KR100572370B1 - Low turbidity turbidity measuring device and its measuring method - Google Patents

Abstract

The present invention relates to a low turbidity turbidity measuring device and a measuring method thereof capable of precisely measuring turbidity by simultaneously measuring the light quantity of a light source and the intensity of scattered light at two points, and including a first optical part 112 installed at an upper portion thereof, and A measurement cell (C) consisting of a second optical unit (113) installed on the side, and a third optical unit (114) spaced apart from the second optical unit by a predetermined distance (L); A light source generator 100 generating a light source to scan a laser beam to the first optical part 112 of the measurement cell C; A light adjusting unit (A) including a light source lens (101) through which the light source generated from the light source generating unit (100) passes, and a half mirror (102); The first light receiving element 103 for detecting the intensity of the light source passing through the half mirror 102 of the light source adjusting unit A, and the laser beam scanned through the first optical unit 112 are formed in the water of the measuring cell. A light receiving unit including a second light receiving element 109 and a third light receiving element 110 installed in the second optical unit 113 and the third optical unit 114, respectively, to detect the intensity of light scattered by the suspended material ( B) and; Standard solution and sample water supply unit (D) is connected to each other through the three-way valve 107 is the standard solution supply unit 300 for supplying the standard solution to the measurement cell (C) and the sample water supply unit 400 for supplying the sample water ; A signal processor 200 which amplifies and digitizes the transmitted light detected by the first light receiving element 103 and the amount of scattered light detected by the second light receiving element 109 and the third light receiving element 110; It characterized in that it comprises a microprocessor 120 for calculating the turbidity value by straightening and correcting the data input from the signal processing unit 200. As a result, by employing two light receiving sensor methods, the intensity of the scattered light is measured, and then the ratio of scattered light is calculated and converted into a turbidity value, thereby obtaining exponentially twice the measurement sensitivity compared to the conventional method.

Turbidity, laser beam, light receiving element, light source, number of samples, standard solution, scattering, transmission, signal processing

Description

Low turbidity turbidity measuring device and measuring method {TUBIDITY MEASURING DEVICE AND ITS MEASURING METHOD}

1 is a block diagram of turbidity measurement of a conventional surface scattered light method

2 is a block diagram of turbidity measurement of a conventional 90-degree scattered light method

3 is a block diagram of turbidity measurement of a conventional raceway metric system

Figure 4a is an overall configuration diagram of a low turbidity turbidity measuring apparatus according to an embodiment of the present invention

Figure 4b is a view from above of the rotating disc of the low turbidity turbidity measuring apparatus according to an embodiment of the present invention

5 is a detailed configuration diagram of the light source generator 100 according to an embodiment of the present invention.

6 is a detailed block diagram of the signal processing unit 200 according to an embodiment of the present invention.

7 is a detailed configuration diagram of signal control performed by the microprocessor 120 according to an embodiment of the present invention.

8 is a detailed configuration of the standard solution and the sample water supply unit (D) according to an embodiment of the present invention

9 is a detailed configuration diagram of the cleaning device 500 according to an embodiment of the present invention

10A and 10B are flowcharts of processing performed by the microprocessor 120 according to an embodiment of the present invention.

11 is a conceptual diagram showing scattering and transmission of light according to a conventional scheme

12 is a conceptual diagram of scattered light measurement using two light receiving sensors according to an embodiment of the present invention;

13 is a cross-sectional view of a bubble trap according to an embodiment of the present invention

14 is a configuration diagram showing another embodiment of the light source generator and the first light receiving device according to the present invention;

<Description of Symbols for Main Parts of Drawings>

A: light adjusting unit B: light receiving unit

C: Measuring cell D: Standard liquid and sample water supply

100: light source generator 101: lens

102: half mirror 103: first light receiving element

104: rotating disk 105: hole position detection sensor

109: second light receiving element 110: third light receiving element

111: drain 112: first optical part

113: second optical unit 114: third optical unit

115: reflected light blocking ring 116: reflector

117: light absorber 120: microprocessor

200: signal processing unit 300: standard liquid supply unit

400: sample water supply unit 500: cleaning device unit

The present invention relates to a low turbidity turbidity measuring device and a measuring method thereof capable of precisely measuring turbidity by simultaneously measuring the light quantity of a light source and the intensity of scattered light at two points.

