JP3008850U - Maintenance-free turbidity measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize a turbidity measuring device that can be continuously measured for a long period of time without maintenance, without being affected by the intensity of a light source, changes in detector sensitivity and contamination of optical windows. [Configuration] Two light sources for measuring turbidity, two detectors for simultaneously detecting scattered light, a drive circuit for driving the light source, and a synchronization for separating and demodulating a detection signal in synchronization with a synchronization signal of the drive circuit It consists of a detection circuit, a division circuit that calculates the ratio of synchronous detection output, and a multiplication circuit that multiplies the output of the division circuit to automatically eliminate the effects of light source changes, detector sensitivity changes, and optical window contamination. It is a maintenance-free turbidity measuring device characterized by arranging an optical mechanism.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This utility model relates to a device for measuring turbidity in rivers, dams, lakes and marshes. Especially in general rivers, urban rivers, dams and construction water areas during floods, turbidity changes rapidly in a short time. Therefore, a turbidity measuring device that can measure for a long time without maintenance is required. Moreover, in these waters, the turbidity measuring device itself is easily contaminated, and therefore a turbidity measuring device having an excellent function that does not require cleaning and calibration of the device for each measurement is required.

[0002]

[Prior art]

 Conventional turbidity measurement methods include a transmitted light method that measures the intensity of transmitted light that is absorbed, scattered, and attenuated by turbidity when the light to be measured passes through the measurement sample, and scattered light that measures the scattered light intensity. There is a method, a transmitted / scattered light method that simultaneously measures the transmitted light intensity and the scattered light intensity.

FIG. 4 shows a transmitted light method, FIG. 5 shows a scattered light method, and FIG. 6 shows a transmitted / scattered light method as an optical configuration showing the measurement principle of each method.

In the transmitted light method, reference numeral 35 in FIG. 4 is a sample for measuring turbidity, reference numeral 36 is a cell in which the sample is placed, reference numeral 37 is a light source, and reference numeral 38 is light emitted from the light source, which is made into a parallel light flux by a condenser lens. Measurement light flux, reference numeral 39 is a light source optical window through which the measurement light flux of the light source enters the sample, reference numeral 40 is a light receiving optical window through which the measurement light flux transmitted through the sample passes, and reference numeral 41 is a detector for detecting the light intensity of the transmitted light. is there.

The relationship between the concentration of turbidity and the intensity of transmitted light in the transmitted light system is expressed by the following equation according to Lambert-Beer's law.

[0006]

[Equation 1]

In the above formula, I _O is the light intensity of the light source, I _T is the transmitted light intensity, k is the proportional constant, m is the turbidity concentration, and d is the thickness of the sample to be measured. w ₁ is the transmittance of the light source optical window, w ₂ is the transmittance of the light receiving optical window, s is the sensitivity of the detector, and E is the signal output of the transmitted light intensity. Exp of the equation (-kmd) represents the transmittance of the sample itself to _(I T / I _O).

In the transmitted light method, the signal output is affected by the intensity of the light source, the change in the sensitivity of the detector, and the dirt on the optical window, as is apparent from the above formula. Therefore, it is necessary to clean the optical window and calibrate the instrument after each measurement.

In the scattered light method, reference numeral 42 in FIG. 5 is a sample for measuring turbidity, reference numeral 43 is a cell in which the sample is placed, reference numeral 44 is a light source, and reference numeral 45 is light emitted from the light source, which is parallel light with a condenser lens. A bundle of measurement light beams, reference numeral 46 is a light receiving field of view of the detector, reference numeral 47 is a light source optical window for making the measurement light beam of the light source enter the sample, and reference numeral 48 is a light receiving optical window for receiving scattered light in the light receiving field of the detector, Reference numeral 49 is a detector for detecting the light intensity of the scattered light.

The relationship between the density of turbidity and the scattered light intensity in the scattered light method is expressed by the following equation.

[0011]

[Equation 2]

In the above formula, I _O is the light source light intensity, I _S is the scattered light intensity, k is the proportional constant, m is the turbidity concentration, and d is the thickness of the sample to be measured. w ₁ is the transmittance of the light source optical window, w ₂ is the transmittance of the light receiving optical window, s is the sensitivity of the detector, and E is the signal output of the scattered light intensity. In this formula, 1-exp (-kmd) is the transmittance of 1.0 (100%) minus the transmittance of the thickness d of the sample, and represents the scattering rate of the sample.

