CN112304878A - Spectrophotometer optical fiber head assembly, photometer and method for measuring solution concentration - Google Patents
Spectrophotometer optical fiber head assembly, photometer and method for measuring solution concentration Download PDFInfo
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 120
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- 239000007788 liquid Substances 0.000 claims description 22
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- 230000003287 optical effect Effects 0.000 description 22
- 238000002835 absorbance Methods 0.000 description 19
- 238000001514 detection method Methods 0.000 description 18
- 230000008569 process Effects 0.000 description 6
- 235000013405 beer Nutrition 0.000 description 5
- 230000031700 light absorption Effects 0.000 description 4
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The invention discloses a spectrophotometer fiber head assembly, a photometer and a method for measuring solution concentration, which are mainly applied to the technical field of experimental instruments. The invention aims to provide a spectrophotometer fiber head assembly, a photometer and a method for measuring solution concentration, which effectively reduce mechanical errors and reduce measurement steps. The scheme is as follows: the spectrophotometer optical fiber head assembly comprises an optical fiber head insert and a first optical fiber head arranged on the insert, and further comprises a sliding support connected with the insert and a stepping motor used for driving the sliding support to do linear motion; the insert is connected with a soft sealing element which deforms along with the movement of the insert in a sealing manner, and the periphery of the sealing element is connected to a fixing plate of the photometer in a sealing manner through a sealing and pressing structure.
Description
Technical Field
The invention relates to a spectrophotometer fiber head assembly, a photometer and a method for measuring solution concentration, which are mainly applicable to the technical field of experimental instruments.
Background
At present, most of emission heads of micro spectrophotometers for experiments in the market are fixed based on a mounting plate and can not be independently adjusted, or are integrally adjusted along with the mounting plate.
In any structure, blank liquid (the blank liquid refers to a solution for dissolving a sample to be detected by a user, and the blank liquid does not contain a sample substance to be detected) detection is required, and an error caused by blank detection exists, so that an error of actual sample detection is caused, because the blank detection process may be caused by the source of the blank liquid, the preparation of the blank liquid, the storage time and temperature of the blank liquid, and the possibility of pollution on a measuring platform of an instrument.
For the mode that the emission head is integrally adjusted along with the installation plate, mechanical errors can be caused due to the installation precision of the structure, and mechanical zero point offset can be caused due to mechanical abrasion, oxidation and dirt on the mechanical positioning surface and the like caused by the fact that the position sensor is adopted to position the mechanical zero point along with the prolonging of the service time, so that the measurement precision cannot be guaranteed, and therefore the emission head has to be regularly calibrated.
Disclosure of Invention
In order to solve the technical problem, the invention provides a spectrophotometer fiber head assembly.
A second object of the present invention is to provide a spectrophotometer including the aforementioned fiber optic head assembly.
The third purpose of the invention is to provide a method for measuring the concentration of the solution by a spectrophotometer.
The technical scheme provided by the invention is as follows: the spectrophotometer optical fiber head assembly comprises an optical fiber head insert and a first optical fiber head arranged on the insert, and further comprises a sliding support connected with the insert and a stepping motor used for driving the sliding support to do linear motion; the insert is connected with a soft sealing element which deforms along with the movement of the insert in a sealing manner, and the periphery of the sealing element is connected to a fixing plate of the photometer in a sealing manner through a sealing and pressing structure. The sliding support is driven by the precise stepping motor, so that the first optical fiber head is driven to independently and precisely move, and compared with a mode that the emission head is integrally adjusted along with the mounting plate in the prior art, the structure is simplified, and mechanical errors caused by complex structure are avoided; meanwhile, the deformable sealing element is used for realizing the sealing connection between the insert and the fixing plate, so that the first optical fiber head is ensured to be always sealed in the moving process, and the influence on normal use caused by the fact that a solution permeates into the equipment is avoided.
