CN204439543U - The main component content measuring system of a kind of emulsion - Google Patents

Abstract

The utility model discloses a system for measuring the main component content of an emulsion, which uses a near-infrared LED and a matched photodiode as the input and output signal source of a photoelectric sensor, uses a W-shaped optical fiber as a non-functional sensor, and uses a lifting stage Adjust the distance between the fiber optic probe and the sample, and use a constant temperature device to keep the temperature of the sample constant; the measurement method uses linear regression analysis to process the measurement data, and adds a reference signal to eliminate external influences such as temperature drift on the measurement stability of the system. The measurement system is not only highly integrated and consumes less samples, but also a non-destructive measurement method; the measurement method also realizes the real-time display of the measurement results, which is very suitable for the measurement and analysis of the main component content of emulsions.

Description

A measuring system for main component content of emulsion

technical field

The utility model relates to a system for measuring the main component content of an emulsion and a detection method thereof, belonging to the technical field of liquid component detection.

Background technique

The liquid to be dispersed (dispersed phase) is dispersed in the form of small liquid droplets in another continuous liquid medium (dispersion medium), and this liquid is dispersed in the form of small liquid droplets in another liquid that is immiscible with it The thermodynamically unstable system formed in is called an emulsion. The diameter of the dispersed phase of the emulsion is generally 0.1-10 μm. From the particle diameter range of the emulsion, most emulsions belong to the coarse dispersion system. Typical food emulsions include milk, goat milk, soybean milk and mayonnaise, etc. The content of main components in these emulsions is related to human health; industrial emulsions include natural latex, latex paint, etc. The content of main components in these emulsions is related to Their pros and cons and their prices. Therefore, in order to promote the safety and fairness of the market, it is of great significance to study an effective method for measuring the content of main components in emulsions.

For the measurement of the main components in the emulsion, it is mainly divided into chemical analysis methods and indirect analysis methods. He Haiqing explored the influence of the main factors in measuring the fat concentration of soybean milk powder by acid hydrolysis method through comparative and orthogonal experiments, and the obtained result of the fat concentration of soybean milk powder was better. Li Jincai and others used acid hydrolysis, improved acid hydrolysis and alkaline ethanol extraction to measure the fat content in soybean milk. The results showed that the results obtained by the alkaline ethanol extraction had good precision and high accuracy. . Zhuo Haihua et al. improved the Robse-Gottied method. For the determination of fat in coconut milk, the analysis time is short, the amount of reagents is less, and the analysis results are accurate. However, the above-mentioned chemical analysis methods have disadvantages such as heavy workload, sample contamination, and slow measurement speed. Gustavsson et al. can measure the fat content of milk within 1 second by measuring the thermal conductivity of milk with transient planar power supply technology. Xin et al. measured the fat and protein content in milk simultaneously with a self-designed measurement system using the laser light transmittance ratio. Bogomolov realized the measurement of fat content and protein content by studying the scattering of visible light by fat and protein in milk, and using partial least squares regression modeling. By measuring the dielectric constant of latex at room temperature, Jayanthy establishes a linear relationship between the dry rubber content in the latex and the dielectric constant (real part), and can measure the dry rubber content in the latex. RejiKumar et al proposed to measure the dry rubber content in natural latex with capacitive sensor method. Zhou Cong of the Analysis and Testing Center of the Chinese Academy of Tropical Agricultural Sciences has developed a new thermal radiation pneumatic method to quickly determine the dry rubber content of natural rubber latex. However, these indirect analysis methods also have disadvantages, such as high consumption of reagents, cumbersome sample pretreatment process, etc., so that rapid measurement cannot be achieved.

Optoelectronic technology combines optical technology and electronic technology, which has caused major changes in people's production, life and combat methods. Optoelectronic technology has become the biggest feature of the development of information technology in the 21st century. At present, optoelectronic technology is developing rapidly in the field of optoelectronic materials and devices, detection technology, opto-mechanical integration, optoelectronic microstructure integration, and military fields, and is combined with various high-tech to promote energy development, environmental protection, food production, medical and health. improve.

Utility model content

The purpose of the utility model is to design a high-sensitivity measuring system for the main component content of the emulsion, and provide a method for detecting the main component content using the detection system.

The utility model adopts the following technical solutions for solving the above-mentioned technical problems:

A system for measuring the main component content of an emulsion, including a light guide module, a signal source module, an optical fiber coupling module, and a photodetector, the light guide module is provided with an optical fiber input end, an optical fiber output end, and an optical fiber probe, and the optical fiber coupling module includes Several self-focusing optical fibers are connected to the optical fiber input end, optical fiber output end and optical fiber probe respectively; wherein, the optical fiber output end is connected to the photodetector through the self-focusing optical fiber, and the optical fiber input end is connected to the signal source module through the self-focusing optical fiber.