In the scattered light method, as is clear from the above equation, the signal output is affected by the change in the light source intensity, the sensitivity of the detector, and the contamination of the optical window as in the transmitted light method. Therefore, the same defect as in the transmitted light method occurs.

In the transmitted / scattered light system, reference numeral 50 in FIG. 6 is a sample for measuring turbidity, reference numeral 51 is a cell in which the sample is placed, reference numeral 52 is a light source, and reference numeral 53 is a condensing lens for emitting light emitted from the light source. Measurement light flux which has been converted into a light flux, reference numeral 54 denotes a light receiving field of view of the scattered light detector, reference numeral 55 denotes a light source optical window for making the measurement light flux of the light source enter the sample, and reference numeral 56 denotes a light receiving optical window of the transmitted light detector and the scattered light detector. Reference numeral 57 is a detector for detecting the light intensity of the transmitted light, and reference numeral 58 is a detector for detecting the light intensity of the scattered light.

The transmitted / scattered light method generally calculates the ratio of a scattered light signal and a transmitted light signal to be detected to measure turbidity. The relationship with the turbidity concentration is expressed by the following equation.

[0016]

[Equation 3]

In the above formula, I _O is the light source intensity, I _T is the transmitted light intensity, I _S is the scattering intensity, k is the proportional constant of transmission and scattering, m is the concentration of turbidity, and d is the thickness of the sample to be measured. is there. w ₁ is the transmittance of the light source optical window, w ₂ is the transmittance of the light receiving optical window, s _T and s _S are the sensitivities of the transmitted light detector and the scattered light detector, and E is the ratio of the scattered light intensity and the transmitted light intensity. Is the calculated turbidity signal output.

As is clear from the above formula, the transmitted / scattered light method is strictly regarded as having a common optical window, but the optical paths of the transmitted light and the scattered light are different from each other. The result is a turbidimeter that is not affected by changes in the intensity of the light source or dirt on the optical window. However, changes in the sensitivity of detectors that receive transmitted light and scattered light cause measurement errors.

[0019]

[Problems to be solved by the device]

 The present invention realizes a turbidity measuring device having an excellent function capable of continuous measurement without maintenance for a long period of time without being affected by changes in light source intensity, changes in detector sensitivity, and dirt on optical windows. The purpose is.

[0020]

[Means for Solving the Problems]

 The present invention includes two light sources that generate a measurement light flux for measuring turbidity, two detectors that simultaneously receive scattered light generated by the turbidity of a sample to be measured, and detect the light intensity, and a light source. Drive circuit that alternately drives two measuring light fluxes and synchronous detection that separates and demodulates the signals from the two detectors for the two measuring light fluxes into the signals from the four light sources in synchronization with the drive signal from the light source It comprises a circuit, a division circuit for calculating the ratio of the coherent detection outputs by the same measurement light flux of the four coherent detection outputs, and a multiplication circuit for multiplying the output of the division circuit of the two measurement light fluxes. The positions of the light-receiving fields of view of the two detectors are different, and the two measuring light beams are configured to pass through the light-receiving fields of view of the two detectors, and the turbidity is obtained from the output of the multiplication circuit. It is a turbidity measuring device.

Further, if necessary, a light flux limiting plate for limiting the forward scattered light of the measurement light flux is provided between the two detectors.

Further, instead of the division circuit and the multiplication circuit, an analog-digital conversion circuit for analog-digital converting the output of the synchronous detection circuit is added, and the computer performs ratio and multiplication operations on the digitally converted data. To be able to.

As the light source, a semiconductor laser or the like that can be electronically driven at high speed is used, and an optical system forms a parallel light beam to form a measurement light beam. The light flux limiting plate has a structure in which a light-shielding plate is provided with a through hole for the measurement light beam having a diameter substantially equal to the diameter of the measurement light beam.

[0024]

[Action]

 The scattered light of one measurement light beam is detected by two detectors at the same time, and the ratio of the obtained signals is calculated to obtain a turbidity function in which the change in the light intensity of the light beam is eliminated. By multiplying the turbidity function of each measurement light flux obtained by two measurement light fluxes, the sensitivity difference of the detector, the change and the transmittance of the optical window, and the turbidity function of the sample in which the change is eliminated can be obtained. Obtainable. As a result, it is possible to measure turbidity that is not affected by changes in the light intensity of the light source, differences in detector sensitivity, changes, and contamination of the optical window, making it possible to continuously measure turbidity without maintenance for a long period of time. It is possible to realize a turbidity measuring device having the above function.

