A device for detecting liquid refractive index based on transmission light path

Abstract

The utility model discloses a device for detecting the refractive index of liquid based on a transmission light path and a detection method thereof, comprising a laser, a sample pool, a thermostatic bath, a photoelectric imaging device, a control unit, and a PC, wherein the sample pool is light-transmissive in front and back, and one or both walls of the light-transmissive surface are a wedge-shaped structure of a right-angled trapezoid, the thermostatic bath can control the temperature of the liquid sample, and the laser emitted by the laser penetrates through the liquid sample in the sample pool and finally forms an image on the photoelectric imaging device placed in the transmission direction. The utility model realizes the detection of the refractive index of the liquid with an accuracy better than 0.05%.

Description

Technical Field

[0001] The utility model relates to a device for detecting the refractive index of liquid, in particular to a device for detecting the refractive index of liquid based on a transmission light path. Background Art

[0002] The refractive index of a liquid is also called the refractive index or refractive index. It is an important optical physical parameter of the liquid and affects the scattering vector of the test system. The scattering vector is a parameter that needs to be calculated in several test processes, such as particle size test technology based on dynamic light scattering theory, Zeta potential test technology based on electrophoretic light scattering theory, etc. The accuracy of the liquid refractive index has an important influence on the accuracy of the results. It can be seen from theoretical calculations that in dynamic light scattering technology, a 1% refractive index error will lead to a 2.4% particle size calculation error.

[0003] The traditional liquid refractive index detection method based on the transmission light path uses a laser beam to be incident on a tilted rectangular sample cell filled with liquid, where the front and rear walls of the rectangular sample cell are parallel glass plates or quartz plates. The light is refracted at the interface between the air and the cell wall and the interface between the liquid medium and the cell wall during the process of passing through the sample cell, where the refraction angle conforms to the law of refraction. The outgoing light after the light passes through the sample cell is parallel to the direction of the incident light, and a certain offset occurs in height. The offset is related to the refractive index of the liquid in the sample cell. The refractive index value of the liquid can be obtained through the relationship between the offset and the refractive index of the liquid. Although this method is simple, it requires a large tilt angle of the sample cell and a long travel distance of the light in the liquid to ensure sufficient offset. The required sample volume is usually 1mL or more, which cannot meet the needs of micro-sample testing. Taking the commonly used glass cuvette with an inner diameter of 10mm x 10mm and a wall thickness of 1.2mm as an example, when the sample cell is tilted 5°, the optical path height offset corresponding to the liquid refractive index increasing from 1.33 to 1.49 is about 0.072mm; when the sample cell is tilted 10°, the optical path height offset corresponding to the liquid refractive index increasing from 1.33 to 1.49 is about 0.14mm. Considering that the laser spot size is usually above 100 microns and the accuracy of detecting the offset is in the range of 4-6μm, the smaller optical path offset increases the difficulty of detecting the liquid refractive index. The accuracy of this type of structure for detecting the liquid refractive index is about 1-2%. Utility Model Content

[0004] In view of the problem of low accuracy of existing methods for detecting refractive index based on transmitted light paths, the problem to be solved by the utility model is to provide a device for detecting liquid refractive index based on transmitted light paths and a detection method thereof, which provides liquid refractive index detection with an accuracy better than 0.05%.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0006] A detection device for detecting the refractive index of a liquid based on light path refraction, comprising a laser, a sample cell, a constant temperature bath, a photoelectric imaging device, a control unit and a PC;

[0007] The sample pool contains a liquid sample to be tested;

[0008] The sample pool is light-transmissive at the front and back, and one or both walls of the light-transmissive surface are right-angled trapezoidal wedge-shaped glass. The laser emitted by the laser penetrates through the liquid sample in the sample pool and finally forms an image on the photoelectric imaging device placed in the transmission direction; the control unit is used to receive PC instructions and output control signals to control the temperature of the constant temperature bath to control the temperature of the sample, thereby avoiding the influence of temperature deviation on the refractive index determination.