Preferably, the sealing and compressing structure comprises an annular base, the upper end surface of the base is provided with an annular bulge, and an annular concave part is formed on the upper end surface of the base and the outer side of the annular bulge; the fixing plate presses the edge of the sealing element to the concave part to realize sealing. By utilizing the limiting function of the annular bulge, when the sealing element is sunken and deformed towards the lower part of the fixing plate, sufficient support and reverse action are provided; meanwhile, by utilizing the limiting function of the fixing plate, when the sealing element protrudes and deforms towards the upper part of the fixing plate, enough pressing force is provided; utilize this sealed compact structure can effectively guarantee the sealed when sealing member deformation.
Preferably, a groove is formed inside the annular protrusion, and the groove is used as a concave deformed accommodating cavity of the sealing element.
Preferably, a sliding rail shaft is mounted on the fixing plate, and a sliding rail bearing coaxially sleeved outside the sliding rail shaft is mounted on the sliding support. Guarantee the perpendicular high accuracy of first optical fiber head and remove, for the fan-shaped removal regulation of using the flap axle as the centre of a circle among the prior art, there is not the angular difference, improved the precision greatly.
A spectrophotometer comprises an upper measuring platform and a lower measuring platform which are oppositely arranged, wherein the lower measuring platform is provided with a spectrophotometer optical fiber head component as described above, the upper measuring platform is provided with an upper receiving optical fiber head and an upper transmitting optical fiber head which are connected through optical fibers, and the upper receiving optical fiber head is arranged opposite to a first optical fiber head of the optical fiber head component; and the lower measuring platform is provided with a lower receiving optical fiber head which is arranged right opposite to the upper transmitting optical fiber head.
Preferably, a placing groove is formed in the fixing plate and on one side of the optical fiber head assembly, and a support which can be hidden in the placing groove is mounted in the placing groove through a rotating shaft. When the device is used, the bracket is rotated to stand up, so that the phenomenon of shaking hands or misoperation of liquid dropping is prevented, and the liquid dropping is more efficient and accurate; when not in use, the utility model is laid down, and the hidden design does not affect the beauty.
A method of measuring solution concentration with a spectrophotometer, comprising:
s1: taking a solution to be measured, dripping the solution to be measured on a first optical fiber head of the optical fiber head assembly, pressing down an upper measuring platform to enable an upper receiving optical fiber head to be opposite to the first optical fiber head, and forming a liquid column between the upper receiving optical fiber head and the first optical fiber head;
s2: lighting a light source to obtain light intensity Ii in the current state; after the light source is lightened, light passes through a light path (a first optical fiber head, a solution to be detected, an upper receiving optical fiber head, an upper transmitting optical fiber head and a lower receiving optical fiber head) and is detected by a spectrometer in a photometer to obtain light intensity;
s3: the stepping motor drives the first optical fiber head to move a constant distance b upwards to receive the optical fiber head, and the light source is lightened to obtain light intensity I in the current statei+n(ii) a n is the number of times the stepper motor drives the first fiber head to move upwards from step S3;
s4: using formulas
Calculating the concentration of the solution to be detected; wherein c is the concentration of the solution to be measured, K is the molar absorption coefficient, b is the moving distance of the first optical fiber head relative to the upper receiving optical fiber head each time, n is the number of times of the stepper motor driving the first optical fiber head to move upwards from the step S3, and Ii+nIn order to start step S3 and drive the first optical fiber head to receive the light intensity after the optical fiber head moves for n times, Ii+n-1In order to drive the first optical fiber head to receive the light intensity after the optical fiber head moves for n-1 times by the stepping motor from the step S3, i is an integer greater than or equal to 0.
Preferably, the constant distance b is 0.01-0.1 mm.
Preferably, the method further comprises:
s5: and repeating the steps S3 and S4, taking the average value of a plurality of calculated results as the concentration of the solution to be measured, and further reducing the measurement error by using the average value.
Preferably, the step S101 is further included between the steps S1 and S2:
lighting a light source to obtain light intensity in the current state, if the light intensity is smaller than a set threshold value, determining that the solution to be detected is a high-concentration solution, moving a first optical fiber head to a set first position, and executing step S2; if the light intensity is greater than or equal to the set threshold, the light intensity is regarded as the light intensity Ii in step S2, and step S3 is performed.