[0025]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show specific examples of an optical mechanism showing the measurement principle of the present invention, and FIG. 1 shows the configuration of the optical mechanism when the sample cell in which the measurement sample is placed is viewed from the side. Represents the configuration of the optical mechanism when the sample cell 2 is viewed from above.

The turbidity measuring device that is used outdoors in the field does not require a sample cell, and a device designed and manufactured to have a waterproof structure is directly immersed in the measurement sample for measurement.

Reference numerals 1 to 12 in FIG. 1 are the same as those in FIG. Reference numeral 1 is a sample for measuring turbidity, reference numeral 2 is a cell in which the sample is placed, reference numerals 3 to 4 are light sources, and reference numerals 5 to 6 are parallel light beams emitted from the light sources 3 and 4 by the condenser lens 11 and the condenser lens 12. Each of the measurement light fluxes made into various light fluxes, reference numerals 7 to 8 are light-receiving fields of view of the detector 17 and the detector 18, which detect scattered light of the measurement light flux 5 and the measurement light flux 6, and reference numerals 9 to 10 are measurement light fluxes of the light source 3. 5 and respective optical windows for the measurement light flux 6 of the light source 4 to enter the sample 1. Reference numerals 11 to 12 denote the respective light beams emitted from the light source 3 and the light source 4 for forming parallel measurement light flux 5 and measurement light flux 6. Condensing lenses, reference numerals 13 to 14 denote respective optical windows for receiving scattered light in the light receiving fields of the detector 17 and the detector 18, and reference numerals 15 to 16 denote scattered light in the light receiving fields of the detector 17 and the detector 18. Each condensing lens for condensing, reference numerals 17 to 18 are detectors for receiving scattered light Reference numeral 19 is a light beam limiting plate.

The symbol d in FIG. 1 is the same as in FIG. The symbol d represents the light beam distance (optical path length) to the central position of the optical window 9 and the light receiving visual field 7 on the measurement light beam 5 line, and the optical path length to the central position of the light flux limiting plate and the light receiving visual field 8. The optical path lengths up to the central position of the optical window 10 and the light receiving visual field 8 on the 6th line and the optical path lengths up to the central position of the light flux limiting plate and the light receiving visual field 7 are all expressed as equal optical path lengths. Further, h in FIG. 1 represents the vertical distances from the optical window 13 and the optical window 14 to the measurement light beam 5 and the measurement light beam 6, and all represent the same distance.

The measurement light beam 5 of the light source 3 and the measurement light beam 6 of the light source 4 are set so that the incident directions thereof face each other and are parallel to each other. The light receiving field 7 of the detector 17 and the light receiving field 8 of the detector 18 form the same field of view by the condenser lens 15 and the condenser lens 16. The center line of the light receiving field 7 and the center line of the light receiving field 8 are set at positions where the distances to the measurement light beam 5 and the measurement light beam 6 are always equal. The measurement light beam 5 enters from the optical window 9 and reaches the transmission center of the light receiving visual field 7 at d, and the distance to the transmission center of the light receiving visual field 8 is 3 d. Similarly, the distance that the measurement light beam 6 enters from the optical window 10 and reaches the transmission center of the light receiving visual field 8 is d, and the distance to reach the transmission center of the light receiving visual field 7 is 3d. The vertical distances from the optical window 13 and the optical window 14 to the measurement light beam 5 and the measurement light beam 6 are all the same distance (h). The light flux limiting plate 19 is used by providing a light shielding plate with two measurement light flux passage holes having substantially the same diameters as the measurement light fluxes 5 and 6. The light flux limiting plate 19 is arranged at the same position from the center of the light receiving field 7 and the center of the light receiving field 8 so that the measurement light beam can pass through without being blocked.

With the configuration of the optical mechanism described above, the measurement light beam 5 passes through the light-receiving field of view 7 and the light-receiving field of view 8 in the same volume of the sample, and similarly, the measurement light beam 6 passes through the light-receiving field of view 8 and the light-receiving field of view 7. The sample volumes are also equal. Further, the thickness of the sample where the scattered light in the light receiving field 7 of the measurement light beam 5 reaches the light receiving optical window 13 is equal to the thickness of the scattered light in the light receiving field 8 of the same light beam reaching the light receiving optical window 14, and the measurement light beam 6 Is also the same. The light flux limiting plate 19 has a function of blocking the forward scattered light generated during the measurement light flux length from the optical window on which the measurement light flux enters to the light flux limiting plate, and first from the optical window on which the measurement light flux enters. It has the function of equalizing the ratio of the forward scattered light intensity to the light receiving field that transmits and the light receiving field that transmits after passing through the light flux limiting plate, but it is not used in a turbidity measuring device that can tolerate errors due to forward scattering.