[0009] The detection device for detecting the refractive index of liquid based on light path refraction, its preferred embodiment is that the sample pool is designed with two transparent sides, made of quartz glass or K9 glass, and uses a melting process to tolerate aqueous samples and organic samples, wherein the two transparent surfaces of the sample pool adopt two designs; the sample pool design one is that the pool wall on one side of the transparent surface of the sample pool is a parallel glass plate, and the pool wall on the other side of the transparent surface is a right-angled trapezoidal wedge-shaped glass, and its oblique waist side is located on the inner side of the sample pool.

[0010] The second sample pool design is a wedge-shaped glass with right-angle trapezoidal shapes on both sides of the sample pool's light-transmitting surface, and its oblique waist side is located inside the sample pool. The sample volume required for both designs is less than 350 microliters.

[0011] The detection device for detecting the refractive index of liquid based on light path refraction, its preferred solution is to design the angle between the oblique waist and the right-angle waist on one side of the wedge-shaped glass to be between 5° and 12°, and to design the sum of the angles between the oblique waist and the right-angle waist on both sides of the wedge-shaped glass to be between 5° and 12°.

[0012] The detection device for detecting the refractive index of liquid based on light path refraction, its preferred embodiment is that the laser of the laser passes through four interfaces in sequence when passing through the sample pool, namely the interface between the air and the outer wall of the glass pool wall on the laser incident side, the interface between the inner wall of the glass pool wall on the laser incident side and the liquid, the interface between the liquid and the inner wall of the glass pool wall on the laser exit side and the interface between the outer wall of the glass pool wall on the laser exit side and the air. After the laser passes through the sample pool, the direction of the exiting laser light path changes, and the variable of its direction change is related to the refractive index of the sample.

[0013] The detection device for detecting the refractive index of liquid based on light path refraction has a preferred solution in which the sample cell can be placed vertically or tilted, with the tilt angle being less than 10°, and the direction of the laser emission light path is changed.

[0014] The preferred embodiment of the detection device for detecting the refractive index of liquid based on light path refraction is that the laser beam profile of the laser is circular and the light spot projection is circular.

[0015] The preferred embodiment of the detection device for detecting the refractive index of liquid based on light path refraction is that after the laser passes through the sample, its light spot is imaged on the photoelectric imaging device, and the photoelectric imaging device can detect the position of the center point of the light spot imaging with high precision. Since the laser is refracted after passing through the sample pool, the light spot imaging position deviates from the direction of the incident laser, and the refractive index of the sample is calculated based on the relationship between the position of the center point of the light spot imaging and the refractive index.

[0016] The preferred embodiment of the detection device for detecting the refractive index of liquid based on light path refraction is that the distance between the photoelectric imaging device and the central axis of the sample pool is set within the range of 25mm-75mm. The position of the center point of the light spot imaging is related to the distance from the sample pool to the photoelectric imaging device. The farther the distance, the greater the imaging position offset.

[0017] The preferred solution of the detection device for detecting the refractive index of liquid based on light path refraction is to use a high-resolution photoelectric imaging device, the photosensitive surface of the photoelectric imaging device is arranged perpendicular to the laser incident direction, and the photoelectric imaging device includes CCD and CMOS.

[0018] The preferred embodiment of the detection device for detecting the refractive index of liquid based on light path refraction is that, within the range of the sample refractive index of 1.2 to 1.6, there is a linear relationship between the position of the center point of the light spot imaging and the refractive index.

[0019] A detection method of a detection device for detecting the refractive index of a liquid based on light path refraction, comprising the following steps:

[0020] 1) Inject a liquid sample with a known refractive index into a sample cell, then place the sample cell in a constant temperature bath and perform a constant temperature operation to make the sample reach the target temperature;

[0021] 2) By analyzing the light spot projection on the optoelectronic imaging device, the position of the center point of the light spot imaging in the vertical coordinate direction is obtained;

[0022] 3) Repeat steps 1)-2) to detect the vertical position of the center point of the light spot of 2-5 liquid samples with known refractive index;

[0023] 4) Draw a calibration curve using the refractive index and vertical position of the sample; wherein the calibration curve is drawn by linearly fitting the position data points of the sample with known refractive index, and the linear correlation coefficient R 2 Better than 0.99, the extended calibration curve can still be used for effective detection of samples with unknown refractive index.