In general, turbidimeters currently used in water purification plants or water treatment sites mainly use the surface scattering light method as shown in FIG. 1, and the operation principle is to drive the sampling pump 4 to flow the sample water 5 little by little into the measuring wear 3. When light is emitted from the light source 1 onto the surface of the sample water of the measurement wear, the light scattering light of the suspended material contained in the water is detected by the light receiving element 2 and amplified by the amplifying unit 6 to thereby turbidity. Calculation method. Since the intensity of the light received by the light receiving element 2 is increased in proportion to the suspended matter contained in the water, the output signal of the light receiving element 2 is amplified by the analogue unit or digital method using a microprocessor in the amplification unit 6. The signal is processed and converted into turbidity for display.

2 is a 90-degree scattered light method to scan the light in the water by the light source 10 while supplying the sample water 15 to the measurement pump 13 to the measuring wear 13 and a 90 degree perpendicular to the light source 10 or 45 The light receiving element 11 is installed in the direction of FIG. To detect light scattered by the suspended substance, and then amplify the light by the amplifying unit 12 to convert the signal into turbidity by performing an analog or digital signal processing.

The light sources 1 and 10 used in the surface scattered light method (FIG. 1) and the 90-degree scattered light method (FIG. 2) mainly use tungsten lamps, and recently, a method using a laser diode is also used.

FIG. 3 scans the water into the light source 20 with light while supplying the sample water to the measuring cell 21 with a sampling pump in a rayometric method, and installs a light receiving element 22 opposite to detect the intensity of transmitted light. do. At this time, the intensity of the light source is transmitted to the light receiving element 22 by using the half mirrors 24 and 27 and the reflecting mirrors 25 and 26 having the characteristic of reflecting and transmitting light at a constant ratio. ) To amplify and calculate the intensity of the transmitted light and the intensity of the light source proportionally to detect the turbidity.

As described above, the surface scattered light method, the 90-degree scattered light method, or the rayometric method are formed to some extent at high turbidity, but the scattered light is very small at low turbidity, which makes it difficult to accurately measure the scattered light. Therefore, there is no device capable of accurately measuring turbidity even in low turbidity as well as high turbidity.

Accordingly, the present invention is to improve the above problems of the conventional turbidity measurement method, in order to use in water treatment sites, such as water purification plant or sewage treatment plant to measure the light intensity of the light source and the intensity of the scattered light at two points at the same time and turbidity ratio It is an object of the present invention to provide a low turbidity turbidity measuring device and a method for precisely measuring the density thereof.

Low turbidity turbidity measuring apparatus according to the present invention for achieving the above object is a first optical unit 112 installed on the upper side, and a second optical unit 113 installed on the side, a predetermined distance from the second optical unit 113 (L) A light source for generating a light source for scanning a laser beam to the measuring cell (C) consisting of a third optical unit 114 spaced below and the first optical unit 112 of the measuring cell (C) A light adjusting unit (A) comprising a generating unit (100), a light source lens (101) through which the light source generated from the light source generating unit (100) passes, and a half mirror (102); The first light receiving element 103 for detecting the intensity of the light source passing through the half mirror 102 of the light adjusting unit A, and the laser beam scanned through the first optical unit 112 are formed in the water of the measuring cell. A light receiving unit including a second light receiving element 109 and a third light receiving element 110 installed in the second optical unit 113 and the third optical unit 114, respectively, to detect the intensity of light scattered by the suspended material ( B) and; A sample water supply unit 400 for supplying sample water to the measurement cell C; A signal processor 200 which amplifies and digitizes the transmitted light detected by the first light receiving element 103 and the amount of scattered light detected by the second light receiving element 109 and the third light receiving element 110; It characterized in that it comprises a microprocessor 120 for calculating the turbidity value by straightening and correcting the data input from the signal processing unit 200.

Another feature of the present invention is that the sample water supply unit 400 is connected to each other via a three-way valve 107, the standard liquid supply unit 300 for supplying a standard solution to the measuring cell (C).

Another feature of the invention is the rotation disk 104 formed between the half mirror 102 and the first optical portion 112 in the circumferential direction with holes 104a formed at equal intervals to control the blocking and passage of the laser beam. A drive motor 106 and a hole position detection sensor 105 for transmitting a driving force to the rotating disk 104 are included.