FIG. 3 shows an electronic circuit configuration of an embodiment of the present invention, and reference numerals 3 to 4 are light sources similar to those in FIGS. Reference numerals 17 to 18 are detectors similar to those in FIGS. 1 and 2. Reference numerals 20 to 21 are drive circuits for the light source 3 and the light source 4, reference numerals 22 to 23 are scattered lights in the light receiving field 7 and the light receiving field 8 by the measurement light beam 5 of the light source 3, and reference numerals 24 to 25 are light sources 4. Each scattered light in the light-receiving visual field 8 and the light-receiving visual field 7 by the measuring luminous flux 6 is denoted by reference numerals 26 to 27, which are signal amplifying circuits of the detectors 17 and 18, respectively, and reference numerals 28 to 29 are when the light source 3 is driven. The synchronous detection circuits for synchronously detecting the scattered light signals of the detectors 17 and 18 with the synchronous signals of the drive circuit 20, reference numerals 30 to 31 are the detectors 17 and 18 when the light source 4 is driven. Each synchronous detection circuit for synchronously detecting the scattered signal of No. 1 by the synchronous signal of the drive circuit 21, reference numeral 32 is a division circuit for calculating and outputting the signal ratio of the synchronous detection circuit 28 and the synchronous detection circuit 29, and reference numeral 33 is a synchronous detection circuit. 31 and synchronous detection circuit 30 A reference numeral 34 is a division circuit for calculating and outputting the signal ratio, and reference numeral 34 is a multiplication circuit for multiplying and outputting the signals of the division circuit 32 and the division circuit 33.

A circuit for time-integrating the detection signal is added to the synchronous detection circuits 28 to 31, and an averaged signal proportional to the scattered light intensity is continuously output.

Further, instead of the division circuits 32 to 33 and the multiplication circuit 34, the signals of the synchronous detection circuits 28 to 31 can be directly analog-digital converted, and the division and multiplication can be digitally calculated and output.

Under the configuration of FIG. 3, the outputs of the synchronous detection circuit, the division circuit and the multiplication circuit are as follows.

Variables f, L, and r in Expressions 4 to 10 shown below are defined as follows.

The thicknesses of the measurement light beams 5 passing through the sample in the light-receiving fields 7 and 8 are equal, and the thickness of this sample is f ₅ . The measurement light flux 6 is also the same, and the thickness of this sample is f ₆ .

The optical path length (2d) between the light receiving field 7 and the light receiving field 8 for the measurement light beam 5 is equal to the optical path length (2d) between the light receiving field 8 and the light receiving field 7 for the measurement light beam 6. Let this optical path length be L.

The thickness of the sample where the scattered light in the light receiving field 7 of the measurement light beam 5 reaches the light receiving optical window 13 is equal to the thickness of the scattered light in the light receiving field 8 of the same light beam reaching the light receiving optical window 14, and The same applies to 6. Let the thickness of this sample be r.

The output of the synchronous detection circuit 28, which outputs the scattered light intensity signal received by the detector 17 when the light source 3 is driven, is represented by the following equation.

[0040]

[Equation 4]

In the above formula, I _O3 is the light emission intensity of the light source 3, I _S7 is the scattered light intensity of the measurement light beam 5 in the light-receiving field 7, k ₁ is the transmission proportional constant, k ₂ is the scattering proportional constant, and m is The turbidity concentration, d ₇ is the thickness of the sample until the measurement light beam 5 reaches the transmission center of the light-receiving visual field 7. f ₅ is the thickness of the sample of the measurement light beam 5 that is transmitted through the light-receiving field 7, r is the thickness of the sample until the scattered light I _S7 reaches the optical window 13, w ₁₃ is the transmittance of the optical window 13, and s ₁₇ Is the sensitivity of the detector 17, and E ₂₈ is the signal output of the synchronous detection circuit 28. In the above formula, the term I _O [exp {−k ₁ md ₇ }] represents the light intensity of the measurement light flux when the measurement light flux 5 reaches the transmissive center of the light-receiving field 7, and [1-exp {-k ₂ mf ₅ }] represents the scattering rate of the measurement light beam at the transmission center. The term [exp {−k ₁ mr}] represents the transmittance of the scattered light I _S7 reaching the optical window 13. The same terms in Expressions 5, 6, and 7 shown below have the same meanings in the respective measurement light fluxes, light-receiving fields of view, optical path lengths, and optical windows.