Wherein, the light guide module is a W-shaped optical fiber, including five ports, two of which are optical fiber output ends, two are optical fiber probes, and one optical fiber input end; the two optical fiber probes have the same structure, and their end faces include An inner layer and an outer layer, the inner layer is used for vertically incident the light entering the optical fiber input end of the light guide module into the liquid, and the outer layer is used for receiving the light reflected by the liquid.

Further, the signal source module adopts a near-infrared LED, and the signal source module is coupled with an optical fiber input end, and the length of the self-focusing optical fiber connected to the optical fiber input end is an odd multiple of L/4, Where α is a constant and n ₀ is the refractive index.

Further, the photosensitive module is a photodetector, and the photodetector matches the signal source module in spectral characteristics.

Further, the system includes two containers for storing the liquid, and also includes a thermostat placed under the containers for maintaining the temperature of the liquid to be prepared.

As a preference, the optical fiber probe is kept vertical to the liquid surface of the emulsion sample to be tested and the distilled water.

As a preference, a tapered shielding ring is connected to the lower end surface of the self-focusing optical fiber connected to the fiber optic probe, and the shielding ring is formed by crimping a hard material with a dark coating on its inner surface.

A method for measuring the main component content of an emulsion. The method provides a signal conversion module, a photocurrent signal preamplification module, a secondary temperature drift removal amplification module, and a signal processing module. The method is characterized in that: the method is implemented according to the following steps:

Step 1, place the container containing the emulsion sample directly under one fiber optic probe, place the container containing distilled water directly under the other fiber optic probe, the signal source module emits light, and irradiates the light guide module through the fiber coupling module, and the light guide module The formed light beam is vertically irradiated on the surface of the emulsion sample to form an optical signal with the information of the emulsion sample;

Step 2, repeat step 1, and finally obtain the photocurrent signal;

Step 3, performing signal amplification and conversion on the photocurrent signal, and amplifying the photocurrent signal by using a two-stage amplifying circuit;

Step 4, configuring several kinds of emulsion samples with known principal component concentrations, marking the digital signal output by the signal converter, and constructing a standard equation that changes with the digital signal according to the change of the principal component content;

Step 5: Measure the main component content of the emulsion sample to be tested, repeat steps 1 to 3, and substitute the output value of the signal converter into the standard equation obtained in step 4 for calculation, and the content of the main component in the measured sample can be displayed in real time.

Further, said step one specifically refers to:

Step 1.1: Using near-infrared LED as the signal source module, the optical signal is coupled into the W-shaped optical fiber through the self-focusing optical fiber, and divided into two paths with the same light intensity to exit from the optical fiber probe;

Step 1.2: The two outgoing lights are converged through the self-focusing optical fiber and irradiated vertically on the surface of the emulsion sample to be tested and the surface of distilled water. After the light of distilled water is reflected by the mirror surface, it carries the information of the light intensity reflected by the mirror surface of the distilled water liquid, and the optical signals after the two reflections are coupled into the W-shaped optical fiber through the self-focusing optical fiber again.

Further, the step three specifically refers to:

Step 3.1: Use two pre-amplification modules to amplify the two photocurrent signals of the emulsion sample and distilled water respectively and convert them into voltage signals;

Step 3.2: The emulsion sample signal and the distilled water signal are differentially amplified by the second-stage temperature-removing amplification module and sent to the signal conversion module.

Further, the step four specifically refers to:

Step 4.1: configure different emulsion samples with known main component concentrations, and follow the measurement steps from step 1 to step 3, for each concentration of emulsion samples, record the output values of the corresponding signal conversion modules in sequence;

Step 4.2: Use BaSO ₄ as the reference whiteboard for the emulsion sample, and then follow the measurement steps from step 1 to step 3 to record the output value of the corresponding signal conversion module;

Step 4.3: Carry out regression analysis on the measurement data, establish a regression equation, and load the standard equation into the data processing flow of the signal processing module.

Compared with the prior art by adopting the above technical scheme, the utility model has the following technical effects:

The utility model proposes a measurement system for the main component content of the emulsion, which uses a W-shaped optical fiber as a non-functional sensor, that is, as a light transmission path, and ensures that the light is vertically injected into the liquid to be measured during measurement, and can quickly and accurately measure the main component in the emulsion. The composition content is high, the adaptability is strong, and the application range is wide.

A shielding ring is added to the probe. The part of the shielding ring protruding from the fiber optic probe is painted black to ensure that it does not affect the reception of scattered light from the sample and at the same time blocks the reflected light from the container wall. It is not disturbed by external conditions and has low cost. , easy to operate and easy to maintain.

When using a photodetector, it should be noted that the selected device must match the spectral characteristics of the signal source, that is, it is necessary to select a photodetector with a good spectral response according to the working band of the signal source. In the utility model, the photoelectric conversion function is a PIN type photodiode with good spectral response.