Another feature of the present invention is that it includes a cleaning device 500 for cleaning the optical parts 112, 113, 114 attached to the measurement cell (C).

Another feature of the present invention is that a bubble trap is provided on the sample water inlet side of the measuring cell C to remove bubbles or bubbles contained in the sample water.

Another feature of the present invention is to reflect the bottom of the measuring cell (C) in the strong laser light scanned in the measuring cell (C) and then scattered to prevent the phenomenon of entering the light receiving element at the bottom of the measuring cell (C) The reflector 116 is installed obliquely, and the light absorbing material 117 for absorbing light is provided at the end of the reflector 116, and the reflection light blocking ring 115 is provided below the second and third light receiving elements. It is in doing it.

In addition, a low turbidity turbidity measuring apparatus according to the present invention for achieving the above object is a first optical unit 112 installed on the upper side, and a second optical unit 113 installed on the side, from the second optical unit 113 is constant The intensity of the light source is measured in order to scan the laser beam to the measuring cell C comprising the third optical part 114 spaced below the distance L and the first optical part 112 of the measuring cell C. A light source generator 100c having a first light receiving element 103c to detect the light source and generating a light source; A light source lens 101c through which the light source generated from the light source generator 100c passes; The laser beams scanned through the first optical unit 112 are respectively provided to the second optical unit 113 and the third optical unit 114 to detect the intensity of light scattered by the suspended solids in the water of the measuring cell. A light receiving unit B including a second light receiving element 109 and a third light receiving element 110 installed; A sample water supply unit 400 for supplying sample water to the measurement cell C; A signal processor 200 which amplifies and digitizes the incident light detected by the first light receiving element 103c and the amount of scattered light detected by the second light receiving element 109 and the third light receiving element 110; It characterized in that it comprises a microprocessor 120 for calculating the turbidity value by straightening and correcting the data input from the signal processing unit 200.

In addition, a low turbidity turbidity measuring method according to the present invention for achieving the above object is a first optical unit installed on one surface, and a second optical unit installed on the other side in a direction perpendicular to the first optical unit, the second optical In the measuring cell (C) consisting of a third optical unit spaced from a predetermined distance from the unit, scanning the laser beam in the water through the first optical unit provided on one surface of the measuring cell, the light scattered by the suspended solids in the water Detecting the amount of scattered light from each of the light receiving elements provided at the rear end of the second optical unit and the third optical unit on the other side of the measuring cell, and calculating the scattered light detection values of the two light receiving elements as a ratio It is characterized in that it comprises a step of calculating.

Still another feature of the present invention is to detect the amount of scattered light from each of the two light receiving elements, and convert the result into a digital value to straighten and correct it.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 4a-4b is an overall configuration of a low turbidity turbidity measuring apparatus according to an embodiment of the present invention.

As shown in FIG. 4A, the turbidity measuring device according to the present invention includes a first optical part 112 provided at an upper portion thereof, a second optical part 113 provided at a side surface thereof, and a predetermined distance (from the second optical part 113). L) the measuring cell (C) consisting of a third optical unit 114 spaced apart below; A light source generator 100 generating a light source to scan a laser beam to the first optical part 112 of the measurement cell C; Rotating disc formed in the circumferential direction with holes 104a at equal intervals in order to control the blocking and passing of the light source lens 101, the half mirror 102, and the laser beam through which the light source generated from the light source generating unit 100 passes. (104) and a drive motor (106) for transmitting a driving force to the rotating disc (104), and a hole position detecting sensor (105); The first light receiving element 103 for detecting the intensity of the light source passing through the half mirror 102 and the laser beam scanned through the first optical unit 112 are scattered by the floating material in the water of the measuring cell. A second light receiving element 109 and a third light receiving element 110 are respectively installed in the second optical part 113 and the third optical part 114 to detect light intensity; A standard liquid supply unit 300 for supplying a standard solution to the measurement cell C and a sample water supply unit 400 for supplying sample water are connected to each other through a three-way valve 107; A signal processor 200 which amplifies and digitizes the transmitted light detected by the first light receiving element 103 and the amount of scattered light detected by the second light receiving element 109 and the third light receiving element 110; The microprocessor 120 calculates a turbidity value by straightening and correcting the data input from the signal processor 200.

In addition, the cleaning device 500 for cleaning the optical parts mounted on the measurement cell (C) as an accessory device, and a drain 111 for discharging the introduced sample water.