Similarly, the output of the synchronous detection circuit 29 that outputs the scattered light intensity signal received by the detector 18 when the light source 3 is driven is represented by the following equation.

[0043]

[Equation 5]

In the above formula, I _O3 is the light emission intensity of the light source 3, I _S8 is the scattered light intensity of the measurement light beam 5 in the light receiving field 8, k ₁ is the transmission proportional constant, k ₂ is the scattering proportional constant, and m is The turbidity concentration, d ₇ is the thickness of the sample until the measurement light beam 5 reaches the transmission center of the light-receiving visual field 7. L is the distance (optical path length) from the transmission center of the light-receiving visual field 7 to the transmission center of the light-receiving visual field 8, f ₅ is the thickness of the sample of the measurement light beam 5 that passes through the light-receiving visual field 8, and r is the scattered light I _S8 The thickness of the sample before reaching the window 14, w ₁₄ is the transmittance of the optical window 14, s ₁₈ is the sensitivity of the detector 18, and E ₂₉ is the signal output of the synchronous detection circuit 29.

The output of the synchronous detection circuit 31 that outputs the scattered light intensity signal received by the detector 18 when the light source 4 is driven is expressed by the following equation.

[0046]

[Equation 6]

In the above formula, I _O4 is the light emission intensity of the light source 4, I _S8 is the scattered light intensity of the measurement light beam 6 in the light receiving field 8, k ₁ is the transmission proportional constant, k ₂ is the scattering proportional constant, and m is The turbidity concentration, d ₈ is the thickness of the sample until the measurement light beam 6 reaches the transmission center of the light-receiving visual field 8. f ₆ is the thickness of the sample of the measurement light beam 6 that is transmitted through the light-receiving field 8, r is the thickness of the sample until the scattered light I _S8 reaches the optical window 14, w ₁₄ is the transmittance of the optical window 14, s ₁₈ Is the sensitivity of the detector 18, and E ₃₁ is the signal output of the synchronous detection circuit 31.

Similarly, the output of the synchronous detection circuit 30 that outputs the scattered light intensity signal received by the detector 17 when the light source 4 is driven is expressed by the following equation.

[0049]

[Equation 7]

In the above mathematical formula, I _O4 is the light emission intensity of the light source 3, I _S7 is the scattered light intensity of the measurement light beam 6 in the light receiving field 7, k ₁ and k ₂ are proportional constants, m is the turbidity concentration, and d ₈ the measuring light beam 6 is the thickness of the sample until it reaches the transmission center of the light receiving field 8. L is the distance (optical path length) from the transmission center of the light receiving field 8 to the transmission center of the light receiving field 7, f ₆ is the thickness of the sample of the measurement light beam 6 that passes through the light receiving field 7, and r is the scattered light I _S7 Is the thickness of the sample before reaching the optical window 13, w ₁₃ is the transmittance of the optical window 13, s ₁₇ is the sensitivity of the detector 17, and E ₃₀ is the signal output of the synchronous detection circuit 30.

The ratio of the signals of the synchronous detection circuit 28 and the synchronous detection circuit 29, which is the output of the division circuit 32, is expressed by the following equation.

[0052]

[Equation 8]

In the above calculation process, the fluctuation of the light intensity of the light source and the transmittance of scattered light reaching the optical window are erased. The same effect can be obtained in the calculation process of the following formula 9.

The ratio of the signals of the synchronous detection circuit 31 and the synchronous detection circuit 30, which is the output of the division circuit 33, is expressed by the following equation.

[0055]

[Equation 9]

The multiplication result of the signals of the division circuit 32 and the division circuit 33, which is the output of the multiplier 34, is expressed by the following equation.

[0057]

[Equation 10]

In the above equation, E _O is the turbidity measurement signal output. From the calculation result of Equation 10 which is the output of the turbidity measurement signal, it is expressed only by the reciprocal of the transmittance corresponding to the sample having a thickness twice the optical path length (L) between the centers of the light receiving visual field 7 and the light receiving visual field 8. The function of the concentration of turbidity is obtained. This function does not include all the variables related to the light intensity of the light source, the difference and change in the sensitivity of the detector, and the change in the transmittance of the optical window, which are erased. Therefore, it is possible to obtain a measurement signal of the turbidity concentration (turbidity) that is not affected by the light intensity of the light source, the difference or change in the sensitivity of the detector, and the change in the transmittance of the optical window.

