0% in the data storage unit 43. Alternatively, reference data for various environments can be created in advance for the height (depth) of the liquid covering the surface, temperature, humidity, and type of liquid, and stored in the data storage unit 43. It is also possible to store a plurality of types of reference data by dividing the wetness level into stages.

[0095] The judgment results by the judgment unit 45 can be output as multiple types of judgment results by dividing the wetness rate into stages. It is also possible to output the measured value as is. The judgment results and the measurement results are sent to the control unit 42, and are output to various external devices (hereinafter referred to as "external devices") via the control unit 42 according to the purpose. For example, when used for wetness management of concrete, the judgment results are sent to a water sprinkling control device and used as control data for whether or not to sprinkle water.

[0096] Measurements using the optical sensor unit may be made by simply irradiating light for a fixed period of time, or by irradiating a single pulse, but more accurate determinations can be made by irradiating a train of multiple laser pulses as the irradiating light and measuring. Fig. 11 shows an example of a timing chart of light emission pulses from light source 11 in a configuration in which multiple pulse trains are irradiated and judgments are repeated at regular intervals based on the multiple pulse trains. Fig. 11(a) shows the width of the light emission pulse and the time interval between each light emission pulse, (b) shows an example of a pulse train, and (c) shows multiple pulse trains with a longer time axis to easily show the timing of each judgment for each pulse train.

[0097] For example, as shown in Fig. 11(a), the light source 11 is driven by a pulse train consisting of multiple pulses with a low light emission duty ratio (short light emission time and long light emission intervals between each pulse). This causes multiple short pulses of circularly polarized irradiation light 21 to be emitted at regular time intervals. By shortening the light emission pulse waveform and lengthening the generation interval between each pulse, it is possible to reduce the power consumption of the optical sensor unit 10 and the entire device. In addition, by measuring and judging multiple pulses, it is possible to suppress the influence of external noise, etc.

[0098] Irradiation light 21 is irradiated for each pulse, and the reflected light 22 is measured sequentially by PD (photodetector) 17 as detection light 23. The judgment unit 41 stores the measurement values ​​received from the optical sensor unit 10 in a data storage unit 43, performs various calculations as appropriate using a calculation unit 44, and judges the wetness state using a judgment unit 45 based on the calculation results. The calculation unit 44 can calculate the average or total value of multiple pulses in one pulse train, and judge the wetness rate for each pulse train based on the result. This makes it possible to suppress errors due to the influence of noise and fluctuations in the measurement value caused by vibration. In addition, the wetness rate may be judged by summing up the pulse measurement values ​​for each pulse train, or based on the change in the calculation result (total value, average value, etc.) between pulse trains.

[0099] The judgment unit 41 can be configured with hardware consisting of a CPU (or MPU), a memory unit, various interfaces, and a bus line, and various software (such as an OS and a processing procedure program) stored in the memory unit. It can also be configured with a hardware circuit, or can be configured by combining these with firmware.

[0100] Fig. 12 shows a schematic configuration of an embodiment of a wetness determination device using an MPU. The storage unit, processing procedure program, and other software are included in the MPU or are omitted. The wetness determination device 46 mainly comprises an optical sensor unit 47 according to the second embodiment, an MPU that controls the optical sensor unit 47 to perform measurements and determinations, a power supply PS, and a light source driver (LDD) that drives the light source 11. The wetness determination device 46 also includes an amplifier (AMP) that amplifies the output from the optical sensor unit 47, a feedback circuit (APC) for a monitor light receiving element 48, and a temperature sensor 49.

[0101] Since the output characteristics of the laser of the light source 11 are easily changed by factors such as temperature, the monitor light receiving element 48 controls the driving of the driver LDD of the light source 11 by APC (Automatic Power Control) to form a servo loop that keeps the output of the light source constant, thereby ensuring stable driving of the light source 11. The output value of the light source 11 can be set by a volume or the output of a D / A of the MPU.

