CN215894388U - Solid-liquid medium refractive index measuring device - Google Patents
Solid-liquid medium refractive index measuring device Download PDFInfo
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- CN215894388U CN215894388U CN202121683312.9U CN202121683312U CN215894388U CN 215894388 U CN215894388 U CN 215894388U CN 202121683312 U CN202121683312 U CN 202121683312U CN 215894388 U CN215894388 U CN 215894388U
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Abstract
The utility model relates to the technical field of optical measurement, in particular to a device for measuring the refractive index of a solid-liquid medium. The device comprises a horizontal screw guide rail and a loading groove, wherein a semiconductor laser and an optical power sensor are respectively connected to two ends of the screw guide rail in a sliding manner, and the semiconductor laser and the optical power sensor are respectively driven by a stepping motor and move on the screw guide rail; still include first guide bar and second guide bar, the first guide bar one end of institute passes through hinged joint year thing groove, and the other end and semiconductor laser fixed connection, second guide bar one end passes through hinged joint year thing groove, the other end and optical power sensor fixed connection. The refractive index of the medium can be measured by the measuring device, the sample does not need to be damaged, secondary processing or treatment is carried out on the sample, and the compatible measurement of the solid medium and the liquid medium is realized.
Description
Technical Field
The utility model relates to the technical field of optical measurement, in particular to a device for measuring the refractive index of a solid-liquid medium.
Background
The refractive index is an important optical parameter of the medium and can reflect the characteristics of the concentration, purity and the like of the medium. The refractive index of the medium is accurately measured, and the method has important significance in the fields of teaching, scientific research and industrial production. At present, the conventional methods for measuring the refractive index mainly include: a minimum deflection angle method, a diffraction grating method, a michelson interferometer method, a fiber optic young's interference method, a CCD measurement method, a total reflection method, and the like. These methods all have the characteristics of simple and understandable principle and simple and feasible measuring equipment and operation method, but have limitations respectively. The accuracy of the measurement of the distance between the spots in the diffraction grating method limits the accuracy of the refractive index. The fiber Young's interference method uses fiber as coherent light source to realize Young's interference, which has high requirements on experimental operation and device stability, and can not be widely applied.
At present, a typical solid and liquid medium refractometer, an abbe refractometer, is a common one and is manufactured by utilizing the total reflection principle. The method mainly measures the refractive index of transparent or semitransparent liquid, and has the advantages of high measurement precision, simplicity in operation and the like. However, it also gradually exposes some disadvantages: manual checking and adjustment are needed before measurement, the reading is completely aimed by visual observation, and the measurement precision is different from person to person; the measuring range is limited, and the method is only suitable for liquid media with the refractive index of 1.300-1.720; the sampling and measurement of toxic, strong corrosive, volatile, easy water absorption and irritant odor liquid have the problems of inconvenient operation, large pollution, unstable observed phenomenon and the like.
For refractive index measurements of opaque solid media that do not meet the Abbe refractometer requirements, a spectrometer refractometer is typically used. The measurement principle is based on a minimum deviation angle method, a spectrometer is used for changing an incident angle, and the refractive index of a medium is obtained by utilizing the Brewster law. There are also inherent limitations to this traditional solid medium refractive index measurement scheme: the medium is required to be regular in shape, and angle measurement can be directly carried out; the minimum angle of interval measurement is 0.1 degree, so that only discontinuous measurement can be carried out; in the measuring process, because the gravity distribution of the angle measuring table is uneven, the angle measuring table is difficult to keep a horizontal state all the time, and the glass surface is difficult to be strictly vertical to a horizontal plane, the larger the distance between measuring instruments is, the larger the angle measuring error is; ambient veiling glare interference is also an important factor.
The essence of the common method for measuring the refractive index is an angle measurement method, and the problems of limited range, incompatibility of solid and liquid media, inconvenience in operation, environmental pollution and the like exist. The existing various measuring methods are mostly suitable for single solid medium or liquid medium, mostly realize refractive index measurement through angle measurement, need procedures such as sampling, and have complex operation and limited measuring range of instruments.