[0024] 5) Inject a liquid sample of unknown refractive index, repeat steps 1)-2), detect the vertical position of the center point of the light spot of the liquid sample of unknown refractive index, and then find its corresponding refractive index on the calibration curve.

[0025] A detection method for a detection device for detecting the refractive index of a liquid based on light path refraction. The method and device can be integrated into a nanoparticle size and Zeta potential instrument based on dynamic light scattering technology and electrophoretic light scattering technology. The sample is kept at a constant temperature using a thermostat of the nanoparticle size and Zeta potential instrument, and the refractive index is tested using a laser light source of the nanoparticle size and Zeta potential instrument. The refractive index of the liquid at the wavelength and temperature can be obtained and used for calculating the particle size and Zeta potential, thereby avoiding the influence of different wavelengths and temperatures on the refractive index of the liquid.

[0026] Beneficial Effects

[0027] 1. The utility model utilizes the refractive behavior of laser in different refractive index media in the transmission light path to realize the test of the refractive index of liquid. The device can be integrated in a nanoparticle size and Zeta potential meter based on dynamic light scattering technology and electrophoretic light scattering technology, using the laser light source of the nanoparticle size and Zeta potential meter as the detection light source of the refractive index, using a constant temperature bath to keep the sample at a constant temperature, and using the refractive index of the liquid detected to calculate the particle size and Zeta potential of the nanoparticle size and Zeta potential meter, eliminating the influence of different wavelengths and different temperatures on the liquid refractive index detection results, and further increasing the accuracy of particle size and Zeta potential detection. The device has great promotion and practical value, and will produce good economic and social benefits after widespread promotion and application;

[0028] 2. The utility model accurately controls the temperature of the sample, and the temperature control accuracy reaches ±0.1°C, avoiding the influence of temperature deviation on the refractive index measurement;

[0029] 3. The sample pool design 1 adopted in the present invention is that the pool wall on one side of the sample pool's light-transmitting surface is a parallel glass plate, and the pool wall on the other side of the light-transmitting surface is a wedge-shaped glass with a right-angled trapezoidal cross section, and its oblique waist side is located inside the sample pool; Design 2 is that both sides of the sample pool's light-transmitting surface are wedge-shaped glass with a right-angled trapezoidal cross section, and its oblique waist side is located inside the sample pool. After the laser passes through the sample pool, the direction of its outgoing light path changes, and the variable of its direction change is related to the sample's refractive index. When the sample's refractive index is between 1.2-1.6, there is a linear relationship between the position of the center point of the light spot imaging and the refractive index;

[0030] 4. The utility model adopts a transmission light path structure, and the position offset of the center point of the light spot imaging reaches the millimeter level when the sample refractive index is between 1.2 and 1.6, which can effectively reduce the error caused by the uncertainty of the center position of the confirmed light spot to the detection result, and the detection accuracy of the liquid refractive index is better than 0.05%.

[0031] 5. The two sample pools used in the present invention require a sample volume of less than 350 μL, which can meet the needs of testing trace sample volumes;

[0032] 6. The utility model adopts a high-resolution photoelectric imaging device, the photosensitive surface of the photoelectric imaging device is arranged perpendicular to the laser incident direction, and the photoelectric imaging device includes CCD and CMOS, which can meet the needs of high-precision refractive index testing;

[0033] 7. The utility model is widely used in precision electrical, electronic, instrumentation and other products, and is mainly used in research and application fields such as medical care, biopharmaceuticals, agricultural scientific research, and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The electrical principle block diagram of the device for detecting the refractive index of liquid based on the transmission light path;

[0035] Figure 2 A is a schematic diagram of the structure of the sample pool for design 1; B is a schematic diagram of the structure of the sample pool for design 2;