[0102] In the optical sensor unit 47, the PBS 13 passes one polarized beam and reflects the other polarized beam. In the optical sensor unit 47 of the wetness determination device 46 shown in Fig. 12, the polarized beam not used as the irradiated light 21 is received by a monitor light receiving element 48 and output as an APC, so that the light source 11 is driven and controlled to maintain a constant output stably by an APC servo loop.

[0103] The MPU emits laser pulses from the light source 11 to the LDD (light source driver). In the example of Fig. 12, the MPU generates pulses to drive the light source 11 and outputs them to the driver LDD, but it is also possible to configure it so that a pulse train is generated by dedicated hardware, or to configure it so that a pulse train is generated by combining the MPU and hardware. However, when the pulse generation is controlled by the MPU software, there are advantages in that the light emission period can be freely set, and the light emission drive control pattern can be easily changed by changing the software.

[0104] Reflected light 22 of irradiated light 21 is detected by the photodetector 17 as detection light 23, and the output converted from light to an electrical signal by the photodetector 17 is amplified by an AMP (amplifier) ​​and input to the ADC (analog-to-digital conversion circuit) of the MPU. When there is no water film, the electrical signal output from the photodetector 17 is small, and this output changes depending on the condition of the concrete surface. It is preferable to provide a circuit that adjusts the AMP circuit so that the output when there is no water film is input to the ADC as approximately "0". Specifically, this adjustment is made by creating a mirror or the like that mimics the unevenness of concrete.

[0105] When a film of water covers an uneven surface, it results in specular reflection (almost total reflection). This state can be adjusted by using smooth glass or other objects that mimic a water film to adjust the amplification factor of the AMP so that an output voltage value (above the threshold value) is obtained that determines that a water film is present. The measurement value amplified and adjusted by the AMP in this way is A / D converted by an MPU or other device, and the result (judgment result) or measurement value is output to an external device. For example, in an external device that manages water sprinkling on concrete, the judgment result and measurement value can be used as control data for water sprinkling control management, etc.

[0106] 12, the wetness determination device 46 is connected to an environmental unit in addition to an external device that performs water sprinkling control based on the measurement data and the determination data. The environmental unit is a device that measures various conditions such as temperature, humidity, and surface temperature of the measurement site (environment) measured by the optical sensor unit 47, and can be configured to correct or modify the measurement data and the determination conditions based on the data from the environmental unit.

[0107] For example, it is expected that it will take a long time for the wetness determination device to measure a wide concrete casting surface by autonomous driving. In some places, the water film may already be gone. Therefore, it is possible to more accurately predict the displacement of the water film over the entire measurement target area based on both the measurement values ​​of the optical sensor unit and the measurement data of the environmental unit.

[0108] Fig. 13 is a diagram showing an example of the schematic configuration of a mobile wetness determination device that measures various measurement points while moving. The mobile wetness determination device 50 includes an optical sensor unit 47, a control unit 51, a battery 52, and a moving mechanism 53. The control unit 51 has the functions of the determination unit 41 shown in Fig. 10 and a function of controlling travel and travel route, etc., and the moving mechanism 53 includes a moving cart, a drive source, a drive mechanism (not shown), wheels, etc., and the travel route, travel speed, etc. are controlled based on the control unit 51. The control unit 51 may have an automatic travel program built in, or may be controlled wirelessly by an external device.

[0109] 13 shows an example of the moving mechanism 53 using wheels, but various other moving mechanisms can be used. For example, a moving guide and a driving mechanism may be used for the moving mechanism. As a driving device for the moving mechanism, various conventional technologies such as piston driving using hydraulic pressure or high-pressure air, driving by rotating a spiral shaft, and driving by wires may be used.