[0059]

[Effect of device]

 Conventional transmitted light, scattered light, and transmitted / scattered light turbidimeters caused measurement errors due to changes in the light source, changes in detector sensitivity, and dirt on the optical window. In particular, since dirt on the optical window causes a large measurement error, the conventional device requires a large-scale cleaning mechanism and a complicated additional device in order to continuously measure the turbidity for a long period of time. As a result, the cost of equipment and facilities for measurement has become extremely expensive.

The turbidity measuring device of the present invention can measure the turbidity which is not affected by the change of radiation intensity of the light source, the change of sensitivity due to the temperature coefficient of the detector, and the contamination of the optical window.

Therefore, the turbidity measuring work by the turbidity measuring device of the present invention enables a simple turbidity measurement without the work of cleaning the optical window and calibrating the instrument each time the measurement is performed. did. Furthermore, in automatic turbidity measurement, a maintenance-free turbidity measuring device that can continuously measure turbidity for a long period of time without the need for complicated mechanical devices for automatically cleaning the optical window. Was able to be manufactured.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the configuration, structure, and system of an optical mechanism of the present invention, showing a sample cell viewed from the side.

FIG. 2 is an explanatory diagram showing the configuration, structure, and system of the optical mechanism of the present invention, showing the sample cell as viewed from above.

FIG. 3 is an explanatory diagram showing a configuration and system of an electronic circuit of the present invention.

FIG. 4 is an explanatory diagram showing a measurement principle of a conventional transmitted light method.

FIG. 5 is an explanatory diagram showing a measurement principle of a conventional scattered light method.

FIG. 6 is an explanatory diagram showing a measurement principle of a conventional transmitted / scattered light method.

[Explanation of symbols]

1 ... sample, 2 ... sample cell, 3
Light source, 4 light source, 5 measurement luminous flux, 6 measurement luminous flux, 7 light receiving field of view
8 ... Receiving field of view, 9 ... Optical window, 10 ...
Optical window, 11 Optical lens, 12
Optical lens, 13 ... optical window, 14 ... optical window, 15 ... condensing lens, 16 ... condensing lens, 17 ... detector, 18 ... detector, 1
9 ... Luminous flux limiting plate, 20 ... Driving circuit, 21
Drive circuit, 22 Scattered light, 23
Scattered light, 24 scattered light, 25 scattered light,
26 ... Amplification circuit 27 ... Amplification circuit,
28: Synchronous detection circuit, 29: Synchronous detection circuit, 3
0 ... Synchronous detection circuit, 31 ... Synchronous detection circuit, 32
∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙
Multiplier circuit, 35, sample, 36, sample cell, 37, light source, 38, light flux for measurement, 39, light source optical window, 40, light receiving optical window, 41, detection Vessel, 42, sample, 43
‥‥‥ Sample cell, 44 ‥‥‥ Light source, 45 ‥‥
Measurement light flux, 46, light-receiving field of view, 47, light source optical window, 48, light receiving optical window, 49, detector, 50, sample, 51, sample cell, 52 Light source, 53, measurement luminous flux,
54 ... Receiving field of view, 55 ... Optical window of light source, 56
Light receiving optical window, 57, detector, 58, detector,

Claims (3)

[Scope of utility model registration request] 1. A measuring luminous flux for measuring turbidity 2
Table light source, two detectors that simultaneously receive scattered light generated by the turbidity of the sample to be measured and that scatters the measurement light beam, and a drive circuit that alternately drives the light sources to create two measurement light beams And a synchronous detection circuit that separates and demodulates the signals of the two detectors for the two measurement light beams into four signals in synchronization with the drive signal of the light source, and two systems using the same measurement light beams of the four synchronous detection outputs. Of the synchronous detection output, and a multiplication circuit that multiplies the output of the division circuit of the two measurement light fluxes. Further, the optical mechanism is A turbidity measuring device in which two measuring light beams are configured to pass through the light-receiving fields of view of the two detectors, and the turbidity is obtained from the output of the multiplication circuit. 2. The turbidity measuring device according to claim 1, wherein a light flux limiting plate for limiting the forward scattered light of the measurement light flux is provided between the two detectors. 3. A utility model in which an analog-to-digital conversion circuit for analog-to-digital converting the output of a synchronous detection circuit is added in place of the division circuit and the multiplication circuit, and the computer performs ratio and multiplication operations on digitally converted data. The turbidity measuring device according to claim 1.