The method comprises the steps that a light source is firstly lightened once before the solution to be measured is measured to obtain light intensity, whether the concentration of the solution is higher or lower can be judged according to the light intensity approximately, then a first optical fiber head is moved to an initial measuring point according to the value, different optical path measurement is adopted, proper absorbance is guaranteed to measure the concentration of the solution to be measured, and the situation that the absorbance is too high or too low in the measurement process cannot occur; the concentration range is judged in advance by independently moving the first optical fiber head, the concentration detection is realized within the optimal absorbance range, and the time is saved accurately. The method specifically comprises the following steps: the light absorption detection wavelength point of the solution to be detected by a user is input by the user, or a default value is used, when a first light source is lightened, the light intensity of the point is detected, if the light intensity of the point is lower than a set threshold value, the light absorption capability of the solution is very strong, the concentration of the solution is very high, and at this time, the measurement starting position is directly moved to the measurement zero point of the high-concentration solution (the fixed value is set through a system, namely if the high-concentration solution is judged, the optical path of a first optical fiber head and an upper receiving optical fiber head is correspondingly arranged).
Preferably, the step S1 is followed by the step of:
s101: lighting a light source to obtain light intensity in the current state;
s102: judging whether the current light intensity is smaller than a set threshold value, if so, determining that the solution to be detected is a high-concentration solution, moving a first optical fiber head stepper motor to drive the first optical fiber head to move 0.05-0.1mm upwards to receive the optical fiber head, and executing the step S101; if not, step S3 is executed with the light intensity as the light intensity Ii in step S2. And the automatic finding of the proper measurement zero point is continuously tried for many times, so that the automation degree is high.
Compared with the prior art, the invention has the following advantages:
1. the first optical fiber head in the optical fiber head assembly is driven by a stepping motor, the height of the first optical fiber head is independently and accurately adjusted, meanwhile, a soft sealing element which deforms along with the movement of the insert is connected to the insert in a sealing mode, and the periphery of the sealing element is connected to a fixing plate of a photometer in a sealing mode through a sealing and pressing structure. The sliding support is driven by the precise stepping motor, so that the first optical fiber head is driven to independently and precisely move, compared with the mode that the emission head is integrally adjusted along with the mounting plate in the prior art, the structure is simplified, mechanical errors caused by complex structure are avoided, compared with the fan-shaped movement adjustment in the prior art which takes the turnover plate shaft as the center of a circle, the angle difference does not exist, and the precision is greatly improved; meanwhile, the deformable sealing element is utilized to ensure that the first optical fiber head always keeps sealed in the moving process, and the solution is prevented from permeating into the equipment to influence normal use.
2. The invention changes the measuring optical path by moving the first optical fiber head for many times, the moving distance is constant every time, the same solution to be measured is measured for many times, the absorbance is calculated, and the concentration of the solution to be measured can be directly measured under the condition of not measuring the light intensity of the blank liquid (the principle is that the absorbance of the solution is in direct proportion to the optical path passing through the solution under the condition that the solution concentration is certain according to the Lambert beer law); the concentration of the solution to be detected can be detected by directly dropping the sample, so that the experimental steps are reduced, the concentration detection of the solution to be detected can be really completed by dropping one drop, the detection time is shortened, and the detection efficiency is improved. Meanwhile, the condition that errors are generated in actual sample detection due to errors generated in blank liquid testing is eliminated (the reason is that blank detection errors may be caused by the source of the blank liquid, the preparation of the blank liquid, the storage time and temperature of the blank liquid, possible pollution of a measuring platform of an instrument and the like in the blank detection process).
3. In actual measurement, the optical path is adjusted by a high-precision linear stepping motor, the motor moves to a position relative to a zero point in one measurement, the position is not an absolute zero point, the motor starts to move in the same direction for the same distance every time when the position relative to the zero point is measured, and the motor does not move in the opposite direction during the measurement, so that the accumulated error of the moving distance of the motor is almost eliminated, and the error of absorbance caused by the error of the optical path is eliminated.
4. The invention adopts relative zero point, and multi-section optical path measurement, and then the concentration is calculated according to the Lambert beer law, so that the problem that the measurement optical path is deviated after the instrument is used for a long time does not exist, namely the measurement optical path is not changed along with the increase of the service time of the instrument; compared with the prior art, the zero point is determined by the position sensor and the measuring arm moves by the contact between the mechanical structures, so that the problems that the zero point drift is caused and the measuring optical path is influenced due to abrasion, oxidation and dirt among structural members caused by long service time are solved.
