Linear multi-position compensation wide-range turbidity measurement sensor and application thereof

Abstract

The invention provides a linear multi-position compensation large-range turbidity measurement sensor which comprises a solution carrying disc, an LED light source and a linear photodiode array are arranged corresponding to the solution carrying disc, and a collimating lens is arranged between the LED light source and the solution carrying disc; light emitted by the LED light source through the collimating lens is scattered in a solution to be detected and is emitted out through a light hole of the aperture diaphragm; scattered light at each angle is captured by the linear photodiode array, light intensity information is linearly compensated by the linear photodiode array, and the LED light source and the linear photodiode array are electrically connected with the control system. According to the invention, scattered light at each angle is compensated by a linear array, so that the application range of turbidity measurement is greatly increased, the comprehensiveness and the integration of turbidity measurement are realized, the problems of measurement error increase and resolution reduction under large turbidity are solved, the turbidity measurement range and the measurement precision under high turbidity are greatly improved, and the method is suitable for large-scale popularization and application. The method can be widely applied to the field of water turbidity measurement.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of measuring large-range turbidity of water body, and particularly relates to a linear multi-position compensation large-range turbidity measuring sensor and application thereof. BACKGROUND

[0002] Water turbidity as a key indicator for measuring water quality is of great significance for evaluating water environment health status and ensuring drinking water safety. At present, online turbidity measurement technology is mainly based on optical principles, such as 90° scattering method, which is widely used due to its simple operation and cost-effectiveness. However, due to the fact that traditional optical measurement methods are usually only suitable for single turbidity measurement, the measurement error and resolution decrease under high turbidity, which becomes a bottleneck for technical development, and the measurement effect is also not good under low turbidity. SUMMARY

[0003] Therefore, the application aims to overcome the defects in the prior art and provides a linear multi-position compensation large-range turbidity measuring sensor and application thereof, solves the problem of single turbidity measurement range and increased error under high turbidity, and through linear multi-position compensation of a linear photodiode array, the turbidity in a large range can be measured, and the measurement accuracy is significantly improved. Therefore, the application provides a new technical path for large-range measurement and accurate measurement of water turbidity, and can be applied to high turbidity and low turbidity conditions.

[0004] To achieve the above-mentioned purpose, the technical scheme of the application is as follows:

[0005] A linear multi-position compensation large-range turbidity measuring sensor, comprising a solution carrier disc, an LED light source and a linear photodiode array corresponding to the solution carrier disc, and a collimating lens arranged between the LED light source and the solution carrier disc; the LED light source is arranged to emit light into the solution carrier disc through the collimating lens, and the light is scattered in the to-be-measured solution in the solution carrier disc and is emitted out through the light transmission hole of an aperture diaphragm.

[0006] When the light is scattered in the to-be-measured solution, the scattering light intensity of a single scattering particle is:

[0007] I' = I(θ, l, λ, d, m1, m2, … mx);

[0008] In the formula, θ is the scattering angle, l is the scattering optical path, λ is the incident light wavelength, d is the solution particle size, m1, m2, … mx represent other factors that affect the light intensity. n

[0009] The scattering light of each angle emitted through the aperture diaphragm is captured by the linear photodiode array, and after linear compensation of the light intensity information by the linear photodiode array, the comprehensive light intensity information of the current turbidity is:​

[0010]

[0011] In the above formula: I" is the linear compensation of the integrated light intensity; C(I1, I2,..., In) is the linear compensation function of the i-th diode to capture the photocurrent I n i , and the LED light source and the linear photodiode array are electrically connected to the control system.

[0012] Further, the solution tray is a circular plate with a radius of 5 cm.

[0013] Further, the LED light source uses a 10kHZ sinusoidal modulation light.

[0014] Further, the linear photodiode array uses Hamamatsu S11865-256 chips.

[0015] Further, the light transmission hole diameter of the aperture diaphragm is 15 mm.

[0016] Further, the control system uses MC9S08AW16CFGE.

[0017] A method for measuring turbidity using the wide-range turbidity measuring sensor with linear multi-position compensation, comprising the following steps:

[0018] After the photodiode receives the scattered light and generates a photocurrent I i , it is amplified by a transimpedance amplifier and converted into a voltage value to obtain the linearly collected turbidity information, and then further signal compensation is performed.

[0019] The photodiode receives the scattered light and generates a photocurrent I i , which is amplified by a transimpedance amplifier and converted into a voltage value to obtain the linearly collected turbidity information, and then further signal compensation is performed.