The following describes the operation of these components in more detail.

First, the intensity of the output light of the laser light source is proportional to the current supplied to the laser diode. When the laser diode sends a current above the threshold current at which oscillation of the laser beam starts, a stronger laser is proportional to the current flowing. Output

The laser beam generated by the light source generator 100 is converted into parallel light while passing through the lens 101, and then, in the next half mirror 102, a part of the laser beam enters the first light receiving device 103 which detects the intensity of the light source. Some are reflected and reflected at right angles to be scanned into the water via the first optical unit 112.

The beam scanned into the water passes through a light blocking device comprising a rotating disk 104 having a hole 104a, a driving motor 106, and a hole position detecting sensor 105 for detecting a hole position. As the 104 is rotated, the passage and interruption of the laser beam are repeated. This is used to calibrate the light receiving element and the optical system by blocking the light source to measure the dark current (Dark current) of the second, third light receiving element (109, 110). In order to detect the hole position of the rotating disc 104, the hole position detecting sensor 105 is installed to stop the rotating disc at the correct position.

The second optical unit 113 and the third optical unit 114 provided at the front end of the second light receiving element 109 and the third light receiving element 110 may focus on scattered light on the light receiving element. It consists of a filter for passing only the wavelength.

In addition, in order to prevent the phenomenon that the light is reflected on the bottom of the measuring cell C and scattered among the powerful laser light scanned in the measuring cell C, the light enters the light receiving element, A reflector 116 for reflecting to the side and a light absorber 117 for absorbing light are installed at the end thereof to prevent the incident light from being reflected by the light receiving element, and reflected light below the second and third light receiving elements. Install the blocking ring 115.

5 shows a detailed configuration of the light source generator 100 according to an embodiment of the present invention. When the microprocessor 120 sends information on the intensity of the laser beam output to the reference generator 121, the reference generator 121 outputs a corresponding voltage. The voltage signal output from the reference generator 121 and the voltage signal fed back from the light source 100a through the output detector 124 are compared in the signal comparator 122, that is, with the voltage of the reference generator 121. When the voltage of the output detector 124 is lower than the voltage of the reference generator 121 by comparing the voltage output of the output detector 124 that detects the intensity of the light source 100a, the output voltage is increased to increase the output voltage at the current amplifier 123. The current flowing through the light source 100a, that is, the laser diode, is increased to control feedback so that the output of the laser beam 125 reaches a predetermined target value.

In addition, in order to exclude the change of the wavelength and output caused by the temperature change of the laser diode in case of poor use environment, the laser diode is installed on the thermoelectric element (Peltier element) to control the temperature constantly.

6 shows a detailed configuration of the signal processor 200 according to an embodiment of the present invention, and the signal selector 130 includes a first light receiving element 103, a second light receiving element 109, and a third light receiving element ( One of the signals of 110 is selected to form a low pass filter, which is a primary or secondary integrating circuit, in the filter unit 131 to block noise of high frequency components, and the analog signal in the A / D converter 132. After quantizing the signal into a digital signal, the microprocessor 120 reads the value and stores the value in the memory 141 buffer.

7 illustrates a detailed configuration of signal control performed by the microprocessor 120 according to an embodiment of the present invention.

The microprocessor 120 includes parameters for setting the sampling period and the averaging order of the signal, the cleaning period, the present time, the communication speed, the data transmission period, its own ID number, the type of the communication module, and the like. Parameters can be set or modified using the LCD module 145 displaying.

These parameters are stored in the EEPROM of the memory 141, the internal variable values are stored in RAM, and the operating program is stored in the flash ROM (FROM).

The clock and reset circuit 142 is a part for supporting the microprocessor 120 to operate normally, and the power supply 143 supplies the logic power required to operate all the control elements and the power required to drive the actuator.

The power amplifier 144 protects the microprocessor 120 from noise introduced from the outside by using an optical isolation device in order to amplify the power to control the peripheral device, and receives the output signal of the microprocessor 120. The solenoid 503, the pump 306, etc. are controlled.

The communication module 145 supports the fieldbus function to enable communication with the upper level controller. The communication module 145 is equipped with a communication module suitable for site conditions and selects a communication support program suitable for this as a parameter of Lonworks, Modbus, Ethernet, RS-232c, RS-485, wireless, 4 ~ 20mA current output is converted to the host controller. Types of data to be transmitted include the operation status of the device, the calibration start signal and the initialization function performed from the upper level, and the transmission of measured data.