The measurement system is not only highly integrated, consumes less samples, but also is a non-destructive measurement method. The measurement system also realizes the real-time display of the measurement results, which is very suitable for the measurement and analysis of the main component content of the emulsion, and can realize real-time display.

Based on the principal component content measurement method of the measurement system, the linear regression analysis method is used to process the measurement data, and a reference signal is added to eliminate the external influence on the measurement stability of the system such as temperature drift; the supporting hardware circuit is equipped with a preamplifier The module circuit is used to amplify the micro-current signal, and the second-level de-temperature drift amplifier circuit is designed to reduce the influence of temperature and humidity drift on the system measurement; the obtained signal is digitally filtered, and then the main component content in the emulsion is calculated by the standard equation . The measurement system is not only highly integrated and consumes less samples, but also a non-destructive measurement method; the measurement method also realizes the real-time display of the measurement results, which is very suitable for the measurement and analysis of the main component content of emulsions.

Description of drawings

Fig. 1 is the block diagram of a kind of emulsion main component content measuring system;

Figure 2 is the light propagation path in the self-focusing optical fiber;

Fig. 3 is a structural diagram of a W-shaped optical fiber in a system for measuring the main component content of an emulsion;

Fig. 4 is a schematic diagram of light intensity variation law of a main component content measuring system of an emulsion;

Fig. 5 is a schematic diagram of the shielding ring in the main component content measurement system of an emulsion;

Fig. 6 is a preamplifier circuit diagram in a method for measuring the main component content of an emulsion;

Fig. 7 is a secondary amplification circuit diagram in a method for measuring the main component content of an emulsion;

Fig. 8 is a schematic diagram of a signal processing module hardware circuit in a method for measuring the main component content of an emulsion;

Fig. 9 is a flow chart of processor reading data in a method for measuring the main component content of an emulsion;

Fig. 10 is a flow chart of digital filtering in a method for measuring the main component content of an emulsion;

Fig. 11 is a flow chart of calculating the main component content in a method for measuring the main component content of an emulsion;

Fig. 12 is a kind of embodiment data fitting curve diagram that adopts emulsion main component content measurement system;

Fig. 13 is a kind of embodiment data fitting curve diagram that adopts emulsion main component content measurement system;

Fig. 14 is a data fitting curve diagram of an embodiment using the emulsion main component content measurement system.

in,

101 Near Infrared LED 102 Photodetector 103 Photodetector

104 Self-focusing fiber   105 Self-focusing fiber 106 Self-focusing fiber

107 W type fiber           108 Self-focusing fiber 109 Self-focusing fiber

110 Measuring cup 111 Measuring cup 112 Constant temperature control module

113 Preamplifier circuit 114 Preamplifier circuit 115 Secondary differential amplifier circuit

116 A/D conversion module 117 Processor 118 Digital tube

119 Operational amplifier circuit module 120 Lifting platform 121 Photoelectric sensor module

122 Measuring system main body

301 Optical fiber output port 302 Optical fiber input port 303 Optical fiber input port

304 Fiber output port 305 Fiber probe 306 Fiber probe

307 Initial light exit port 308 Reflected light entrance port 309 Reflected light entrance port

310 Initial light exit port 311 Reflected light exit port 312 Initial light entrance port

313 Reflected light exit port

501 shielding ring 502 shielding ring

800 shift registers.

Detailed ways

The utility model provides an emulsion main component content measurement system and its measurement method. In order to make the purpose, technical scheme and effect of the utility model clearer and clearer, the utility model is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific implementation described here is only used to explain the utility model, and is not intended to limit the utility model.

In order to achieve the purpose of the above-mentioned utility model, the technical solution of the utility model is a main component content measurement system in an emulsion based on a W-type optical fiber sensor, and its corresponding measurement system is composed as shown in Figure 1, specifically including the following modules:

The light guide module 107, the signal source module 101, and the fiber coupling module include five self-focusing optical fibers 104, 105, 106, 108, and 109 and a photosensitive module. The light guide module 107 is provided with an optical fiber input end 312, an optical fiber output end, and an optical fiber probe. The fiber input end 312, the fiber output end and the fiber probe are respectively connected to a self-focusing optical fiber; wherein, the fiber output end is connected to the photosensitive module through the self-focusing fiber, and the fiber input end 312 is connected to the signal source module 101 through the self-focusing fiber.

The signal source module 101 is used for initial signal transmission of the system. The emission signal of the signal source is the key to this system, and it has high requirements for stability. Light-emitting diode (LED) is an incoherent light source with wide spectral lines and relatively large emission angles. It is more suitable for short-distance optical transmission. Widely, LED has the advantages of low working voltage, fast response, small and light, long service life, etc., which meets the requirements of the utility model, so the near-infrared LED is selected as the signal source of the system.