SUMMERY OF THE UTILITY MODEL
The technical problem to be solved by the utility model is as follows: a device for measuring the refractive index of a solid-liquid medium is provided. The refractive index measuring device can be used for compatible measurement of solid-liquid media. And the refractive index measurement range is wider, the measurement accuracy is high, the operation difficulty is small, and the operation process is lossless and has no contact.
According to the Brewster's law, when the incident angle is the Brewster's angle, the reflected light becomes vertical linear polarized light, and is perpendicular to the refracted light, and the reflected light intensity is the weakest. Therefore, the refractive index of the medium can be calculated by searching the corresponding Brewster angle when the light intensity is weakest.
The utility model combines the Brewster's law and the characteristics of a reflection light path to design the device. When Brewster's phenomenon is detected, the distance L between the upper light source and the light intensity measuring instrumentbAnd the height d of the light source from the lower objective table, substituting into the formula n = Lb/2d，
The refractive index of the medium to be measured can be obtained. So that the measurement of the refractive index is achieved indirectly by means of an accurate distance measurement. According to the measurement formula, the refractive index range can be theoretically unlimited, and the method can be used for measuring the refractive index of the liquid.
A solid-liquid medium refractive index measuring device comprises a horizontal screw guide rail and a loading groove, wherein a semiconductor laser and an optical power sensor are respectively connected to two ends of the screw guide rail in a sliding manner, and the semiconductor laser and the optical power sensor are respectively driven by a stepping motor to move on the screw guide rail; still include first guide bar and second guide bar, the first guide bar one end of institute passes through hinged joint year thing groove, and the other end and semiconductor laser fixed connection, second guide bar one end passes through hinged joint year thing groove, the other end and optical power sensor fixed connection.
The screw guide rail is a high-precision screw guide rail with the minimum graduation of threads being 1 mm/circle, and the length of the screw guide rail is 1.200 m. The refractive index measurement of all media with refractive indexes within 1.0000-2.6000 can be satisfied. When special high-refractive-index media are measured, the screw guide rail can be lengthened to meet the requirement. The stepping motor is matched with the screw rod, and the horizontal displacement of 0.005 mm/time can be achieved when the action is minimum, so that the precision is ensured sufficiently.
The vertical distance d between the screw guide rail and the loading groove is 20 cm.
The carrying groove is used for placing solid or liquid to be measured. The utility model meets the measurement requirements of solid and liquid media, expands the application range and is beneficial to the generalization of the measurement device. Sampling is not needed in the measuring process, and the toxic and harmful media can be measured in a non-contact manner without causing pollution and waste; for media with higher value, such as precious gemstones and jades, and precious metals, sampling is not needed in measurement, and damage is not caused.
When the device is used, a medium to be measured is fixed on the carrying groove; and the semiconductor laser and the optical power sensor are in place, and the semiconductor laser is started to irradiate the laser on the medium to be measured. The stepping motor drives the semiconductor laser and the optical power sensor to move towards two ends of the screw guide rail respectively at the same speed, and the first guide rod and the second guide rod ensure that the optical power sensor receives optical signals all the time and calculate the refractive index. And carrying out accurate measurement after rough measurement to find the lowest refractive index.
According to the utility model, by means of the stepping motor and the precise horizontal screw guide rail, the distance can be precisely controlled, the minimum displacement motion at each time can be precisely 0.005mm, the design height of the device is 20.0000cm, the equivalent angle resolution is 0.002 degrees, and the position data of the weakest light intensity can be precisely captured. The method is obviously superior to the traditional spectrometer method for measuring the refractive index (the angular resolution is 0.1 degrees), and improves the measurement precision by 50 times.
In the measuring process, the medium to be measured is required to be placed on an objective table, the surface is irradiated by laser, the light intensity data of reflected light is collected, and the refractive index can be calculated. The medium which has strong corrosivity and toxicity and is not suitable for destructive detection can be subjected to nondestructive detection, and sampling and contact are not required in the measuring process.
The utility model can measure the medium refractive index without destroying the sample and carrying out secondary processing or treatment on the sample, and realizes the compatible measurement of the solid and liquid media.