[0036] Figure 3 A in the figure is a schematic diagram of the refraction of laser light in a sample cell designed to be placed vertically;

[0037] B is a schematic diagram of the refraction of the laser in the sample cell when the first sample cell is tilted; C is a schematic diagram of the refraction of the laser in the sample cell when the second sample cell is vertically placed; D is a schematic diagram of the refraction of the laser in the sample cell when the second sample cell is tilted;

[0038] Figure 4 A is a schematic diagram of the distance between the axis line and the photoelectric imaging device when the sample pool design 1 is placed vertically; B is a schematic diagram of the distance between the axis line and the photoelectric imaging device when the sample pool design 1 is placed tilted; C is a schematic diagram of the distance between the axis line and the photoelectric imaging device when the sample pool design 2 is placed vertically; D is a schematic diagram of the distance between the axis line and the photoelectric imaging device when the sample pool design 2 is placed tilted;

[0039] Figure 5 A schematic diagram of imaging a laser spot on an optoelectronic imaging device and confirming the vertical position of the center point of the spot;

[0040] Figure 6 A schematic diagram of drawing a calibration curve and calculating the light index of an unknown sample for the method of the utility model;

[0041] Figure 7 A is an example of the vertical position of the center point of the light spot within the range of 1.2 to 1.6 of the refractive index caused by different distances between the photoelectric imaging device and the central axis of the sample cell in the first sample cell design of the utility model; B is an example of the imaging position of the light spot within the range of 1.2 to 1.6 of the refractive index caused by different angles between the oblique waist and the right-angle waist in the first sample cell design of the utility model; C is an example of the imaging position of the light spot within the range of 1.2 to 1.6 of the refractive index caused by different sample cell inclination angles in the first sample cell design of the utility model;

[0042] Figure 8 This is an example of the imaging position of the light spot within the range of 1.2 to 1.6 of the refractive index caused by the sample cell design 1 and the sample cell design 2 of the utility model under the same oblique waist and right-angle waist angle conditions.

[0043] Among them, 1 is sample pool design 1, 2 is sample pool design 2, 3 is sample, 4 is parallel plate glass, 5 is wedge glass, 6 is right-angle waist, 7 is oblique waist, 8 is the angle between oblique waist and right-angle waist, 9 is incident laser, 10 is exiting laser, 11 is the incident laser extension line, 12 is photoelectric imaging device, 13 is the interface between air and the outer wall of the glass pool wall on the laser incident side, 14 is the interface between the inner wall of the glass pool wall on the laser incident side and liquid, 15 is the interface between liquid and the inner wall of the glass pool wall on the laser exit side, 16 is the interface between the outer wall of the glass pool wall on the laser exit side and air, 17 is The inclination angle of the sample pool, 18 is the center axis of the sample pool, 19 is the distance between the photoelectric imaging device and the center axis of the sample pool, 20 is the light spot, 21 is the center point of the light spot imaging, 22 is the vertical position of the center point of the light spot imaging, 23 is the vertical coordinate, 24 is the calibration curve, 25 is the extension line of the calibration curve, 26 is the vertical position of the center point of the light spot of the liquid sample with a known refractive index, 27 is the refractive index of the liquid with a known refractive index, 28 is the vertical position of the center point of the light spot of the liquid sample with an unknown refractive index, and 29 is the refractive index of the liquid with an unknown refractive index. DETAILED DESCRIPTION

[0044] The utility model will be further described below in conjunction with the accompanying drawings of the specification.

[0045] like Figure 1-8 As shown, the utility model provides a device for detecting the refractive index of liquid based on a transmission light path, characterized in that it includes a laser, a sample pool, a constant temperature bath, a photoelectric imaging device 12, a control unit and a PC; the sample pool is light-transmissive at the front and back, and one or both walls of the light-transmitting surface are right-angled trapezoidal wedge-shaped glass 5;

[0046] The laser light 9 emitted by the laser penetrates through the liquid sample 3 in the sample pool and finally forms an image on the photoelectric imaging device 12 placed in the transmission direction;

[0047] The control unit is used to receive PC instructions and output control signals to control the temperature of the constant temperature bath for sample 3 to avoid the influence of temperature deviation on the refractive index determination.