Wherein, the above-mentioned light guide module 107 is a W-shaped optical fiber, including five ports, two of which are optical fiber output ends 313, 311, two are optical fiber probes 306 and 305, and one optical fiber input end 312; two optical fiber probe structures Same, its end face then comprises inner layer and outer layer, and wherein an optical fiber probe 305 is positioned at the emulsion sample to be measured, and its inner layer is used for the light that enters the light guide module 107 optical fiber input ends to be incident on the emulsion sample vertically, and its outer layer is used for Receive the light diffusely reflected by the emulsion sample; another optical fiber probe 306 is located above the distilled water, its inner layer is used to vertically incident the light entering the optical fiber input end of the light guide module to the distilled water, and its outer layer is used to receive the light diffusely reflected by the distilled water.

W-type optical fiber is a new type of optical fiber, which can realize the separation of incident light and reflected light, thereby greatly eliminating the influence of background light and reducing the influence of light source fluctuation and specular reflection. Its structure is shown in Figure 3. Here, the specific operation of the W-type optical fiber will be described.

The input ends 302 and 303 of the light guide module 107 are respectively used as signal input ends of the light guide module, and their common input end faces are 312; 301 and 304 are respectively used as signal output ends of the light guide module, and their output end faces are 311 and 313. The optical fiber probes 305 and 306 have the same structure, and their end faces include two parts, wherein the inner layer part of one optical fiber probe 305 is 310 and the outer layer part is 309, and the inner layer part of the other optical fiber probe 306 is 307 and the outer layer part is 308 The inner layer 310 of the fiber optic probe 305 is used to vertically incident the light entering the input end 302 of the light guide module 107 to the emulsion sample, and the outer layer 309 of the fiber optic probe 305 is used to receive the light diffusely reflected by the emulsion sample. The inner layer 307 of the fiber optic probe 306 is used to vertically incident the light entering the input end 303 of the light guide module 107 onto the surface of the distilled water, and the outer layer 308 of the fiber optic probe 306 is used to receive the light reflected by the distilled water.

The light entering the optical fiber from the outer layer 309 of the optical fiber probe 305 is diffusely reflected by the emulsion sample to be tested, so it must carry the content information of the main component of the emulsion sample. The light entering the optical fiber from the outer layer 308 of the optical fiber probe 306 is light reflected by distilled water, so it carries information about the light intensity reflected by the liquid specular surface. The two detected optical signals are differentially amplified, which eliminates the influence of external factors such as specular reflection and light source fluctuation, and only has diffuse reflection light intensity. Since the diffuse reflection light intensity is closely related to the concentration of the emulsion sample to be tested, i.e. the content of the main component in the sample, according to the difference in the intensity of the reflected light emitted by the output terminals 301 and 304, the emulsion sample to be tested can be obtained. The content percentage of the main component, which is the measurement principle of this system.

The light emitted from the optical fiber output ends 311 and 313 of the light guide module 107, after passing through the coupling optical fiber modules 106 and 104, is incident on the surface of the photodetectors 103 and 102, and the two optical signals are converted by the photodetectors 103 and 102 into an electrical signal. The photodetector is sealed in a dark box to protect it from external light. Detecting the intensity of these two electrical signals is equivalent to detecting the intensity of the light signal, so the electrical signal also reflects the content information of the main components of the emulsion to be tested.

Further, the signal source module adopts a near-infrared LED, and the signal source module is coupled with an optical fiber input end, and the length of the self-focusing optical fiber connected to the optical fiber input end is an odd multiple of L/4, Where α is a constant and n ₀ is the refractive index.

The fiber coupling module 105 is used to couple the initial signal emitted by the signal source module 101 into the light guide module 107; the fiber coupling modules 108 and 109 are used to emit the initial signal to the liquid surface, and couple the light signal reflected by the liquid into In the light guide module 107 ; the fiber coupling modules 104 and 106 are used to send the light signals reflected by the sample to the photodetectors 102 and 103 . The optical fiber coupling method and the optical fiber coupling method used in the present invention are described here.

Since the signal source needs to be coupled with the input end 312 of the optical fiber, the system described in the present invention adopts a self-focusing coupling method, and the light propagation path in the self-focusing optical fiber is shown in FIG. 2 . It can be seen from the figure that light with different incident angles propagates in the self-focusing fiber with the same spatial period Where α is a constant and n ₀ is the refractive index. When the length of the self-focusing fiber is L/4 or an odd multiple of L/4, when the light is emitted from the fiber section, it is emitted along the tangent direction of the sinusoidal curve, that is, emitted in a direction parallel to the axis of the fiber. Therefore, when the length of the selected self-focusing fiber is 1/4 of the period L, high-efficiency coupling of signals can be achieved.