[0110] FIG. 14 illustrates an optical sensor block 55 equipped with an optical sensor unit to be mounted on a wetness determination device that performs measurement while moving. FIG. 14(a) shows a front view of the optical sensor block 55, and FIG. 14(b) shows a cross-sectional view along the line AA′ shown in FIG. 14(a). The optical sensor block 55 shown in FIG. 14 includes an optical sensor unit 56 surrounded by a housing made of aluminum or stainless steel material with good thermal conductivity, a heat dissipation block 57 made of a material with high thermal conductivity that covers the outer surface of the housing of the optical sensor unit 56 while being in contact with the housing with low thermal resistance, and an exterior box 58 that further covers the outside. A heat dissipation space 68 for circulating air is provided between the heat dissipation block 57 and the exterior box 58. The exterior box 58 is provided with an intake port 63, an exhaust port 64, and a fan 65, and the air sucked from the intake port 63 is circulated through the heat dissipation space 68 and discharged from the exhaust port 64, thereby circulating and moving the air in the heat dissipation space 68. The intake port 63 and the exhaust port 64 may be arranged in reverse. A power cable and a communication cable are connected via an input / output connector portion 66.

[0111] The measurement environment for monitoring the condition of the concrete surface is expected to be a harsh environment with high humidity, high or low temperatures depending on the outside temperature, and exposure to direct sunlight, etc. Therefore, the optical sensor unit 56 needs to be able to prevent condensation and the effects of temperature and direct sunlight, and to maintain stable measurement operation for a long time, even in a high or low temperature environment with high humidity.

[0112] 14, the optical sensor unit 56 is covered with a heat dissipation block 57 made of a material with high thermal conductivity (e.g., stainless steel or aluminum) so that heat generated inside the optical sensor unit 56, such as the laser light source, is quickly dissipated to a heat dissipation space 68 via the heat dissipation block 57. The heat dissipation space 68 is circulated by a fan to take in and expel outside air, preventing condensation. In addition, since direct sunlight is blocked by the exterior box 58 and the heat dissipation block, the effects of direct sunlight can also be prevented.

[0113] In addition, the reason why the 1 / 4 wavelength plate 14 of the optical sensor unit 56 is arranged at an angle in Fig. 14 is to prevent the emitted light from the laser light source from being reflected and the reflected light from returning to the laser light source. Also, a light buffer space 18 is provided on the right side of the 1 / 4 wavelength plate 14 in Fig. 14. This is provided to function as a light damper, so that the emitted light slightly reflected by the 1 / 4 wavelength plate 14 is sequentially reflected inside the buffer space 18 and absorbed and eliminated.

[0114] Furthermore, when the wetness determination device 50 is moved while performing measurements, the measurement value may vary significantly due to vibrations and other effects caused by unevenness of the measurement target surface (floor surface) and other factors. In order to deal with such physical vibrations and shocks, the optical sensor block 55 is provided with an elastic member (such as a spring) 62 between a base plate 59 on which an exterior box 58 including the optical sensor unit 56 is placed, and a frame plate 60 on which the optical sensor block 55 is attached to the frame of the moving mechanism 53. In this way, it is also effective to suppress direct vibrations caused by vertical movement or horizontal shaking by supporting the optical sensor block 55 with a cushioning member such as an elastic member or a damper (or supporting or suspending it with a spring or the like).

[0115] In the example of Fig. 14, four adjustment screws 61 for moving the base plate 59 up and down are provided as an adjustment mechanism for adjusting the angle so that the irradiation light 21 is irradiated vertically downward. Although the angle can be adjusted by an adjustment mechanism with three support points, it is preferable to use an adjustment mechanism with four support points in this way in order to mitigate the effect of the spring stress acting obliquely due to the lateral centrifugal acceleration when the moving mechanism (cart, etc.) turns. Note that the angle can be adjusted by providing an adjustment mechanism for manual adjustment as shown in Fig. 14, but it may also be configured to irradiate a laser beam near the surface to be measured, automatically measure the perpendicularity based on the reflected light, and automatically adjust if tilt occurs.