[0048] like Figure 2 As shown, the sample pool is designed to be light-transmissive on both sides, made of quartz glass or K9 glass, and uses a melting process to withstand aqueous and organic samples;

[0049] The two light-transmitting surfaces of the sample pool can be designed in two ways. Sample pool design 1 is that the pool wall on one side of the light-transmitting surface of the sample pool is a parallel glass plate 4, and the pool wall on the other side of the light-transmitting surface is a right-angled trapezoidal wedge-shaped glass 5, whose oblique waist 7 is located on the inner side of the sample pool.

[0050] The sample pool design 2 is that both sides of the sample pool light-transmitting surface are wedge-shaped glass 5 with a right-angle trapezoidal cross section, and one side of the oblique waist 7 is located inside the sample pool. The sample volume required for both designs is less than 350 microliters.

[0051] In design one of the sample pools, the angle 8 between the oblique waist 7 and the right-angle waist 6 on one side of the wedge-shaped glass 5 is between 5° and 12°, and in design two, the sum of the angles 8 between the oblique waist 7 and the right-angle waist 6 on both sides of the wedge-shaped glass is between 5° and 12°.

[0052] like Figure 3 As shown, the laser light 9 passes through four interfaces in sequence when passing through the sample pool, namely, the interface 13 between the air and the outer wall of the glass pool wall on the laser incident side, the interface 14 between the inner wall of the glass pool wall on the laser incident side and the liquid, the interface 15 between the liquid and the inner wall of the glass pool wall on the laser exit side, and the interface 16 between the outer wall of the glass pool wall on the laser exit side and the air. After the laser passes through the sample pool, the optical path direction of the exiting laser light 10 changes, and the variable of its direction change is related to the refractive index of the sample.

[0053] like Figure 3 As shown, the sample cell can be placed vertically or tilted at an angle 17 less than 10°, and the direction of the laser emission light path 10 is changed.

[0054] like Figure 5 As shown, the laser beam profile of the laser is circular, and the light spot 20 thereof is projected as a circle.

[0055] After the laser passes through the sample, its spot 20 is imaged on the photoelectric imaging device 12, and the photoelectric imaging device 12 can detect the position 22 of the center point 21 of the spot imaging with high precision. Since the laser is refracted after passing through the sample pools 1 and 2, the spot imaging position deviates from the direction of the incident laser 9, and the refractive index 29 of the sample is calculated based on the relationship between the center point position 22 of the spot imaging and the refractive index.

[0056] The distance between the photoelectric imaging device 12 and the central axis 18 of the sample pool is set within the range of 25mm-75mm. The center point position 22 of the light spot imaging is related to the distance 19 from the sample pool to the photoelectric imaging device. The farther the distance, the greater the imaging position offset.

[0057] A high-resolution photoelectric imaging device is used, and the photosensitive surface of the photoelectric imaging device 12 is arranged perpendicular to the laser incident direction 9. The photoelectric imaging device includes CCD and CMOS.

[0058] like Figure 6 As shown, when the sample refractive index is in the range of 1.2 to 1.6, there is a linear relationship between the position 22 of the center point of the light spot imaging and the refractive index.

[0059] like Figure 6 As shown, a calibration curve is drawn by using 2 to 5 samples with known refractive indexes and the refractive index of a sample with unknown refractive index is calculated. The specific steps include the following steps:

[0060] 1) Inject a liquid sample with a known refractive index of 27 into the sample cell, then place the sample cell in a constant temperature bath and perform a constant temperature operation to make the sample reach the target temperature;

[0061] 2) By analyzing the projection of the light spot 20 on the optoelectronic imaging device 12, the position 22 of the center point of the light spot imaging on the vertical coordinate 23 is obtained;

[0062] 3) repeating steps 1)-2) to detect the vertical position 26 of the center point of the light spot of 2-5 liquid samples with known refractive index;

[0063] 4) drawing a calibration curve 24 using the refractive index and vertical position of the sample;

[0064] 5) Inject a liquid sample with an unknown refractive index, repeat steps 1)-2), detect the vertical position 28 of the center point of the light spot of the liquid sample with an unknown refractive index, and then find its corresponding refractive index 29 on the calibration curve 24.

