Non-contact alcohol concentration detection system based on photoelectric method

Abstract

The utility model provides a non-contact alcohol concentration detection system based on a photoelectric method, and relates to the technical field of alcohol concentration detection, the non-contact alcohol concentration detection system utilizes a laser light source to emit a laser beam, the laser beam is reflected by a plane mirror and then is emitted to a transparent cuvette containing alcohol to be detected, and the light refraction degree is different due to different alcohol concentrations; the positions of the refraction point and the reflection point and the position of the light spot irradiated on the photoresistor can change along with the change of the alcohol concentration, the cuvette refracts the laser beam emitted by the light path device and then irradiates on the photoresistor, and due to different refractive indexes, the light spot irradiated on the photoresistor can move according to the change of the alcohol concentration, so that the light spot is irradiated on the photoresistor. The photoresistor changes the resistance value according to the change of the light intensity, and the measurement module detects the resistance value of the photoresistor and converts the resistance value into a voltage signal to be displayed.

Description

Technical Field

[0001] This utility model relates to the field of alcohol concentration detection technology, specifically a non-contact alcohol concentration detection system based on photoelectric method. Background Technology

[0002] Alcohol concentration measurement has wide applications in laboratories, production lines, and chemical engineering. Most existing alcohol concentration measurement methods rely on traditional wet chemical analysis, gas chromatography, and refractive index methods. Traditional wet chemical analysis requires chemical reactions to measure alcohol concentration, such as acid-base titration and redox titration. While providing high-precision results, these methods are complex, time-consuming, and consume reagents, generating chemical waste. Gas chromatography can accurately determine alcohol concentration and analyze the concentration of multiple components; however, it requires expensive equipment and high maintenance costs, and the operation is cumbersome, requiring specialized personnel and is unsuitable for rapid on-site testing, typically limited to laboratory use. The refractive index method calculates alcohol concentration by measuring the refractive index of a solution, which is relatively simple in principle. However, this method relies on a specialized refractometer, which needs to be in contact with the sample, making it susceptible to sample contamination or air bubbles in the solution, leading to inaccurate readings.

[0003] To address this issue, traditional solutions are based on optical principles, primarily calculating alcohol concentration by measuring the refractive index of the alcohol solution or the propagation characteristics of light. For example, CN220730003U discloses a non-contact alcohol concentration detector that utilizes near-infrared laser technology to penetrate the alcohol solution non-contactly and photoelectric detection technology to detect the intensity of transmitted light. Combined with a temperature compensation model, it achieves non-contact measurement of alcohol concentration. However, this method relies on sensors for ambient temperature and the internal temperature of the black box for temperature compensation, and its accuracy is greatly affected by interference factors. Furthermore, the high-precision components such as near-infrared lasers, photoelectric detectors, and temperature sensors are costly and require certain professional knowledge and operational skills. Therefore, it is essential to provide a new type of non-contact alcohol concentration detection system. Utility Model Content

[0004] The purpose of this invention is to provide a non-contact alcohol concentration detection system based on photoelectric method to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] A non-contact alcohol concentration detection system based on photoelectric method, comprising:

[0007] An optical path device, comprising a laser source and a plane mirror, wherein the laser source emits a laser beam which is reflected by the plane mirror and directed toward the cuvette;

[0008] A cuvette, which is a transparent container, is used to hold the alcohol to be tested and to refract the laser beam emitted by the optical path device onto the photoresistor.

[0009] A photoresistor, which is electrically connected to the measurement module, is used to sense the refracted light beam passing through the cuvette and change its resistance value according to the position change of the refracted light beam on the photoresistor.

[0010] The measurement module is used to detect the resistance value of the photoresistor and convert the resistance value into a voltage signal for display.

[0011] Furthermore, the laser source is a red laser source with a wavelength of 650nm, which is placed at the starting position of the optical path device to emit a laser beam to the plane mirror. The plane mirror is positioned between the laser source and the cuvette, forming an incident angle with the laser source to reflect the laser beam emitted by the laser source onto the cuvette. The angle between the laser beam reflected by the plane mirror and the side of the cuvette is 25 degrees.