[0020] The change curve of the unknown turbidity solution is collected by the sensor, which is respectively curve-fitted with each standard curve, and the fitting coefficients are obtained to determine the linear compensation coefficient.

[0021] After the linear compensation coefficient is determined, the integrated light intensity information is converted to output the turbidity measurement result, and the turbidity measurement result is transmitted from the control system to the PC.

[0022] Further, the standard curve S1, S2, S3 is obtained by:

[0023] Three standard turbidity solutions L1, L2, and L3 are taken for calibration, and the three groups of turbidity information are

[0024]

[0025] In the formula, L1, L2, L3 are light intensity information received by linear photodiode arrays under low turbidity, medium turbidity and high turbidity solutions respectively; A11, A12 …… A1 256 are available turbidity information linearly collected at each position under low turbidity; A21, A22 …… A2 256 are available turbidity information linearly collected at each position under medium turbidity; A31, A32 …… A3 256 are available turbidity information linearly collected at each position under high turbidity;

[0026] According to L1, L2, L3, draw the change curves S1, S2, S3 of received light intensity with diode position under low turbidity, medium turbidity and high turbidity respectively, and determine three turbidity coefficients for each group of data vectors from the established standard solution turbidity;

[0027]

[0028] In the formula, C1, C2, C3 are standard coefficients of low turbidity, medium turbidity and high turbidity solutions respectively, and then the standard curve groups S1, S2, S3 and the standard coefficient groups C1, C2, C3 of low turbidity, medium turbidity and high turbidity calibration solutions are obtained.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] The present application proposes a linear multi-position compensation method to realize turbidity measurement of a solution, so that it is no longer limited to a fixed turbidity range, but can realize turbidity measurement in a large range, based on that the scattered light at each angle is compensated by a linear array, the application range of turbidity measurement is greatly increased, the comprehensiveness and integrity of turbidity measurement are realized, the problems of measurement error increase and resolution decrease under high turbidity are solved, the turbidity measurement range and the measurement precision under high turbidity are greatly improved, and the present application can be widely applied in the field of water turbidity measurement. BRIEF DESCRIPTION OF DRAWINGS

[0031] The drawings constituting a part of the present application are used to provide a further understanding of the present application, the schematic embodiments of the present application and the description thereof are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0032] Figure 1 It is a schematic diagram of a turbidity measurement sensor of the present application;

[0033] Figure 2 It is a schematic diagram of a turbidity measurement process;

[0034] Figure 3 It is a schematic diagram of a linear compensation process.

[0035] Explanation of reference signs:

[0036] 1 - solution carrier; 2 - LED light source; 3 - linear photodiode array; 4 - collimating lens; 5 - incident light; 6 - aperture stop. DETAILED DESCRIPTION

[0037] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0038] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for the purpose of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0039] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0040] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0041] A linear multi-position compensation wide-range turbidity measurement sensor, as shown in Figure 1 The solution carrier 1 is used to place the water body to be measured. The LED light source 2 and the linear photodiode array 3 are provided corresponding to the solution carrier, and the LED light source and the linear photodiode array are electrically connected with the control system, and the control system is electrically connected with the PC. The collimating lens 4 is provided between the LED light source and the solution carrier to ensure the parallelism of the light.

[0042] LED light source collimating lens into the light 5 in the solution to be measured scattering, and through the light aperture 6 of the light-emitting hole, aperture for limiting the light transmission area; each angle scattering light by linear photodiode array capture, light intensity information by linear photodiode array after linear compensation, conversion output turbidity measurement results, and the turbidity measurement results by control system transmission to PC.

[0043] LED light source selection type for L9437, LED and base fixed, produce wavelength of 870 nm near infrared light, and the front end added collimating lens, ensure the parallelism of light. In order to reduce the interference of stray light in the environment, the measurement light source uses 10 kHZ sinusoidal modulation light. Solution load disc for radius 5 cm circular disc, used to place and fix the solution sample, measurement container using high light transmission optical glass processing. When measuring, add the solution to be measured to the container to the level of LED and photodiode.

[0044] Linear photodiode array using Hamamatsu S11865-256 chip, its effective photosensitive area length is 51.2 mm, the number of diodes 256. Photodiode and base fixed, in front of the photodiode array plus two vertical direction diameter of 15 mm aperture to limit the light path. Control system using MC9S08AW16CFGE as the main control MCU, can control the acquisition part and signal processing part, at the same time with pc communication.

[0045] A kind of wide range turbidity measurement sensor for turbidity measurement using the above linear multi-position compensation, as shown in Figure 2 The method comprises the following steps:

[0046] Photodiode receives the photocurrent I i After the transimpedance amplifier AD8641 amplification and conversion into voltage value, so that the output voltage amplification to the range of mcu acquisition.