[0065] The calibration curve 24 in step 4) is drawn, and a linear fit is performed on the position data points of the sample with a known refractive index, and the linear correlation coefficient R 2 Better than 0.99, the calibration curve extension line 25 can still be used for effective detection of samples with unknown refractive index.

[0066] like Figure 7As shown in A, the sample pool is designed as 1, the angle between the fixed oblique waist and the right-angle waist is 5°, the fixed sample pool tilt angle is 0°, the distances between the photoelectric imaging device and the central axis of the sample pool are 25mm, 50mm and 70mm respectively, the refractive index is in the range of 1.2 to 1.6, the refractive index is linearly related to the vertical position of the center point of the light spot, the farther the distance, the greater the slope of the linear relationship, wherein the incident laser extension line 11 is at 0 in the vertical direction of the photoelectric imaging device 12;

[0067] like Figure 7 As shown in B, the sample pool is designed as 1, the fixed sample pool tilt angle is 0°, the distance between the fixed photoelectric imaging device and the sample pool centerline is 75 mm, the angles between the oblique waist and the right-angle waist are 5°, 7°, 10°, and 12°, respectively, and the refractive index is in the range of 1.2 to 1.6. The refractive index is linearly related to the vertical position of the center point of the light spot. The larger the angle between the oblique waist and the right-angle waist, the larger the slope of the linear relationship. The incident laser extension line 11 is at 0 in the vertical direction of the photoelectric imaging device 12;

[0068] like Figure 7 As shown in C, the sample pool is designed as 1, the angle between the fixed oblique waist and the right-angle waist is 5°, the distance between the fixed photoelectric imaging device and the central axis of the sample pool is 25 mm, the sample pool tilt angles are 0°, 5°, and 10°, and the refractive index is in the range of 1.2 to 1.6. The refractive index is linearly related to the vertical position of the center point of the light spot. The larger the tilt angle of the sample pool, the larger the slope of the linear relationship. The incident laser extension line 11 is at 0 in the vertical direction of the photoelectric imaging device 12;

[0069] like Figure 8 As shown, the inclination angle of the fixed sample pool is 5°, the distance between the fixed photoelectric imaging device and the central axis of the sample pool is 50 mm, the included angle between the oblique waist and the right-angle waist of sample pool design 1 is 10°, and the included angle between the oblique waist and the right-angle waist of the wedge-shaped glass on both sides of sample pool design 2 is 5° and the sum of the included angles is 10°. In the range of refractive index of 1.2 to 1.6, the refractive index is linearly related to the vertical position of the center of the light spot. Under the same conditions of the included angle of the oblique waist and the right-angle waist, the vertical position of the center of the light spot of the two designs is basically the same, and the slope of the linear relationship is basically the same.

[0070] A detection method for a device for detecting the refractive index of a liquid based on a transmission light path. The method and device can be integrated into a nanoparticle size and Zeta potential instrument based on dynamic light scattering technology and electrophoretic light scattering technology. The sample is kept at a constant temperature using a thermostat of the nanoparticle size and Zeta potential instrument, and the refractive index is tested using a laser light source of the nanoparticle size and Zeta potential instrument. The refractive index of the liquid at the wavelength and temperature can be obtained and used for calculating the particle size and Zeta potential, thereby avoiding the influence of different wavelengths and temperatures on the refractive index of the liquid.