[0116] Fig. 15 is a diagram showing a schematic diagram of the detection value and moving average output when measuring while moving the measurement target area. In the example of Fig. 15, a large amount of water on the surface has evaporated, exposing many irregularities on the surface of the measurement target area, and the water film 71 remains only in the area surrounded by multiple islands, and even within the island-like water film 71, there are some areas 73 where the irregularities are exposed. The horizontal arrows crossing the multiple island-like water films 71 indicate the movement direction of the wetness determination device, and the two pulse waveforms at the bottom exemplify the measurement value (detection value) and the moving average output.

[0117] The detection value is an output of almost "0" when there is no water film 71, and where the water film 71 is present, it is expressed as "1" (a wetness rate of 100%). Also, since there is a possibility that measurements cannot be taken at all locations when measuring intermittently while moving, by handling values ​​obtained by moving averages, it becomes easier to create a diagram that reflects the state of the water film over the entire measurement target area and to control watering.

[0118] For example, when performing water sprinkling control, the presence of a water film is defined as 100%, the water film has disappeared when the moving average output is 10% or less, and 50% is defined as the water film is about to disappear, and control can be performed to start sprinkling when it reaches 50%. Also, since drying progresses rapidly when part of the uneven surface begins to be exposed, in order to reduce the risk of drying as much as possible, control can be performed to start sprinkling when the measured value of the wetness rate is 80% to 70%, which is about 20% lower.

[0119] Figure 16(a)-(d) show the measurement values ​​obtained by moving the measuring device for the measurement targets with different water depths on the concrete surface. The measurement values ​​were obtained by irradiating circularly polarized laser light and linearly polarized laser light with a wavelength of 1450 nm, with the height of the irradiation light being 35 mm, the moving speed of the measuring device being about 5 cm / sec, and the measurement interval being 5 sec. In Figure 16(a), water depth = 2.0 mm, (b) is 0.5 mm > water depth >> 0.5 mm, (c) is 0 mm > water depth >> 0.5 mm, and (d) is water depth = 0 mm.

[0120] With linearly polarized laser light, the measured values ​​fluctuated in all cases (a) to (c) where water was present on the concrete surface, including when the concrete surface was covered with water. This is believed to be due to the effect of the water surface shaking caused by the movement of the measuring device, and also because the condition of the concrete under the water changes depending on the location, since linearly polarized laser light enters the water film and is reflected by the concrete surface even when the surface is covered with water. Since the measurement value fluctuates up and down in this manner with linearly polarized laser light, it is difficult to determine whether or not part of the uneven surface is exposed based on the measurement value.

[0121] In contrast, when measuring with circularly polarized laser light, the measurement value is stable at about 2000 mV in (a) and (b) where the surface is covered with water. (c) shows the measurement value at "0 mm < water depth << 0.5 mm", which is a state much shallower than 0.5 mm, and is the water depth (W) where the water film becomes thin and the uneven surface is exposed. In (c), the measurement value changes greatly between areas with a water film and areas without a water film, and when part of the surface is exposed, the measurement value changes greatly depending on whether or not there is a water film.

[0122] When the water depth becomes shallower and becomes 0 mm<water depth<<0.5 mm as shown in Figure 16(c), the measurement value fluctuates between 2000 mV and 1500-1000 mV. This is because the measurement value changes depending on the unevenness, and it can be understood that the measurement value at the location where interface 72 exists is 2000 mV, and the measurement value at the location where the unevenness of the concrete surface is exposed is 1500 mV-1000 mV.

[0123] As can be seen from Figure 16(c), when the measured value is below 1500mV, it can be determined that the wetness state is changing and is in a transitional state. Also, in (c), the measured value changes significantly between areas with and without a water film, and when part of the surface is exposed, the measured value changes significantly depending on whether or not a water film is present. Therefore, in practical applications, when measuring while moving, it is possible to collect partial average or moving average data and make a judgment.