5. The method comprises the steps that a light source is firstly lightened once before the solution to be measured is measured to obtain light intensity, whether the concentration of the solution is higher or lower can be judged according to the light intensity approximately, then a first optical fiber head is moved to an initial measuring point (measuring zero point) according to the value, different optical path measurement is adopted, proper absorbance is guaranteed to measure the concentration of the solution to be measured, and the situation that the absorbance is too high or too low in the measurement process cannot occur; through independently removing first optic fibre head, prejudge the concentration range, realize that concentration detection is in best absorbance range, accurate saving time has avoided because concentration is too high or low leading to the measuring inaccuracy excessively.
Drawings
FIG. 1 is a cross-sectional view of the spectrophotometer in accordance with the present invention.
FIG. 2 is a cross-sectional view of another perspective of the spectrophotometer of the present invention.
Fig. 3 is a block diagram of a fiber optic head assembly of the spectrophotometer of the present invention.
FIG. 4 is an enlarged view of the fiber optic head assembly of the present invention.
FIG. 5 is an enlarged view of another state of the fiber optic head assembly of the present invention.
FIG. 6 is a cross-sectional view of the annular base of the present invention.
Fig. 7 is a schematic structural view of a pipette holder provided on the spectrophotometer according to the present invention.
Reference numbers in the figures: an insert 1; a first fiber head 2; a sliding bracket 3; a stepping motor 4; a soft sealing member 5; a fixed plate 6; an annular base 7; an annular projection 8; a recessed portion 9; a groove 10; a sliding rail shaft 11; a sliding track bearing 12; an upper receiving optical fiber head 13; an upper emission optical fiber head 14; a lower receiving fiber stub 15; a placement groove 16; a bracket 17; a position sensor 18; the sensor senses the post 19.
Detailed Description
The invention is further described with reference to the following figures and detailed description.
As shown in fig. 1-6, a fiber head assembly of a spectrophotometer in this embodiment includes a fiber head insert 1 and a first fiber head 2 mounted on the insert, and the fiber head assembly further includes a sliding bracket 3 connected to the insert 1, and a stepping motor 4 for driving the sliding bracket 3 to perform linear motion; the sliding support 3 is driven by the precision stepping motor 4, so that the first optical fiber head 2 is driven to independently and precisely move, and compared with the mode that the emission head is integrally adjusted along with the mounting plate in the prior art, the structure is simplified, and mechanical errors caused by complex structure are avoided; compared with the sector movement adjustment taking the flap shaft as the circle center in the prior art, the angle difference does not exist, and the precision is greatly improved; the insert 1 is hermetically connected with a soft sealing element 5 which deforms along with the movement of the insert 1, and the periphery of the sealing element is hermetically connected to a fixing plate 6 of the photometer through a sealing and pressing structure; utilize deformable sealing member 5 to realize the sealing connection between mold insert 1 and the fixed plate 6, ensure that first optical fiber head 2 removes the in-process and keeps sealed with fixed plate 6 all the time, avoid inside solution infiltration equipment, influence normal use.
The sealing and compressing structure comprises an annular base 7, an annular bulge 8 is arranged on the upper end surface of the base, and an annular concave part 9 is formed on the upper end surface of the base 7 and the outer side of the annular bulge 8; the fixing plate 6 compresses the edge of the sealing element 5 to the concave part 9 to realize sealing, and after the sealing element 5 is installed, the cross section of the edge part of the sealing element 5 is step-shaped, so that the sealing effect is further ensured. By utilizing the limiting function of the annular bulge 8, when the sealing element 5 is concavely deformed towards the lower part of the fixing plate 6 (as shown in a state of figure 5), sufficient support and reverse action are provided; meanwhile, by utilizing the limiting function of the fixing plate 6, when the sealing element 5 is convexly deformed towards the upper part of the fixing plate 6 (as shown in the state of figure 4), enough pressing force is provided; utilize this sealed compact structure can effectively guarantee the sealed when sealing member 5 deformation, increase of service life.