[0012] Furthermore, the photoresistor is covered with a light shield, and the light shield has a light-transmitting hole on the side of the photosensitive layer near the photoresistor. The shape and size of the light-transmitting hole are the same as the shape and size of the laser beam interface emitted by the laser source.

[0013] When the cuvette contains pure water, the laser beam, after being refracted by the cuvette, passes completely through the light-transmitting hole and irradiates the photosensitive layer of the photoresistor.

[0014] Furthermore, the measurement module includes a measurement circuit, a voltage amplification circuit, a control module, and a display module. The measurement circuit is electrically connected to the photoresistor and is used to measure the resistance value of the photoresistor and convert it into a voltage signal. The voltage amplification circuit is electrically connected to the measurement circuit and is used to amplify the voltage signal. The control module is electrically connected to the voltage amplification circuit and the display module and is used to receive the amplified voltage signal and display it through the display module.

[0015] Furthermore, the measurement circuit includes resistors R1, R2, and R3 connected in series. The two ends of the photoresistor are electrically connected to resistors R2 and R3, respectively. The photoresistor and resistors R1, R2, and R3 form a ring structure. The two ends of resistor Rg are electrically connected to the connection node of resistors R1 and R3, and the connection node of resistor R2 and photoresistor, respectively. A voltage source Us and a switch K are connected in series between the connection node of resistors R1 and R2 and the connection node of resistor R3 and photoresistor. The two ends of resistor Rg serve as the two output terminals of the measurement circuit.

[0016] Furthermore, the voltage amplification circuit includes an operational amplifier U1. The inverting input terminal of the operational amplifier U1 is electrically connected to one end of the measurement circuit through a resistor R4, and the other end of the measurement circuit is grounded. The inverting input terminal of the operational amplifier U1 is also electrically connected to the power supply Vs through a resistor R5.

[0017] The output of operational amplifier U1 is grounded through series resistors R9 and R10. The non-inverting input is electrically connected to the connection point of resistors R9 and R10. The output of operational amplifier U1 is also electrically connected to the non-inverting input of operational amplifier U2 through resistor R6. The inverting input of operational amplifier U2 is grounded through resistor R7. The inverting input and output of operational amplifier U2 are electrically connected through resistor R8. The output of operational amplifier U2 serves as the output of the voltage amplification circuit and is electrically connected to the control module.

[0018] Furthermore, the optical path device, cuvette, and photoresistor are all located inside a sealed dark room.

[0019] Compared with the prior art, the beneficial effects of this utility model are:

[0020] This invention utilizes a laser light source to emit a laser beam, which is reflected by a plane mirror and directed onto a transparent cuvette containing the alcohol to be tested. Different alcohol concentrations cause varying degrees of light refraction, altering the positions of the refraction and reflection points, as well as the position of the light spot on the photoresistor. The cuvette refracts the laser beam emitted by the optical path device and projects it onto the photoresistor. Due to the different refractive indices, the light spot on the photoresistor moves according to the change in alcohol concentration, thus altering the area and intensity of light irradiation on the photoresistor. The photoresistor changes its resistance value according to the change in light intensity. The measurement module detects the resistance value of the photoresistor and converts it into a voltage signal for display. This system requires no complex chemical reactions or expensive equipment, is easy to operate, fast to detect, low in cost, and its non-contact detection avoids sample contamination while providing relatively accurate measurement of alcohol concentration. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0022] Figure 2 This is a top view of the present invention;

[0023] Figure 3 This is a schematic diagram of the measurement module in this utility model;

[0024] Figure 4 This is a circuit diagram of the measurement module in this utility model;

[0025] Figure 5This is a circuit diagram of the measuring circuit in this utility model;

[0026] Figure 6 This is a circuit diagram of the voltage amplifier circuit in this utility model;

[0027] Figure 7 This is a schematic diagram showing the disassembled connection of the light shield and the photoresistor in this utility model;

[0028] Figure 8 This is a schematic diagram showing the connection between the light shield and the photoresistor in this utility model.