Figure 8 shows a detailed configuration of the standard solution and the sample water supply unit (D) according to an embodiment of the present invention. The sample water 304 to be measured normally is sucked through the filter 305 to the sampling pump 306 and sent to the electric three-way valve 303. If the flow path of the fluid is set in the sample water direction, the sample water 304 ) Is introduced into the measuring cell (C) to perform the measurement.

On the sample water inlet side of the measuring cell (C), a bubble trap shown in FIG. 13 is installed to remove bubbles or bubbles contained in the sample water so that bubbles are removed while the sample water gradually passes therethrough.

The microprocessor 102 drives the stirrer motor 301 installed in the standard liquid storage tank 302 in advance before the calibration cycle time set in the parameter arrives, thereby removing the separation of the standard liquid over a long time. The fluid flow path of the electric three-way valve 303 is rotated toward the standard liquid so that the standard liquid flows into the measuring cell C, and then the device is calibrated.

The output sensitivity value of each light receiving element generated in the calibration operation is stored in the EEPROM of the memory 141 and used as a value to be corrected at the time of measurement.

9 shows a detailed configuration of the cleaning device 500 according to an embodiment of the present invention. In the cleaning, when the time set in the parameter arrives, the washing water 500a is washed with a high-pressure cleaning pump 501 to periodically clean the surface of the light source supplying glass tube and the light receiving signal transmission tube mounted on the measuring cell C. And the washing water is passed through the ultrasonic cleaner 502 for more reliable cleaning, and is formed of a water jet having high pressure and vibration at the same time, thereby increasing the cleaning function. This operation is performed consistently according to the signal output from the power amplifier 144 by the output of the microprocessor 120.

10A and 10B illustrate a flowchart of processing performed by the microprocessor 120 according to an embodiment of the present invention. Where S denotes a step.

First, when the user turns on the operation switch of the turbidity measuring device according to the present invention, in step S1, the peripheral device and internal variables are initialized, and the background processing and interrupt waiting routine for sequentially initializing the keyboard, communication port, etc. are performed. Step S2 is executed.

Next, it is determined whether the 10ms timer interrupt is activated (step S3). If the 10ms timer interrupt is activated, the measured value is read from the first light receiving sensor 103 and stored in the memory corresponding to the first light receiving sensor 103 ( Step S5) In the same manner, steps S6 and S7 which read the values of the second light receiving sensor 109 and the third light receiving sensor 110 and store them in the respective memories are executed in sequence.

If the signal to be measured is changing at a rapid cycle, and it is necessary to read the values of the light receiving sensors at the same time, if each input signal is latched at the same time by the trigger signal using an element that can latch the signals, In the present invention, since the change of the light receiving sensor signal changes very late compared to the speed at which the microprocessor 120 operates, it is not necessary to read the values of the light receiving sensors at the same time. do.

The data values read from each light receiving sensor are linearized by removing the noise with a FIR or IIR digital filter (step S8), using the least-squares method or polynomial regression method, and corrected by the correction values (step S9). After performing step S10 of calculating and storing in the memory, the process returns to the initial step S2 and repeats the steps of step S5 to step S10 until the 10 ms timer interrupt is not activated.

On the other hand, if the 10ms timer interrupt does not operate, it is determined again whether or not the 100ms timer interrupt is activated (step S4), and if the 100ms timer interrupt is activated, step S12 of displaying the turbidity value on the LCD module is executed. On the contrary, if the 100ms timer interrupt does not operate, the process returns to the steps of S2 and S3.

In addition, after performing step S12, it is determined whether the calibration cycle has been reached in succession, and steps S20 and S21 for performing calibration by adding a standard solution are performed.

In addition, if the cleaning cycle reaches the set value sequentially, after performing step S22 and step S23 to perform cleaning, if the end signal of the system is ON, the operation of the measuring device is terminated, and the end signal of the system is OFF. ) Is repeated from the initial step S2.

On the other hand, Figure 14 is a block diagram showing another embodiment of the light source generator and the first light receiving device according to the present invention. Another embodiment of the method of detecting the amount of the laser beam output from the light source generator 100 using the half mirror 102 and the first light receiving element 103 is an interior of the light source generator 100c made of a laser diode. A method of detecting the light amount of the laser beam 125a output by using the first light receiving element 103c included in FIG. 14 is illustrated in FIG. 14.