Drawings
FIG. 1 is a schematic view of the structure of the apparatus of the present invention.
FIG. 2 is a light path diagram of the device of the present invention.
Shown in the figure: the device comprises a screw guide rail 1, a carrying groove 2, a semiconductor laser 3, an optical power sensor 4, a first guide rod 5 and a second guide rod 6.
Detailed Description
For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of exemplary embodiments of the present application and does not limit the scope of the present application in any way. Like reference numerals refer to like elements throughout the specification. It should be noted that the expressions first, second, etc. in this specification are used only to distinguish one feature from another feature, and do not indicate any limitation on the features. In the drawings, the thickness, size, and shape of an object have been slightly exaggerated for convenience of explanation. The figures are purely diagrammatic and not drawn to scale. It will be further understood that the terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "including," and/or "containing," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
A solid-liquid medium refractive index measuring device comprises a horizontal screw guide rail 1 and a loading groove 2, wherein a semiconductor laser 3 and an optical power sensor 4 are respectively connected to two ends of the screw guide rail 1 in a sliding manner, and the semiconductor laser 3 and the optical power sensor 4 are respectively driven by a stepping motor and move on the screw guide rail; still include first guide bar 5 and second guide bar 6, 5 one end of first guide bar pass through hinged joint year thing groove 2, the other end and 3 fixed connection of semiconductor laser, 6 one end of second guide bar passes through hinged joint year thing groove 2, the other end and 4 fixed connection of light power sensor.
The vertical distance d between the screw guide rail and the loading groove is 20 cm.
The semiconductor laser can adjust the output optical power by changing the injection current of the semiconductor laser.
The optical power sensor is connected with the computer, so that the measured light intensity analog quantity can be fed back to the computer in time, light intensity data can be output, and smoothness and accuracy of the measuring process can be guaranteed.
The loading groove is used for fixing the medium to be measured and ensuring that the medium to be measured cannot move in the measuring process. The object carrying groove is connected with a first guide rod 5 and a second guide rod 6 through hinges, the first guide rod 5 is connected with the semiconductor laser 3, and the second guide rod 6 is connected with the optical power sensor 4. The first guide rod 5 ensures that the emitted laser always points to a medium to be measured, and the second guide rod 6 ensures that the light sensing surface of the optical power sensor 4 is always perpendicular to the reflected light to ensure the accuracy of light intensity data, and the structure is as shown in fig. 1.
The screw guide rail adopts a high-precision screw guide rail with the minimum thread graduation of 1 mm/circle, the length of the screw guide rail is 1.200m, and the refractive index measurement of all media with the refractive indexes within 1.0000-2.6000 is met. When a special high-refractive-index medium is measured, the screw guide rail can be lengthened to meet the requirement. The stepping motor is matched with the screw rod, and the horizontal displacement of 0.005 mm/time can be achieved when the action is minimum, so that the precision is ensured sufficiently.
The utility model also discloses a method for measuring the refractive index by using the measuring device, which comprises the following steps.
Fixing a medium to be detected on the carrying groove; the laser and the optical power probe are in place, and the laser is started to irradiate the medium surface to be measured.
Step motor drive semiconductor laser and light intensity sensor with the same speed respectively to the both ends of screw rod guide rail move, first guide bar and second guide bar guarantee that light power sensor receives the light signal all the time, gather the reverberation data, carry out the essence after the rough survey and survey. The intensity data of the reflected light is output on a computer.
During rough measurement, light intensity data are collected once at a large distance, fine measurement is carried out after the position interval of the weakest point of the light intensity is determined, and the light intensity data are collected once when the distance changes by 0.005mm each time and are stored in a computer. And after all data acquisition is finished, namely after the measurement is finished, connecting and drawing the accurate measurement data, and drawing a line drawing by taking the distance L between the semiconductor laser and the probe of the optical power sensor as an abscissa and the light intensity P of the reflected light as an ordinate.
Determining the distance L between the minimum light intensity P of the reflected light according to the measured databAnd calculating and outputting the refractive index of the medium to be detected.