[0029] In the diagram: 10 Optical path device, 11 Laser source, 12 Plane mirror, 20 Cuvette, 30 Photoresistor, 31 Light shield, 32 Light-transmitting hole, 40 Measurement module, 41 Measurement circuit, 42 Voltage amplifier circuit, 43 Control module, 44 Display module. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] Example:

[0032] Please see Figures 1 to 8 This utility model provides a technical solution:

[0033] A non-contact alcohol concentration detection system based on photoelectric method includes an optical path device 10, a cuvette 20, a photoresistor 30, and a measurement module 40, wherein:

[0034] The optical path device 10 includes a laser source 11 and a plane mirror 12. The laser source 11 emits a laser beam, which is reflected by the plane mirror 12 and directed towards the cuvette 20. The laser source 11 is a red laser source with a wavelength of 650 nm. Alcohol has a low absorption intensity for 650 nm red laser light, mainly due to the spectral absorption characteristics of its molecular structure. Ethanol's main absorption peaks are concentrated in the ultraviolet and infrared bands, while its absorption capacity in the visible light range is extremely weak. When using a 650 nm red laser source, the absorption of alcohol will not significantly affect the transmission of the laser, and the direct absorption of the laser is weak. At the same time, a 650 nm wavelength red laser beam is easy to focus. Suitable for precision photoelectric detection systems, the laser source 11 is placed at the starting position of the optical path device 10 to emit a laser beam to the plane mirror 12. The plane mirror 12 can effectively change the direction of light propagation, accurately guiding the laser beam into the cuvette 20 at an appropriate incident angle. The laser beam reflected by the plane mirror 12 can reduce light loss and avoid unnecessary scattering, so that the beam entering the cuvette 20 has sufficient intensity. The plane mirror 12 is placed between the laser source 11 and the cuvette 20, forming an incident angle with the laser source 11, to reflect the laser beam emitted by the laser source 11 onto the cuvette 20.

[0035] The cuvette 20 is used to hold the alcohol to be tested and refracts the laser beam emitted by the optical path device 10 onto the photoresistor 30. The cuvette 20 is made of optical-grade glass or transparent plastic to ensure good light transmittance. Materials include quartz glass and polymethyl methacrylate. The cuvette 20 is cuboid. The angle between the laser beam reflected by the plane mirror 12 and the side of the cuvette 20 is 25 degrees. The side receiving the reflected laser beam is perpendicular to the normal of the incident laser beam. The top of the cuvette 20 is open to facilitate the addition of samples. A removable lid can also be provided to prevent sample evaporation or contamination. Two sides of the cuvette 20 are transparent to allow light from lasers or other light sources to pass through. The quality of the light-transmitting surface directly affects the accuracy of the measurement. When monitoring alcohol concentration, it is necessary to ensure that the liquid added to the cuvette 20 meets the requirements for light refraction.

[0036] When a beam of light enters another medium, partial reflection and partial refraction occur according to the basic physical properties of light. Ethanol has a refractive index of approximately 1.36, which is higher than that of air (approximately 1.00). This higher refractive index causes the beam to refract upon entering the alcohol solution, changing its propagation direction. Reflectivity can be calculated using Fresnel's formula, but in general, for perpendicular incidence at the interface, the calculation is relatively simple. When the laser is incident at a 25-degree angle, the reflectivity is slightly higher than that for perpendicular incidence, but still low. In the case of low incident angles and highly transparent materials, the reflectivity is typically very low (within a few percentage points), and most of the light enters the alcohol solution. Because ethanol has a higher refractive index than air, the laser light refracts towards the normal direction when it enters the cuvette. Cuvettes are commonly made of quartz glass or PMMA (polymethyl methacrylate). Their high light transmittance ensures the efficiency of laser light passing through the cuvette. The cuboid design helps control the light path and reduce light loss. The laser is incident at a 25-degree angle, and the carefully designed angle ensures that the beam can effectively propagate inside the cuvette and exit from the other side. As can be seen, in a cuvette containing an alcohol solution, a well-designed optical path and material selection can ensure that the laser beam is effectively refracted and emitted, facilitating subsequent photoelectric detection or analysis.