[0124] Measurements were also taken at depths of 1.5 mm and 1 mm, but as the measurement results were almost the same as those in (a) and (b), they are omitted. In addition, an experiment was also carried out in which the height of the irradiation position (irradiation distance, optical path length) was set to 50 mm, and measurements were taken under the same conditions as in Figure 16 for other points, and the measurement values ​​at a wetness value of 100% were almost the same as those in Figure 16. The measurement values ​​at a wetness value of 0% became lower as the measurement distance became longer.

[0125] In the above description of the optical sensor unit, the measurement for detecting a transitional change in the wetness state has been mainly described as an example. However, as described above, the optical sensor unit of the present invention can also be used for other purposes. For example, it is possible to measure the degree of surface roughness of the measurement object, or to measure the presence or absence of a change in surface roughness when the surface roughness changes.

[0126] It is also possible to measure the surface roughness without using water or other liquid. In this case, for example, a circularly polarized parallel light is irradiated perpendicularly to a reference roughness plane having various levels of standard roughness, and the measured value is stored as a reference value, and the surface roughness can be measured by comparing the measured value of the measurement target with the stored reference value. However, if it is permissible to cover the measurement target surface with water or other liquid, more accurate roughness measurement is possible by supplying water or other liquid to the surface of the measurement target portion so as to cover the entire unevenness of the surface, and then measuring the process of gradually evaporating and drying the liquid to expose the uneven surface.

[0127] The surface roughness may change due to, for example, friction, aging, etc. When measuring whether or not there is such a change in surface roughness, it is also possible to store and measure reference values ​​of various levels in advance, as in the case of measuring surface roughness. However, even if the reference values ​​of various levels are not measured and stored in advance, it is also possible to determine that the surface roughness has changed when the amount of change from the measured value at the initial stage exceeds a predetermined threshold value. [Explanation of symbols]

[0128] 10, 47 56 Optical sensor unit 11 Light source 12 Collimating lens 13 PBS 14 1 / 4 wave plate 15 Opening (light emitting opening or light receiving opening) 16 Condenser lens 17 Photodetector (PD) 21 Irradiation Light 22 Reflected light 23 Detection light 25 Optical system 25a Irradiation optical system 25b Light receiving optical system 40, 50, Wetness determination device 41 Judgment Unit 51 Control Unit 52 Battery 53 Moving mechanism 55 Optical sensor block

Claims

1. An optical sensor unit comprising a light source that emits laser light in the near-infrared wavelength region, an optical system that irradiates the surface having irregularities to be measured with polarized irradiation light from the light source, and a light-receiving element that receives the reflected light from the optical system and outputs an electrical signal corresponding to the amount of reflected light received, wherein the optical sensor unit measures a rapid change in the wetness state of a liquid covering the surface based on the amount of reflected light received, The optical system described above is A collimating lens that makes the laser beam emitted from the light source into parallel light, A beam splitter that allows either the P-polarized component or the S-polarized component of the laser light emitted from the light source to pass through and reflects the other polarization, A quarter-wave plate is provided downstream of the beam splitter and emits the laser light that has passed through the beam splitter as irradiated light with a phase difference of 1 / 4λ, A focusing lens collects the reflected light from the measurement target location, which has passed through the quarter-wave plate and been input to the beam splitter from the opposite direction to the light source, and which has been split by the beam splitter, as detection light. A light-receiving element that receives the detection light focused by the light-gathering lens and outputs a measured value corresponding to the amount of light received, It is equipped with, An optical sensor unit characterized by polarizing the laser light that has passed through the beam splitter into circularly polarized laser light using the quarter-wave plate, irradiating the circularly polarized laser light perpendicularly toward the interface between the air and the liquid in the area to be measured, and outputting the measured value of the detected light as a measurement signal for detecting a change in the wetness state of the interface.

2. The optical sensor unit according to claim 1, characterized in that the irradiated light has a wavelength that is highly absorbed by the liquid.

3. The optical sensor unit according to claim 2, characterized in that the light-receiving element is positioned at a location away from the focal point of the condensing lens that collects the detected light.

4. The optical sensor unit according to claim 3, characterized in that the irradiating light is a laser light in the form of a pulse train with a low emission duty cycle.