Hereinafter, the calculation process of the turbidity value using the turbidity measuring device and the measuring method of the present invention will be described in detail.

The calculation of the turbidity value by the conventional turbidity measuring device or method is a method of converting the turbidity value with the magnitude of the signal measured from the light receiving element installed at a certain distance from the light source as shown in FIG. It is difficult and has the disadvantage of being affected by the change of the light source (I _inc ± Δ) as in Equation (3) below.

In the turbidity measuring apparatus and its measuring method of the present invention, two light receiving sensors are installed at a predetermined interval in the direction of light in order to eliminate the above problems with the conventional turbidity measuring method, and the two signals are proportionally installed. The method of calculating turbidity by calculation is presented.

This will be described in more detail as follows.

The intensity of the scattered light (I _sc ) is affected by the amount of incident light (I _inc ) and the particle size (d), the wavelength (λ), the incident angle (θ), the scattering rate (k), and the number of particles (n). To express

으로 표현된다.

It is expressed as

The light attenuation coefficient μ (λ) for any wavelength λ is the sum of the scattering coefficient s (λ) and the absorption coefficient a (λ)

이다.

to be.

As shown in FIG. 11, in the case of the distance l to the light receiving sensor, the transmission amount I _tr in the direction of the scattered light I _sc and the light in the 90 degree direction is

으로 표현된다.

It is expressed as

In the present invention, as shown in FIG. 12, the scattered light is measured from two light receiving sensors installed in the direction of light propagation, wherein the scattered light I _sc1 and I _sc2 are

In this case, substituting Eq. (2) into Eq. (6) (8), the ratio (ε) of scattered light I _sc1 and I _sc2 is

      As a result, the change in the amount of incident light is canceled and the sensitivity of the scattering rate is doubled. As the distance between the light receiving sensors 109 and 110 increases, more precise measurement becomes possible.

Therefore, as shown in equation (10), the ratio (ε) of the scattered light I _sc1 and I _sc2 is calculated to convert the turbidity value. For example, assuming that the sample number is pure, since the scattered light and the absorbed light are absent, the ratio (ε) is The ratio (ε) becomes exponentially smaller as it becomes '1' and the turbidity is gradually increased, and the calculation of turbidity is obtained by multiplying the inverse of the ratio (ε) by the intrinsic constant (k) according to the shape of the measuring cell. Calculate

In the present invention, by using the value of the intensity of the light source through the first light receiving device 103, the intrinsic constant according to the contamination of the optical parts 112, 113, and 114 mounted on the measurement cell C or the change of the surrounding conditions ( k) is corrected.

In particular, since the conventional method uses only one light receiving sensor, there is no element about distance, but the amount of scattered light is measured and converted into a turbidity value, and the turbidity measuring device according to the present invention is generated, compared to an error in the measured value according to the change in incident light quantity. In the measuring method, the scattering rate, that is, the sensitivity of the turbidity value is increased by 2 times compared to the conventional method, and the farther the distance between the two light receiving sensors, that is, the second light receiving element 109 and the third light receiving element 110, is increased. Accurate measurement is possible and the effect of canceling the change of incident light can be obtained, so that accurate measurement of turbidity value is possible.

As described above, in the present invention, a stable light source can be obtained by using a laser diode as a laser beam generating device, and after measuring the intensity of the scattered light by employing two light receiving sensor methods, the ratio of the scattered light is calculated to a turbidity value. In terms of conversion, the measurement sensitivity can be twice as exponentially compared with the conventional method, and the farther the distance between the two light receiving sensors is, the more accurate the measurement can be achieved and the effect of canceling the change in incident light can be obtained. It is possible to measure the value.