[0037] The photoresistor 30 is electrically connected to the measurement module 40 and is used to sense the refracted light passing through the cuvette 20. The resistance value of the photoresistor 30 is changed according to the position change of the refracted light beam on the photoresistor 30. The photoresistor 30 is a 12528 model photoresistor that is sensitive to visible light and has a specification of 12mm.

[0038] The photoresistor 30 is covered by a light-shielding cover 31. The light-shielding cover 31 has a light-transmitting hole 32 on the side of the photosensitive layer near the photoresistor 30. The shape and size of the light-transmitting hole 32 are the same as the shape and size of the laser beam interface emitted by the laser source 11. When the cuvette 20 contains pure water, the laser beam, after refraction by the cuvette 20, passes completely through the light-transmitting hole 32 and irradiates the photosensitive layer of the photoresistor 30. When the cuvette 20 contains water, the laser beam can just completely pass through the light-transmitting hole 32 and irradiate the photoresistor 30. When it contains alcohol... Because the refractive index varies with different alcohol concentrations, the positions of the refraction point, reflection point, and the position of the light spot illuminating the photoresistor 30 will change with the alcohol concentration. As the alcohol concentration increases, the light spot gradually moves outward from the light-transmitting hole 32, and its area through the light-transmitting hole 32 decreases. The relative area gradually changes from 1 to 0. Therefore, the alcohol concentration is related to the position of the light spot illuminating the photoresistor 30 (i.e., the area of ​​the light spot illuminating the photoresistor 30), resulting in a change in resistance. The light shield 31 is made of black ABS plastic, which has good surface light absorption and strong light-shielding ability.

[0039] The measurement module 40 is used to detect the resistance value of the photoresistor 30 and convert the resistance value into a voltage signal for display. The measurement module 40 includes a measurement circuit 41, a voltage amplification circuit 42, a control module 43, and a display module 44. The measurement circuit 41 forms a specific circuit structure through series resistors and is electrically connected to the photoresistor 30. It is used to measure the resistance value of the photoresistor 30 and convert it into a voltage signal. The voltage amplification circuit 42 is electrically connected to the measurement circuit 41 and is used to amplify the voltage signal. The control module 43 is electrically connected to the voltage amplification circuit 42 and the display module 44 and is used to receive the amplified voltage signal and display it through the display module 44.

[0040] The control module 43 is used to read the signal output by the voltage amplifier circuit 42, process the signal, and finally drive the display module 44 to display it. The display module 44 is used to display the specific value of the amplified voltage signal and provide the user with readable output results.

[0041] The display module 44 uses an SSD1306 OLED display, and the control module 43 uses an Arduino Uno-based microcontroller. The power pins of the display module 44 are connected to the power supply section of the control module 43, the ground pin is connected to GND, and the data pins are connected to the digital pins of the control module 43 to realize data transmission and control display.

[0042] The measurement circuit 41 is a typical bridge measurement circuit, including resistors R1, R2, and R3 connected in series. The photoresistor 30 is electrically connected to resistors R2 and R3 respectively. The photoresistor 30 and resistors R1, R2, and R3 form a ring structure. Resistor Rg is electrically connected to the connection point of resistors R1 and R3, and the connection point of resistor R2 and photoresistor 30 respectively. A voltage source Us and a switch K are connected in series between the connection points of resistors R1 and R2 and the connection point of resistor R3 and photoresistor 30. The two ends of resistor Rg serve as the two output terminals of the measurement circuit 41. When the bridge is balanced, no current flows through the galvanometer Rg. Knowing the resistance values ​​of R1, R2, and R3, the value of the photoresistor 30 can be calculated. When the bridge is unbalanced, current flows through the galvanometer Rg, and simultaneously Us... out When the output voltage is not zero, the change of photoresistor 30 can be calculated using the nodal voltage method based on the value of the output voltage and the circuit parameters.