[0047] Photocurrent transimpedance amplification voltage and received light intensity linearly related, recorded as:

[0048] U i =aI i

[0049] In the formula, a is linear coefficient.

[0050] After that, the signal is demodulated by double lock-in amplifier, recorded as:

[0051] A i =g(U i )

[0052] In the formula, g() is demodulation process; Ai The demodulation result is the available turbidity information. After obtaining the available turbidity information A1, A2,... A n After that, further signal compensation is performed;

[0053] When turbidity measurement is performed using an unknown turbidity solution, first, the unknown turbidity solution change curve S O is acquired by the sensor O , and curve fitting is performed on S i , respectively, with the standard curve groups S1, S2, S3 to obtain fitting coefficients m1, m2, m3, and the standard coefficient C n corresponding to MAX(m1, m2, m3) is taken as the linear compensation coefficient allocated for this measurement (i = 1, 2, or 3);

[0054] After the linear compensation coefficient is determined, the obtained comprehensive light intensity information is converted to output turbidity measurement results, and the turbidity measurement results are transmitted from the control system to the PC.

[0055] As shown in FIG. 1, the standard curve S1, S2, S3 is obtained by: Figure 3

[0056] Low turbidity solution L1, medium turbidity solution L2, and high turbidity solution L3 are taken for calibration, respectively, and the three groups of turbidity information are:

[0057]

[0058] In the formula, L1, L2, and L3 are the light intensity information received by the linear photodiode array under low turbidity, medium turbidity, and high turbidity solutions, respectively;

[0059] According to L1, L2, and L3, the change curves S1, S2, and S3 of the received light intensity with the diode position under low turbidity, medium turbidity, and high turbidity are drawn, respectively, and three groups of turbidity coefficients are determined for each group of data vectors from the established standard solution turbidity.

[0060]

[0061] In the formula, C1, C2, and C3 are the standard coefficients of the low turbidity, medium turbidity, and high turbidity solutions, respectively, and thus the standard curve groups S1, S2, and S3 of the low turbidity, medium turbidity, and high turbidity calibration solutions and the standard coefficient groups C1, C2, and C3 are obtained.

[0062] The LED light source passes through a collimating lens to ensure the parallelism of the incident light, and the light is scattered in the solution to be measured. The scattering light intensity of a single scattering particle can be represented as:

[0063] I′ = I(θ, l, λ, d, m1, m2,... m n )

[0064] In the formula: the content in brackets is the amount that will affect the scattered light intensity; θ is the scattering angle; l is the scattered light path; λ is the wavelength of the incident light; d is the particle size of the solution particles; m1 and m2 represent other factors that will affect the light intensity.

[0065] At different turbidity levels, the light intensity reflected by the liquid varies. Generally, the greater the turbidity, the larger the scattering angle required.

[0066] Afterwards, an aperture stop is added in front of the photodiode array to limit the light transmission area, so that the main light received by the photodiodes at different positions comes from different directions. For each diode element in the photodiode array, it is assumed that the scattered light current injected into it is I i ′, i represents the diode at the i-th position.

[0067] Since the photodiode array is arranged linearly, the diodes at each position capture scattered light at various angles and perform linear compensation. The result of linear compensation of the light intensity information captured by N linear sensors is the comprehensive light intensity information reflecting the current turbidity, that is:

[0068]

[0069] Where: I″ is the integrated light intensity after linear compensation, which is used to output turbidity information after subsequent processing; C(I1, I2, ..., I n ) is the photocurrent captured by the i-th diode I i The linear compensation function and the overall light intensity received at each position are used to determine the current I i The compensation coefficient C i ; F(I) is the comprehensive processing function after multi-position linear compensation.

[0070] Generally, when the turbidity is medium, the light intensity information at the middle angle has a greater weight, and the weights on both sides decrease. It is necessary to appropriately increase the compensation coefficient C of the diode in the middle part. i The compensation coefficients at both ends are reduced. At high turbidity, the turbidity of the light intensity information at large angles is large, and the weight coefficients at the middle and low positions are reduced. Because the light intensity measured at different positions varies, a comprehensive comparison and arrangement of the light intensity received at each position is performed, and the coefficients of each component are reasonably allocated to perform linear compensation, thereby outputting the linearly compensated integrated light intensity I".

[0071] Finally, the comprehensive light intensity information obtained by the compensation process is further converted into the final turbidity information and output to the PC by the control system.