A groove 10 is formed on the inner side of the annular protrusion 8 and serves as a containing cavity for the sunken deformation (as shown in the state of fig. 5) of the sealing element 5, so that the interference generated during the deformation is avoided.
The fixed plate 6 is provided with a sliding track shaft 11, and the sliding support 3 is provided with a sliding track bearing 12 which is coaxially sleeved outside the sliding track shaft. Utilize two high accuracy slip track axles 11, cooperation slip track bearing 12 combined mechanism, guarantee the perpendicular high accuracy of first optical fiber head 2 and remove, for the fan-shaped removal regulation of using the flap axle as the centre of a circle among the prior art, there is not the angular difference, improved the precision greatly.
As shown in fig. 1 and fig. 2, a spectrophotometer of this embodiment includes an upper measuring platform and a lower measuring platform which are oppositely disposed, the lower measuring platform is provided with a spectrophotometer fiber head assembly as described above, the upper measuring platform is provided with an upper receiving fiber head 13 and an upper emitting fiber head 14 which are connected by an optical fiber, wherein the upper receiving fiber head 13 is arranged opposite to the first fiber head 2; and a lower receiving optical fiber head 15 which is arranged opposite to the upper transmitting optical fiber head 14 is arranged on the lower measuring platform to form a loop.
As shown in fig. 7, a placing groove 16 is formed on the fixing plate 6 and on one side of the fiber head assembly, and a bracket 17 capable of being hidden in the placing groove is installed in the placing groove through a rotating shaft. When in use, the bracket 17 is rotated to stand up the bottle, so that the shaking of hands or the misoperation of liquid dropping is prevented, and the liquid dropping is more efficient and accurate; when not in use, the utility model is laid down and embedded into the placing groove 16, and the hidden design does not affect the appearance.
A position sensor 18 which can move along with the sliding support 3 is arranged on the sliding support 3, and a sensor induction column 19 matched with the position sensor 18 is arranged on the fixed plate 6. Each time of measurement, the first optical fiber head 2 moves for a certain stroke, after the measurement is completed, the first optical fiber head needs to return to a mechanical zero point for the next measurement, and the position sensor 18 is matched with the sensor induction column 19 to ensure that the first optical fiber head 2 returns to the mechanical zero point.
The method for measuring the concentration of a solution by a spectrophotometer of the embodiment comprises the following steps:
s1: taking a solution to be measured, dripping the solution to be measured on a first optical fiber head 2 of the optical fiber head assembly, pressing down an upper measuring platform to enable an upper receiving optical fiber head 13 to be opposite to the first optical fiber head 2, and forming a liquid column between the upper receiving optical fiber head and the upper receiving optical fiber head, wherein two ends of the liquid column are respectively contacted with the first optical fiber head 2 and the upper receiving optical fiber head 13;
s2: the light source is lightened to obtain the light intensity I under the current statei；
S3: the stepping motor drives the first optical fiber head 2 to move a constant distance b upwards to receive the optical fiber head 13, and the light source is lightened to obtain light intensity I in the current statei+n(ii) a n is the number of times the stepper motor drives the first fiber stub 2 to move upward from step S3;
s4: using formulas
Calculating the concentration of the solution to be detected; wherein c is the concentration of the solution to be measured, K is the molar absorption coefficient, b is the moving distance of the first optical fiber head 2 relative to the upper receiving optical fiber head 13, n is the number of times that the stepper motor drives the first optical fiber head 2 to move upwards from the step S3, and Ii+nTo receive the light intensity after the optical fiber head 13 moves up n times by driving the first optical fiber head 2 with the stepping motor from step S3, Ii+n-1In order to drive the first fiber head 2 to receive the light intensity n-1 times after the fiber head 13 is moved upward by the stepping motor from step S3, i is an integer greater than or equal to 0.
The value of the constant distance b is 0.01-0.1 mm.