The key to measuring the main component content of the emulsion in this system is to measure the light intensity emitted from the optical fiber output ends 301 and 304 . Therefore, ensuring its stability is the key to getting accurate measurement results.

There are three main factors affecting the intensity stability of the optical signals emitted from the optical fiber output ends 301 and 304 as follows.

First, the stability of the initial light intensity entering the light guide module 107 , that is, the stability of the output of the signal source module 101 . The signal source of this system is near-infrared LED. The power supply we supply to the near-infrared LED is a regulated power supply. After testing, the output light intensity is stable and meets the measurement requirements.

In this embodiment, the photosensitive module is used to receive the optical signal emitted from the W-shaped optical fiber, and convert the optical signal into an electrical signal. The photosensitive module is composed of photodetectors 102 and 103, which are electronic devices that convert measured optical signals into electrical signals. When using a photodetector, it should be noted that the selected device must match the spectral characteristics of the signal source, that is, it is necessary to select a photodetector with a good spectral response according to the working band of the signal source. In the utility model, it is a PIN type photodiode that plays the role of photoelectric conversion.

Second, the distances between the fiber optic probes 305 and 306 and the liquid surface of the emulsion and the liquid surface of distilled water, respectively. The factor affecting the intensity of the light signal emitted from the output end is not only the concentration of the main components of the emulsion sample, but also the distance from the fiber optic probe to the liquid surface. Therefore, only by keeping the distance from the optical fiber probe 305 to the liquid surface of the emulsion sample and the distance from the optical fiber probe 306 to the liquid surface of distilled water equal and constant, can it be ensured that the difference in the intensity of the optical signals emitted by the output terminals 301 and 304 is only the same as the main intensity of the emulsion sample. component concentration.

In the specific measurement, since the initial light emitted by the inner layer of the fiber optic probe is reflected by the liquid surface, it must return from the outer layer. Therefore, it is necessary to ensure vertical incidence, that is, to ensure that the optical fiber probe 305 is kept perpendicular to the liquid surface of the emulsion, and to ensure that the optical fiber probe 306 is kept perpendicular to the liquid surface of distilled water. The probes 305 and 306 of the W-shaped fiber are hung down by the same length from the platform where the system is placed, and they are kept vertical in the subsequent measurements.

Measure the same volume of the emulsion sample to be tested and distilled water, pour them into the measuring cups 111 and 110 respectively, place the measuring cups 111 and 110 on a thermostat 112 at the same time, and then place the entire thermostat 112 on a lift that can be fine-tuned On stage 120. Place the measuring cups 111 and 110 directly below the hanging fiber optic probes 305 and 306 to ensure that the light emitted by the probe 305 can just hit the center of the emulsion liquid surface, and the light emitted by the probe 306 can just hit the center of the distilled water liquid surface central. Then, the distance from the optical fiber probe to the liquid surface can be controlled by adjusting the height of the lifting platform 120 .

Through the above-mentioned a large number of experiments, it is found that when the liquid level of the emulsion sample to be tested approaches the optical fiber probe from far to near by adjusting the height of the lifting platform, the light intensity emitted from the optical fiber output end 301 first increases and then decreases. The changing law of light intensity is shown in Fig. 4.

If the measurement distance is selected too large, the signal will be weak and difficult to distinguish; if the measurement distance is selected too small, small distance changes will cause large errors. At the apex of the curve (x=2.8cm), the slope is the smallest, that is, the change of the distance has the smallest influence on the voltage output. At the same time, the signal strength here is also the largest, so this distance is selected as the best measurement distance. In the process of calibration and measurement, the distance between the probe and the emulsion liquid surface is selected as this value. By measuring a quantitative volume of samples and ensuring that the depth of the shielding ring into the measurement container remains unchanged, the measurement distance can be guaranteed to remain unchanged.

Third, the influence of stray light. The light emitted from the inner layer of the optical fiber probe returns to the optical fiber from the outer layer after being reflected by the liquid surface. Since the probe is exposed, there must be stray light that enters the optical fiber along with the reflected light and is finally received by the detector. Stray light mainly includes external light and light reflected by the cup wall of the liquid container. Since these two kinds of stray light are only related to the external conditions and do not carry any information about the emulsion sample, they must be filtered out.

In order to filter out the stray light mentioned above, a shielding ring as shown in Figure 5 is specially designed. The shielding rings 501 and 502 are identical in structure and shape. They can be made of any hard material, they are circled into a conical shape, and fixed on the fiber optic probe respectively, and the height is properly selected according to the height from the fiber optic probe to the liquid surface. The parts of the shielding rings 501 and 502 protruding from the fiber optic probe have their inner walls painted black to block the reflected light from the container wall while ensuring that the reception of scattered light from the sample is not affected.