Claims (9)

A first optical part 112 provided at an upper part, a second optical part 113 provided at a side surface, and a third optical part spaced apart from the second optical part 113 by a predetermined distance (L) in the direction of light travel Measuring cell (C) consisting of a portion 114, A light source generator 100 generating a light source to scan a laser beam to the first optical part 112 of the measurement cell C; A light adjusting unit (A) including a light source lens (101) through which the light source generated from the light source generating unit (100) passes, and a half mirror (102); The first light receiving element 103 for detecting the intensity of the light source passing through the half mirror 102 of the light adjusting unit A, and the laser beam scanned through the first optical unit 112 are formed in the water of the measuring cell. In order to detect the intensity of light scattered by the suspended solids, the second light receiving element 109 spaced at a predetermined distance along the traveling direction of the light while being installed in the second optical unit 113 and the third optical unit 114, respectively. ) And a third light receiving unit (B) consisting of; A sample water supply unit 400 for supplying sample water to the measurement cell C; A signal processor (200) for amplifying and digitizing the transmitted light detected by the first light receiving element (103) and the scattered light detection values detected by the second light receiving element (109) and the third light receiving element (110); By calculating the turbidity value by straightening and correcting the data input from the signal processor 200, the ratio of the scattered light detection value of the second light receiving element 109 and the scattered light detection value of the third light receiving element 110 is calculated. A turbidity measuring device for low turbidity characterized in that it comprises a microprocessor (120) using the ratio for the calculation of turbidity value. The turbidity measurement for low turbidity according to claim 1, wherein the sample water supply unit 400 is connected to each other through a three-way valve 107, the standard solution supply unit 300 for supplying a standard solution to the measurement cell C. Device. 3. The rotating disc 104 according to claim 2, wherein a hole 104a is formed in the circumferential direction at regular intervals between the half mirror 102 and the first optical portion 112 to control the blocking and passage of the laser beam. Low turbidity measuring device for a turbidity characterized in that it comprises a drive motor 106, a hole position detection sensor 105 for transmitting a driving force to the rotating disk (104). The cleaning device unit 500 according to any one of claims 1 to 3, wherein the cleaning unit 500 for cleaning the optical units 112, 113, and 114 mounted on the measurement cell C is disposed on one side of the measurement cell C. Low turbidity turbidity measuring device characterized in that it is installed. The turbidity for low turbidity according to any one of claims 1 to 3, wherein a bubble trap is provided on the inlet side of the sample water in order to remove bubbles or bubbles contained in the sample water. Measuring device. According to any one of claims 1 to 3, in order to prevent the phenomenon of scattering and entering the light-receiving element after reflecting to the bottom of the measuring cell (C) among the strong laser light scanned in the measuring cell (C) The reflector 116 is provided inclined at the bottom of the cell C, and a light absorbing material 117 is provided at the end of the reflector 116, and the reflected light is provided below the second and third light receiving elements. Turbidity measurement device for low turbidity, characterized in that the blocking ring 115 is installed. The first optical unit 112 installed on the upper side, and the second optical unit 113 installed on the side, from the second optical unit 113 to the third optical unit 114 spaced below a certain distance (L). The measurement cell (C) In order to scan the laser beam in the first optical unit 112 of the measuring cell (C), a first light receiving element (103c) for detecting the intensity of the light source is installed therein to generate a light source; ; A light source lens 101c through which the light source generated from the light source generator 100c passes; The laser beams scanned through the first optical unit 112 are respectively provided to the second optical unit 113 and the third optical unit 114 to detect the intensity of light scattered by the suspended solids in the water of the measuring cell. A light receiving unit B including a second light receiving element 109 and a third light receiving element 110 installed; A sample water supply unit 400 for supplying sample water to the measurement cell C; A signal processor 200 which amplifies and digitizes the incident light detected by the first light receiving element 103c and the amount of scattered light detected by the second light receiving element 109 and the third light receiving element 110; And a microprocessor (120) for calculating a turbidity value by straightening and correcting data input from the signal processor (200). A measurement consisting of a first optical part provided on one surface, a second optical part provided on the other side in a direction perpendicular to the first optical part, and a third optical part provided at a predetermined distance from the second optical part in a direction of light travel In cell C, Scanning a laser beam in water through a first optical unit provided on one surface of the measurement cell, Light scattered by the suspended solids in the water is provided at the second optical part and the third optical part provided on the other side of the measuring cell to detect the amount of scattered light from two light receiving elements spaced a certain distance along the light traveling direction. Steps, And calculating a ratio of scattered light detection values of the two light receiving elements and calculating a turbidity value using the ratio. The method for measuring turbidity for low turbidity according to claim 8, wherein the amount of scattered light is detected by the two light receiving elements, and then converted into digital values for straightening and correction.

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