[0043] The voltage amplifier circuit 42 is a voltage amplifier circuit composed of two operational amplifiers U1 and U2. The operational amplifier U1 adopts a non-inverting amplification structure. The inverting input terminal of the operational amplifier U1 is electrically connected to one end of the measurement circuit 41 through the resistor R4, and the other end of the measurement circuit 41 is grounded. The inverting input terminal of the operational amplifier U1 is also electrically connected to the power supply Vs through the resistor R5. The operational amplifier U1 adopts a general-purpose operational amplifier LM741. According to the characteristics of "virtual short" and "virtual open" of the operational amplifier, the output voltage of the operational amplifier U1 is amplified according to the input voltage signal and the feedback resistor.

[0044] The output terminal of operational amplifier U1 is grounded through series resistors R9 and R10. The non-inverting input terminal is electrically connected to the connection node of resistors R9 and R10. The output terminal of operational amplifier U1 is also electrically connected to the non-inverting input terminal of operational amplifier U2 through resistor R6. The inverting input terminal of operational amplifier U2 is grounded through resistor R7. The inverting input terminal and output terminal of operational amplifier U2 are electrically connected through resistor R8. The output terminal of operational amplifier U2 serves as the output of voltage amplifier circuit 42 and is electrically connected to control module 43. The operational amplifier U2 uses operational amplifier LM324. The input signal is further amplified through the feedback network composed of R7 and R8 to make it strong enough for display and processing.

[0045] The optical path device 10, cuvette 20, and photoresistor 30 are all located inside a sealed darkroom 50 to prevent the influence of external light sources and improve the accuracy of the measurement.

[0046] Darkroom 50 is an openable box made of thick wood or plywood, coated with black anti-light paint on the outside and black on the inside to reduce internal light reflection and ensure good airtightness. Gaps in the box must be sealed with black tape or rubber sealing strips to prevent external light from leaking in. Inside the box, the optical path device 10, cuvette 20, and photoresistor 30 are installed. The laser light source 11 should be fixed on one side to ensure that the light can directly illuminate the cuvette 20. The cuvette 20 should be placed in the center of the optical path, and the photoresistor 30 should be placed after the light passes through the cuvette 20 to ensure that its sensitivity to light is maximized.

[0047] Ensuring sufficient space at the opening of the box for quick opening, and placing the optical path device 10, cuvette 20, and photoresistor 30 inside a sealed darkroom 50, is primarily to ensure the accuracy and reliability of the experiment or measurement. The darkroom 50 effectively isolates external light sources, avoiding interference from ambient light on the measurement results, thereby improving the response accuracy of the photoresistor 30 and the measurement accuracy of the colorimetric method. Within the darkroom 50, the light intensity and spectral characteristics of the optical path device 10 remain stable, helping to obtain consistent measurement conditions and reducing errors caused by environmental changes.

[0048] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A non-contact alcohol concentration detection system based on the photoelectric method, characterized in that, Include: Optical path device (10), the optical path device (10) includes laser light source (11) and plane mirror (12), the laser light source (11) is used to emit laser beam, after reflecting through plane mirror (12) to colorimetric cup (20); Colorimetric cup (20), the colorimetric cup (20) is transparent container, for containing alcohol to be detected, and the laser beam emitted by optical path device (10) is refracted and irradiated on photoresistor (30); Photoresistor (30), the photoresistor (30) is electrically connected with measurement module (40), for sensing the refracted light beam through colorimetric cup (20), and changing the resistance value according to the position change of the refracted light beam irradiated on photoresistor (30); Measurement module (40), the measurement module (40) is used to detect the resistance value of photoresistor (30), and converts the resistance value into voltage signal for display.