After using the shielding rings 501 and 502, due to the vertical incidence, the light emitted from the inner layer 310 of the fiber probe 305 and the light emitted from the inner layer 307 of the fiber probe 306 can still return to the optical fiber from the outer layers 309 and 308 after being reflected by the liquid . Most of the light reflected by the cup wall and the external light cannot enter the optical fiber due to the blocking of the shielding rings 501 and 502 and the absorption of the black inner wall, and the influence on the measurement result has been minimized.

The constant temperature control module 112 is used for temperature compensation of the measurement system. The difference in sample temperature will cause the difference in the absorbance of the sample. In order to ensure the accuracy of the measurement, the sample must be subjected to constant temperature control. The utility model designs a small temperature control system based on a thermoelectric cooler (TEC). When the temperature sensor obtains the real-time temperature of the sample, the PWM wave is adjusted according to the output control value to control the output current of the bipolar driver, and the TEC realizes heating or cooling of the sample. The designed system is small in size and low in cost, which can help the system realize constant temperature measurement under dynamic temperature.

In this embodiment, a liftable stage module 120 is also provided, and the height of the liftable stage can be adjusted to control the distance between the liquid surface of the emulsion and distilled water and the optical fiber probe.

The detection of the main components of the emulsion needs to solve the following three problems: the first is to design a high-precision photoelectric sensing system; the second problem is to design the supporting hardware circuit, the most important of which is to design the photocurrent pre-amplification module circuit to amplify the micro-current signal, and design a secondary de-temperature drift amplifier circuit to reduce the impact of temperature and humidity drift on system measurement; the third is to design a data processing flow to process the signal and perform digital filtering on the obtained signal , and then calculate the main component content in the emulsion by the standard equation.

Using the emulsion main component content measurement system provided by the utility model as a high-precision optical sensing system solves the first problem, and then providing supporting hardware circuits and accurate measurement methods can provide a complete implementation of the emulsion main component content measurement plan.

As an auxiliary hardware circuit, the measurement method disclosed in the utility model also provides the following equipment:

The photocurrent signal preamplification modules 113 and 114 are used to amplify the photocurrent signal and convert the current signal into a voltage signal, which is an important part of the main body of the measurement system. Fig. 6 has provided the preamplifier circuit of the present utility model, and output voltage expression is as follows:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

The secondary de-temperature drift amplification module 115 is used to eliminate component performance drift caused by external environmental factors, and also to re-amplify the voltage signal. A reference signal is added to receive the scattered light signal of distilled water, and other aspects of the design are completely consistent with the measurement branch. The secondary amplifier circuit is shown in Figure 7, _V1 represents the output of the preamplifier circuit of the measurement branch, which is coupled to the non-inverting terminal of the operational amplifier through _R2 and _R4 , and _V2 represents the output reference of the preamplifier circuit of the reference branch signal, coupled to the inverting terminal of the op amp through _R1 .

The signal conversion module 116 is configured to convert the output analog voltage signal into a digital signal.

The signal processing module 117 is used for processing the output data of the A/D converter in the signal conversion module 116 and displaying the data in the display module 118 . It is the core of the main body of the entire measurement system, and it is divided into the hardware part and the data processing flow part.

The data display module 118 is used to display the concentration of the measured sample in real time. The utility model utilizes the processor 117 to realize the LED digital tube display.

The operational amplifier circuit module 119 is used to amplify the electrical signal after photoelectric conversion, and includes preamplifier circuits 113 , 114 and a two-stage differential amplifier circuit 115 . The circuit structures of the preamplifier circuits 113 and 114 are exactly the same. The scattered light is output by the output terminals 301 and 304 of the light guide module 107 and then received by the photodiodes 103 and 102 respectively, and converted into a photocurrent signal. The signal output from the photodetector 103 has information about the content of the sample components, but it is very weak, only at the level of microamperes, so it needs to be amplified by an amplifier circuit, which is the preamplifier circuit. At the same time, in order to eliminate the influence of external environmental factors (temperature, humidity, etc.) Output photocurrent signal with distilled water specular reflection. The pre-amplification output of the reference signal and the output of the pre-amplification circuit with sample information are differentially amplified once to form a secondary amplifying circuit 115 .

In the hardware part, the microcontroller adopts the general-purpose processor AT89C52 in the 8051 series. Figure 8 is a schematic diagram of the connection between microcontroller AT89C52, A/D converter MC14433 and shift register.