Claims

1. A device for detecting the refractive index of liquid based on a transmission light path, characterized in that: Includes laser, sample pool, constant temperature bath, photoelectric imaging device, control unit and PC; The sample pool contains a liquid sample to be tested; The sample pool is light-transmissive at the front and back, and one or both walls of the light-transmissive surface are right-angled trapezoidal wedge-shaped glass; The laser emitted by the laser penetrates through the liquid sample in the sample pool and finally forms an image on the photoelectric imaging device placed in the transmission direction; The control unit is used to receive PC instructions and output control signals to control the temperature of the thermostatic bath to control the temperature of the sample, thereby avoiding the influence of temperature deviation on the refractive index determination; The distance between the photoelectric imaging device and the central axis of the sample pool is set within the range of 25mm-75mm; the position of the center point of the light spot imaging is related to the distance from the sample pool to the photoelectric imaging device, and the greater the distance, the greater the imaging position offset; Use high-resolution photoelectric imaging devices, the photosensitive surface of which is placed perpendicular to the incident direction of the laser. Photoelectric imaging devices include CCD and CMOS. The device can be integrated into a nanoparticle size and Zeta potential instrument based on dynamic light scattering technology and electrophoretic light scattering technology. The sample is kept at a constant temperature using a constant temperature bath of the nanoparticle size and Zeta potential instrument. The refractive index is tested using a laser light source of the nanoparticle size and Zeta potential instrument to obtain the refractive index of the liquid at the wavelength and temperature of the light source of the nanoparticle size and Zeta potential instrument. The refractive index is then used to calculate the particle size and Zeta potential, thereby avoiding the influence of different wavelengths and temperatures on the refractive index of the liquid.

2. The device for detecting the refractive index of liquid based on a transmission light path according to claim 1, characterized in that: The sample pool is designed to be light-transmissive on both sides, made of quartz glass or K9 glass, and uses a melting process to withstand aqueous and organic samples; The light-transmitting surface design of the sample pool includes two schemes. The first sample pool design is that the pool wall on one side of the light-transmitting surface of the sample pool is a parallel glass plate, and the pool wall on the other side of the light-transmitting surface is a right-angled trapezoidal wedge-shaped glass, and its oblique waist side is located on the inner side of the sample pool; The second sample pool design is a wedge-shaped glass with right-angle trapezoidal shapes on both sides of the sample pool's light-transmitting surface, and its oblique waist side is located on the inner side of the sample pool; The sample volume required for the above two designs is less than 350 μl.

3. The device for detecting the refractive index of liquid based on a transmission light path according to claim 2, characterized in that: The included angle between the oblique waist and the right-angle waist on one side of the wedge-shaped glass in Design 1 is between 5° and 12°, and the sum of the included angles between the oblique waist and the right-angle waist on both sides of the wedge-shaped glass in Design 2 is between 5° and 12°.

4. The device for detecting the refractive index of liquid based on a transmission light path according to claim 1, characterized in that: The laser light of the laser passes through four interfaces in sequence when passing through the sample cell; They are the interface between air and the outer wall of the glass pool wall on the laser incident side, the interface between the inner wall of the glass pool wall on the laser incident side and the liquid, the interface between the liquid and the inner wall of the glass pool wall on the laser exit side, and the interface between the outer wall of the glass pool wall on the laser exit side and the air; After the laser passes through the sample cell, the direction of the outgoing laser light path changes, and the variable of the direction change is related to the refractive index of the sample.

5. The device for detecting the refractive index of liquid based on a transmission light path according to claim 1, characterized in that: The sample cell is placed vertically or tilted, and the tilt angle is less than 10°, and the direction of the laser emission light path is changed.

6. The device for detecting the refractive index of liquid based on a transmission light path according to claim 1, characterized in that: The laser beam profile of the laser is circular, and the light spot projection is circular.

7. The device for detecting the refractive index of liquid based on a transmission light path according to claim 1, characterized in that: After the laser passes through the sample, its spot is imaged on the photoelectric imaging device, which can detect the position of the center point of the spot imaging with high precision. Since the laser is refracted after passing through the sample cell, the position of the spot imaging deviates from the direction of the incident laser. The refractive index of the sample is calculated based on the relationship between the position of the center point of the spot imaging and the refractive index. When the sample refractive index is in the range of 1.2 to 1.6, there is a linear relationship between the position of the center point of the light spot imaging and the refractive index.

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