2. The non-contact alcohol concentration detection system based on the optoelectronic method according to claim 1, characterized in that, The laser light source (11) is a red laser light source with a wavelength of 650nm, placed at the starting position of the optical path device (10), for emitting laser beam to the plane mirror (12), the plane mirror (12) is arranged between the laser light source (11) and the colorimetric cup (20), and forms an incident angle with the laser light source (11), for reflecting the laser beam emitted by the laser light source (11) to the colorimetric cup (20), the angle between the laser beam reflected by the plane mirror (12) and the side of the colorimetric cup (20) is 25 degrees.

3. The non-contact alcohol concentration detection system based on the optoelectronic method according to claim 1, characterized in that, The photoresistor (30) is externally sleeved with a light shield (31), the light shield (31) is provided with a light transmission hole (32) on the side close to the photosensitive layer of the photoresistor (30), the shape and size of the light transmission hole (32) are same with the interface shape and size of the laser beam emitted by the laser light source (11); When the colorimetric cup (20) contains pure water, the laser beam refracted through the colorimetric cup (20) is completely transmitted through the light transmission hole (32) and irradiated on the photosensitive layer of the photoresistor (30).

4. The non-contact alcohol concentration detection system based on the optoelectronic method according to claim 1, characterized in that, The measurement module (40) includes measurement circuit (41), voltage amplification circuit (42), control module (43) and display module (44), the measurement circuit (41) and photoresistor (30) are electrically connected, for measuring the resistance value of photoresistor (30), and converting into voltage signal, the voltage amplification circuit (42) and measurement circuit (41) are electrically connected, for amplifying the voltage signal, the control module (43) and voltage amplification circuit (42), display module (44) are electrically connected, for receiving the amplified voltage signal and displaying through display module (44).

5. The non-contact alcohol concentration detection system based on the optoelectronic method according to claim 4, characterized in that, The measuring circuit (41) comprises resistors R1, R2 and R3 connected in series, the photoresistor (30) is electrically connected to the resistors R2 and R3 respectively, the photoresistor (30) and the resistors R1, R2 and R3 form a ring structure, the resistor Rg is electrically connected to the connection nodes of the resistors R1 and R3 and the connection nodes of the resistor R2 and the photoresistor (30) respectively, the voltage source Us and the switch K are connected in series between the connection nodes of the resistors R1 and R2 and the connection nodes of the resistor R3 and the photoresistor (30), and the two ends of the resistor Rg serve as two output ends of the measuring circuit (41).

6. The non-contact alcohol concentration detection system based on optoelectronic method as claimed in claim 4, wherein, The voltage amplification circuit (42) comprises an operational amplifier U1, the reverse input end of the operational amplifier U1 is electrically connected to one end of the measuring circuit (41) through the resistor R4, the other end of the measuring circuit (41) is grounded, and the reverse input end of the operational amplifier U1 is also electrically connected to the power supply Vs through the resistor R5; the output end of the operational amplifier U1 is grounded through the resistors R9 and R10 connected in series, the same-phase input end is electrically connected to the connection node of the resistors R9 and R10, the output end of the operational amplifier U1 is also electrically connected to the same-direction input end of the operational amplifier U2 through the resistor R6, the reverse input end of the operational amplifier U2 is grounded through the resistor R7, the reverse input end and the output end of the operational amplifier U2 are electrically connected through the resistor R8, the output end of the operational amplifier U2 serves as the output of the voltage amplification circuit (42) and is electrically connected to the control module (43).

7. The non-contact alcohol concentration detection system based on optoelectronic method according to any one of claims 1-6, characterized in that, The light path device (10), the cuvette (20) and the photoresistor (30) are located inside a closed darkroom (50).

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