Adopt above-mentioned measurement system and hardware equipment, realize the method for measuring the main component content of emulsion, this method is implemented according to the following steps:

Step 1, the signal source module emits light, and irradiates the light guide module through the optical fiber coupling module, and the light beam formed by the light guide module is vertically irradiated onto the surface of the emulsion sample to be tested to form an optical signal with the information of the emulsion sample to be tested;

Step 1.1: Using near-infrared LED as the signal source module, the optical signal is coupled into the W-shaped optical fiber through the self-focusing optical fiber, and divided into two paths with the same light intensity to exit from the optical fiber probe;

Step 1.2: The two outgoing lights are converged through the self-focusing optical fiber and irradiated vertically on the surface of the emulsion sample to be tested and the surface of distilled water. After the light irradiated into the emulsion sample is diffusely scattered by the emulsion, it carries the component content information of the emulsion sample to be tested; After the light irradiated into the distilled water is reflected by the mirror surface, it carries the information of the light intensity reflected by the liquid mirror surface, and the optical signals after the two reflections are coupled into the W-shaped optical fiber through the self-focusing optical fiber again.

Step 2, repeat step 1, and finally obtain the photocurrent signal.

Step 3, performing signal amplification and conversion on the photocurrent signal, and using a two-stage amplifying circuit to amplify the photocurrent signal;

Step 3.1: Use two pre-amplification modules to amplify the two photocurrent signals of the emulsion sample to be tested and the distilled water respectively and convert them into voltage signals;

Step 3.2: Differentially amplify the signal of the emulsion sample to be tested and the signal of distilled water through the second-level temperature-removing amplification module and send it to the signal conversion module.

Step 4, configuring several kinds of emulsion samples with known principal component concentrations, marking the digital signal output by the signal converter, and constructing a standard equation that changes with the digital signal according to the change of the principal component content;

Step 4.1: configure different emulsion samples with known main component concentrations, and follow the measurement steps from step 1 to step 3, for each concentration of emulsion samples, record the output values of the corresponding signal conversion modules in sequence;

Step 4.2: Use BaSO ₄ as the reference whiteboard for the emulsion sample, and then follow the measurement steps from step 1 to step 3 to record the output value of the corresponding signal conversion module;

Step 4.3: Carry out regression analysis on the measurement data, establish a regression equation, and load the standard equation into the data processing flow of the signal processing module.

Step 5: Measure the main component content of the emulsion sample to be tested, repeat steps 1 to 3, and substitute the output value of the signal converter into the standard equation obtained in step 4 for calculation, and the content of the main component in the measured sample can be displayed in real time.

The data processing flow is divided into two parts, one part is that the microprocessor reads the converted data from the A/D converter; the other part is the measurement of the main component content of the emulsion sample to be tested, including the calculation of absorbance conversion and main component content value .

In the first part of the design, the flow of data reading is shown in Figure 9. The digital filtering of the system is a compound filtering based on median filtering and average filtering, and its flow chart is shown in Fig. 10 .

In the second part of the design, it is necessary to configure standard samples of various concentrations in the calibration experiment, and determine the regression equation by performing linear regression analysis on a large amount of data measured by standard samples

y=ax+b (2) This formula is a function of y about x, x represents the diffuse reflection absorbance of the emulsion sample, and y represents the percentage value of the main component of the emulsion sample; the diffuse reflection absorbance x of the emulsion sample is determined by the formula (3) Work out:

Among them, V _reference is the light intensity value obtained by measuring the BaSO4 white board, expressed by the output voltage value, and V _sample is the light intensity value obtained by measuring the emulsion sample, expressed by the output voltage value. Through the measured calibration data, the values of coefficients a and b are obtained, so as to determine the standard equation.

Finally, calculate the principal component content, and the data processing flow is shown in Figure 11: first calculate the absorbance value, and then calculate the principal component of the sample by calling the calibration equation calculation subroutine that has been loaded into the microprocessor percentage content.

For the pre-amplification circuit module of the system, based on the principle of micro-current amplification and high precision, the high-gain ICL 7650 operational amplifier is used to realize the amplification and conversion of weak optical signals.

For the signal conversion module, choose MC14433 three-and-a-half double-integral A/D converter, and choose the general-purpose processor AT89C52 in the 8051 series. When measuring the sample, the light scattered by the sample and distilled water is output from the W-shaped optical fiber output end and received by the photodetector respectively, and then sent to the A/D converter after being amplified by the two-stage amplifier circuit. When the microprocessor inquires that the data conversion signal port INT1 is valid, the microprocessor reads the conversion data of MC14433, after data processing, it is substituted into the standard equation calibrated in advance to calculate the main component content of the emulsion sample, and finally sent to the display module 118 Displays the measurement results.

Example 1

Take the measurement of dry rubber content in natural concentrated latex as an example. Calibration is required before measuring samples of unknown concentration, and can be measured directly afterwards. Configure standard concentration samples, the lowest dry glue content concentration is 15%, the highest dry glue content concentration is 50%, with an interval of 5%, a total of 8 groups of samples. Put the BaSO ₄ whiteboard and these 8 groups of samples under the fiber optic probe 1 in turn, and the distilled water under the fiber optic probe 2, read out the voltage value output by the secondary amplifier circuit module in turn (can be measured with an oscilloscope), and substitute the voltage value into the formula (2) Record the calculated absorbance data in Table 1.