After the light source irradiates the medium to be measured, the medium to be measured is reflected and refracted on the surface of the medium to be measured, and along with the change of the incident light irradiation angle, the propagation directions and the polarization states of refracted light and reflected light can be changed accordingly. The reflected light vibrates more than parallel-vibrating partially polarized light perpendicular to the incident plane, and the refracted light becomes partially polarized light vibrating more than perpendicular to the incident plane. When the incident angle is Brewster's angle, the reflected light becomes vertical linear polarized light and is vertical and orthogonal to the refracted light, and the light intensity of the reflected light is weakest at the moment. Angle of incidence, FIG. 2
（
Brewster's angle), the angle of refraction, the relationship between the refractive index of the medium and the refractive index of air is known from brewster's law:
the angle of the incident light is changed by adjusting the position of the laser semiconductor, so that the optical power sensor receives the reflected light and measures the light intensity of the reflected light. When the intensity of the reflected light is the weakest, the incident angle theta is the Brewster angle, i.e., the angle
. The geometric relationship is obtained by substituting the measured values Lb and d into equation (1):
the refractive index of the medium is:
and driving the two stepping motors to complete the adjustment of the distance between the semiconductor laser and the optical power sensor probe. The stepping angle of the stepping motor adopted by the utility model is 1.8 degrees, and the stepping motor can be divided into 200 sections when rotating for one circle. And the horizontal displacement of 0.005 mm/time can be achieved when the motion is minimum by matching with a high-precision horizontal spiral guide rail, and sufficient precision is ensured.
The optical power sensor can acquire data of the light intensity of the reflected light once after the stepping motor finishes moving every time, so that the accuracy of the weakest position of the light intensity is ensured.
The utility model requires that the stepping motor bearing the driving semiconductor laser and the stepping motor bearing the driving optical power sensor return to two sides above the medium to be measured before the measurement is started, and the horizontal distance between the stepping motor bearing the driving semiconductor laser and the stepping motor bearing the driving optical power sensor and the measuring point is 20 cm. After the measurement is started, the two motors respectively move towards the two sides at the same speed, stop at the same time after reaching the end point, and quickly return to the initial position for standby after the data processing is finished.
Claims (6)
1. The device for measuring the refractive index of the solid-liquid medium is characterized by comprising a horizontal screw guide rail and a loading groove, wherein a semiconductor laser and an optical power sensor are respectively connected to two ends of the screw guide rail in a sliding manner, and the semiconductor laser and the optical power sensor are respectively driven by a stepping motor and move on the screw guide rail; still include first guide bar and second guide bar, the first guide bar one end of institute passes through hinged joint year thing groove, and the other end and semiconductor laser fixed connection, second guide bar one end passes through hinged joint year thing groove, the other end and optical power sensor fixed connection.
2. The apparatus according to claim 1, wherein the screw guide has a minimum pitch of 1 mm/turn.
3. The apparatus for measuring refractive index of solid-liquid medium according to claim 1 or 2, wherein the length is 1.200 m.
4. The apparatus according to claim 1 or 2, wherein the screw guide is spaced from the loading groove by a vertical distance d of 20 cm.
5. The apparatus according to claim 1 or 2, wherein the optical power sensor is connected to a computer.
6. The apparatus for measuring refractive index of solid-liquid medium according to claim 1 or 2, wherein the first guide bar ensures that the laser emitted by the semiconductor laser always points to the medium to be measured, and the second guide bar ensures that the light sensing surface of the optical power sensor is always perpendicular to the reflected light.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121683312.9U CN215894388U (en) | 2021-07-23 | 2021-07-23 | Solid-liquid medium refractive index measuring device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121683312.9U CN215894388U (en) | 2021-07-23 | 2021-07-23 | Solid-liquid medium refractive index measuring device |
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| Publication Number | Publication Date |
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| CN215894388U true CN215894388U (en) | 2022-02-22 |
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| CN202121683312.9U Active CN215894388U (en) | 2021-07-23 | 2021-07-23 | Solid-liquid medium refractive index measuring device |
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- 2021-07-23 CN CN202121683312.9U patent/CN215894388U/en active Active
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