5. An optical sensor unit according to any one of claims 1 to 4, which irradiates the light onto a measurement target having an uneven surface and outputs a measurement value, A control unit that controls the optical sensor unit and acquires the measured value of the surface of the object to be measured, A determination unit that determines the wetness of the surface of the object to be measured based on a predetermined reference value that is stored in advance, and outputs the determination result, A wetness determination device characterized by comprising the following features.

6. The wetness determination device according to claim 5, characterized in that the determination unit makes a determination by comparing the rate of change calculated from the measured value with predetermined reference data stored in advance.

7. The wetness determination device according to claim 5, characterized in that the determination unit outputs the warning signal when the measured value is within a predetermined range.

8. The wetness determination device according to claim 7, characterized in that the determination unit has a plurality of predetermined ranges and outputs a different warning signal for each of the predetermined ranges.

9. The wetness determination device according to claim 5, characterized in that the determination unit outputs the warning signal when the measured value drops by 20% or more from the measured value when the entire surface of the object to be measured is covered with liquid.

10. The determination unit comprises a calculation unit that calculates a change value of the wet state based on the change and / or rate of change of a plurality of measured values ​​measured at predetermined time intervals, and a wet state determination device according to claim 5, which determines the wet state based on the change value calculated by the calculation unit and outputs the warning signal.

11. The device includes a moving mechanism for moving the aforementioned wetness determination device. The control unit controls the movement mechanism and the optical sensor unit to move the wetness determination device within a predetermined measurement target area and measure the wetness state at multiple measurement positions within the measurement target area. The wetness determination device according to claim 5, characterized in that the determination unit determines the wetness state of the measurement area based on the measured values ​​at a plurality of measurement positions.

12. The wetness determination device according to claim 11, characterized in that the determination unit makes a determination by comparing the rate of change calculated from the measured value with predetermined reference data stored in advance at one or more of the measurement positions.

13. The wetness determination device according to claim 11, characterized in that the determination unit outputs the warning signal when the measured value at one or more of the measurement positions is within a predetermined range.

14. The wetness determination device according to claim 11, characterized in that the determination unit outputs different warning signals for each predetermined range of multiple measured values ​​at one or more of the measurement positions.

15. The determination unit comprises a calculation unit that calculates a change value of the wet state based on the change and / or rate of change of a plurality of measured values ​​measured at any one or a plurality of the measurement positions at predetermined time intervals, and a wetness determination device according to claim 11, characterized in that it determines the wetness of the entire measurement area based on the change value calculated by the calculation unit and outputs the warning signal.

16. A method for measuring the wetness of a liquid covering the surface of a measurement target having an uneven surface, comprising irradiating a laser beam with a wavelength in the near-infrared region onto the target and measuring the wetness of the liquid covering the surface of the measurement target using the reflected light, An irradiation step in which a laser beam consisting of circularly polarized parallel light with near-infrared wavelength is irradiated at an angle perpendicular to the interface between the air and the liquid in the area to be measured, A light receiving step in which the reflected light from the interface of the irradiated light is received through a light receiving aperture that is concentric with the irradiation aperture of the irradiated light, A branching step in which the reflected light received through the light-receiving aperture is branched as detected light, A measurement step comprising: collecting the branched detection light with a focusing lens, receiving it with a light-receiving element for measurement, and outputting it as a measured value that detects the change in the wet state; A method for measuring a wet state, characterized by comprising the following features.

17. The method for measuring a wet state according to claim 16, characterized in that, in the measurement step, the collected measurement reflected light is received by the light-receiving element positioned away from the focal point of the condensing lens, and an electrical signal corresponding to the amount of light received is output.

18. The method for measuring the wet state according to claim 17, characterized in that, in the irradiation step, light with a wavelength that has a high absorption rate in the liquid is irradiated as the irradiation light.

19. The method for measuring a wet state according to claim 16, characterized in that the liquid is water.

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