Table 1 Measured Latex Data Sheet

The fitting equation obtained is

y=-128.128x+72.54 (4)

The fitted curve is shown in Figure 12, the abscissa is the absorbance of the natural latex, and the ordinate is the dry rubber percentage of the natural latex.

During concrete measurement, the natural rubber latex sample of unknown dry glue content is put into the system described in the utility model, can directly display its dry glue percentage content on the digital display tube.

Example 2

Take the measurement of fat content in soybean milk as an example. Calibration is required before measuring samples of unknown concentration, and can be measured directly afterwards. Configure standard concentration samples, the lowest fat content concentration is 0.213%, the highest fat content concentration is 1.698%, a total of 8 groups of samples. Put the BaSO ₄ whiteboard and these 8 groups of samples under the fiber optic probe 1 in turn, and the distilled water under the fiber optic probe 2, read out the voltage value output by the secondary amplifier circuit module in turn (can be measured with an oscilloscope), and substitute the voltage value into the formula (2) Record the calculated absorbance data in Table 2.

Table 2 Measuring Soymilk Data Sheet

The fitting equation obtained is

y=-7.176x+2.59 (5)

The fitted curve is shown in Figure 13, the abscissa is the absorbance of the soy milk, and the ordinate is the fat percentage of the soy milk.

During specific measurement, the soybean milk sample with unknown fat content is put into the system described in the utility model, and its fat percentage content can be directly displayed on the digital display tube.

Example 3

Take the measurement of fat content in coconut milk as an example. Calibration is required before measuring samples of unknown concentration, and can be measured directly afterwards. Configure standard concentration samples, the lowest fat content concentration is 0.415%, the highest fat content concentration is 1.168%, a total of 8 groups of samples. Put the BaSO ₄ whiteboard and these 8 groups of samples under the fiber optic probe 1 in turn, and the distilled water under the fiber optic probe 2, read out the voltage value output by the secondary amplifier circuit module in turn (can be measured with an oscilloscope), and substitute the voltage value into the formula (2) Record the calculated absorbance data in Table 3.

Table 3 Measuring Coconut Milk Data Sheet

The fitting equation obtained is

y＝-5.843x+2.439 (6)

The fitted curve is shown in Figure 14, the abscissa is the absorbance of the coconut milk, and the ordinate is the fat percentage of the coconut milk. During concrete measurement, the coconut milk sample of unknown fat content is put into the system described in the utility model, can directly display its fat percentage content on the digital display tube.

It can be understood that those skilled in the art can make equivalent replacements or changes according to the technical solution of the utility model and its utility model concept, and all these changes or replacements should belong to the appended claims of the utility model protected range.

Claims (6)

1. a kind of emulsion main component content measuring system, it is characterized in that: comprise light guide module, signal source module, optical fiber coupling module and photosensitive module, described light guide module is provided with optical fiber input end, optical fiber output end and optical fiber probe, so The optical fiber coupling module includes several self-focusing optical fibers, and the optical fiber input end, the optical fiber output end and the optical fiber probe are respectively connected to the self-focusing optical fiber; wherein, the optical fiber output end is connected to the photosensitive module through the self-focusing optical fiber, and the optical fiber input end is connected through the self-focusing optical fiber Signal source module. 2. A system for measuring the main component content of emulsion according to claim 1, characterized in that: the light guide module is a W-shaped optical fiber, including five ports, and the leftmost and rightmost two of the upper part are optical fiber output The bottom two are fiber optic probes, and the fiber input end in the middle of the upper part; the two fiber optic probes have the same structure, and their end faces include an inner layer and an outer layer. The inner layer is used to vertically Incident into the liquid, the outer layer is used to receive the light reflected by the liquid. 3. A kind of emulsion main component content measuring system according to claim 1, is characterized in that: described signal source module adopts near-infrared LED, and described signal source module is coupled with the optical fiber input end, and the self-connected on the optical fiber input end The length of the focusing fiber is an odd multiple of L/4, Where α is a constant and n ₀ is the refractive index. 4 . The system for measuring the main component content of an emulsion according to claim 3 , wherein the photosensitive module is a photodetector, and the photodetector matches the signal source module in spectral characteristics. 5. The emulsion main component content measuring system according to any one of claims 1 to 4, characterized in that: the system includes two containers for containing liquid, and also includes a thermostat, and the thermostat is placed in the container Below, it is used to maintain the temperature of the liquid to be prepared. 6. A kind of emulsion main component content measuring system according to claim 5, it is characterized in that: the lower end face of the self-focusing optical fiber connected on the said optical fiber probe is provided with a tapered shielding ring, said shielding ring Formed in curls of hard material with a dark coating on the inner surface.