[0072] The linear multi-position compensation method is used for turbidity measurement of the solution, so that the turbidity measurement is not limited to a fixed turbidity range, but can realize wide-range turbidity measurement, the scattered light at each angle is compensated based on a linear array, the application range of the turbidity measurement is greatly increased, the comprehensiveness and integrity of the turbidity measurement are realized, the problems of measurement error increase and resolution reduction under high turbidity are solved, the turbidity measurement range and the measurement precision under high turbidity are greatly improved, and the linear multi-position compensation method can be widely applied to the water turbidity measurement field.

[0073] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A linear multi-position compensated wide-range turbidity measurement sensor, characterized by: The device comprises a solution carrier plate, an LED light source and a linear photodiode array are provided corresponding to the solution carrier plate, and a collimating lens is provided between the LED light source and the solution carrier plate; the LED light source is incident on the solution carrier plate through the collimating lens, and the light is scattered in the solution to be tested in the solution carrier plate and emitted through the light-transmitting hole of the aperture diaphragm; When light is scattered in the solution to be tested, the scattered light intensity of a single scattering particle is: I′=I(θ,l,λ,d,m1,m2,…m n ); In the above formula: θ is the scattering angle; l is the scattering light path; λ is the wavelength of the incident light; d is the particle size of the solution; m1, m2, ... m n Indicates other factors that may affect light intensity; The scattered light at various angles emitted through the aperture diaphragm is captured by the linear photodiode array. After the light intensity information is linearly compensated by the linear photodiode array, the comprehensive light intensity information of the current turbidity is: In the above formula: I″ is the integrated light intensity after linear compensation; C(I1, I2, ..., I n ) is the photocurrent captured by the i-th diode I i The linear compensation function of In addition, the LED light source and the linear photodiode array are both electrically connected to the control system.

2. The linear multi-position compensated wide-range turbidity measurement sensor according to claim 1, characterized in that: The solution carrier plate is a circular plate with a radius of 5 cm.

3. The linear multi-position compensated wide-range turbidity measurement sensor according to claim 1, characterized in that: The LED light source uses 10 kHz sinusoidal modulated light.

4. The linear multi-position compensated wide range turbidity measurement sensor according to claim 1, characterized in that: The linear photodiode array adopts Hamamatsu S11865-256 chip.

5. The linear multi-position compensated wide range turbidity measurement sensor according to claim 1, characterized in that: The diameter of the light-transmitting hole of the aperture stop is 15 mm.

6. The linear multi-position compensated wide range turbidity measurement sensor according to claim 1, characterized in that: The control system adopts MC9S08AW16CFGE.

7. A method for measuring turbidity using the linear multi-position compensated wide-range turbidity measurement sensor according to any one of claims 1 to 6, characterized in that: The steps include: The photodiode generates a photocurrent I when it receives scattered light. i After that, it is amplified by a transimpedance amplifier and converted into a voltage value to obtain the available turbidity information collected linearly at each position, and then further signal compensation is performed; The unknown turbidity solution change curve is collected by the sensor, and the curve is fitted with each standard curve, and the fitting coefficient is obtained to determine the linear compensation coefficient; After the linear compensation coefficient is determined, the turbidity measurement result is converted and output according to the obtained comprehensive light intensity information, and the turbidity measurement result is transmitted from the control system to the PC.

8. The method for measuring turbidity using a wide-range turbidity measurement sensor with linear multi-position compensation according to claim 7, characterized in that: The method for obtaining the standard curves S1, S2, and S3 is: Three standard turbidity solutions, low turbidity solution L1, medium turbidity solution L2, and high turbidity solution L3, were used for calibration respectively; the three sets of turbidity information are Where L1, L2, L3 are the light intensity information received by the linear photodiode array in low turbidity, medium turbidity and high turbidity solutions respectively; A11, A12...A1 256 Available turbidity information collected linearly at each position under low turbidity; A21, A22...A2 256 Available turbidity information collected linearly at each position under medium turbidity; A31, A32...A3 256 The available turbidity information is collected linearly at each location under high turbidity; According to L1, L2, L3, the curves S1, S2, S3 of the received light intensity changing with the diode position under low turbidity, medium turbidity, and high turbidity are respectively proposed, and three sets of turbidity coefficients are determined for each set of data vectors according to the turbidity of the established standard solution; In the formula, C1, C2, and C3 are the standard coefficients of low turbidity, medium turbidity, and high turbidity solutions, respectively. Then, the standard curve groups S1, S2, and S3 and the standard coefficient groups C1, C2, and C3 of low turbidity, medium turbidity, and high turbidity calibration solutions are obtained.

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