The invention changes the measuring optical path by moving the first optical fiber head 2 for many times, the moving distance is constant every time, the same solution to be measured is measured for many times, the absorbance is calculated, the concentration of the solution to be measured can be directly measured under the condition of not testing the light intensity of the blank liquid, the concentration of the solution to be measured can be detected by directly dropping a sample, the experimental steps are reduced, the concentration detection of the solution to be measured can be really completed by dropping one drop, the detection time is reduced, and the detection efficiency is improved. The specific principle is as follows:
lambert beer's law:
a is absorbance; k is molar absorptivity; b is the thickness of the absorption layer; c is the concentration of the light absorbing species;
from the law, it can be known that when the concentration of the light absorbing substance is constant, the absorbance a is proportional to the thickness b of the absorbing layer, and when the absorbance a and the thickness b of the absorbing layer are known, the concentration of the light absorbing substance can be calculated.
The optical path is measured by moving the first optical fiber head 2 for multiple times, the moving distance is constant every time, the optical path is gradually reduced, and the optical path is in direct proportion to the absorbance when the solution concentration is constant according to the Lambert beer law;
the light intensity under the first measurement optical path is recorded as I1The stepping motor drives the first optical fiber head 2 to move upwards to receive the optical fiber head 13 by a constant distance b, and then the second light intensity is measured as I2Since the optical path is shifted from large to small, the light intensity I2Can be regarded as light intensity I1Incident light intensity of (I)1Is I2The light intensity of the emergent light passing through the constant distance b can be known by the Lambert beer law
After the absorbance a is calculated, the concentration c of the solution to be measured can be calculated by formula a ═ Kbc, where b is the constant distance that the stepper motor drives the first fiber head 2 to move upward the receiving fiber head 13. The principle is as follows: b is the displacement of the first optical fiber head 2, if the absorbance of the section of the liquid column with the reduced optical path is calculated, I is1As I2The emergent light intensity passing through the constant distance b; since the solution concentration does not change due to the change in the optical path length (change in the height of the liquid column), the calculated solution concentration matches the actual solution concentration.
Theoretically, the concentration of the solution to be measured can be calculated by detecting the light intensity twice, but in order to improve the calculation accuracy and accuracy, the movement measurement needs to be performed for multiple times, that is, the steps S3 and S4 are repeated, and the average value of multiple calculated results is taken as the concentration of the solution to be measured.
In order to save time, the step S101 between the steps S1 and S2 of the present invention further includes:
lighting a light source to obtain the light intensity in the current state, if the light intensity is smaller than a set threshold value, considering that the solution to be detected is a high-concentration solution, moving the first optical fiber head 2 to a set first position, and executing the step S2; if the light intensity is greater than or equal to the set threshold, the light intensity is regarded as the light intensity Ii in step S2, and step S3 is performed.
That is, the light source is firstly lighted up once before the solution to be measured is measured to obtain the light intensity, whether the concentration of the solution is higher or lower can be roughly judged according to the light intensity, then the first optical fiber head 2 is moved to an initial measuring point according to the value, different optical path measurement is adopted, the proper absorbance is ensured to measure the concentration of the solution to be measured, and the condition that the absorbance is too high or too low during measurement can not occur; the concentration range is judged in advance by independently moving the first optical fiber head, the concentration detection is realized within the optimal absorbance range, and the time is saved accurately.
In order to save time and improve the automation degree, the step S1 further includes:
s101: lighting a light source to obtain light intensity in the current state;
s102: judging whether the current light intensity is smaller than a set threshold value, if so, determining that the solution to be detected is a high-concentration solution, moving a first optical fiber head stepper motor to drive the first optical fiber head to move 0.05-0.1mm upwards to receive the optical fiber head, and executing the step S101; if not, step S3 is executed with the light intensity as the light intensity Ii in step S2. And the automatic finding of the proper measurement zero point is continuously tried for many times, so that the automation degree is high.
The light intensity described in this embodiment may be the actual light intensity, or may not characterize the actual light intensity. When the light intensity does not represent the intensity of the actual light, specifically: the light is coupled to a spectrometer module of a photometer through a light path, is projected onto a linear CCD array after being split by a grating, the linear CCD array converts a received optical signal into an analog signal, converts the analog signal into a digital signal after being subjected to A/D conversion, and compares the digital signal with the set threshold value. The light absorption detection wavelength point of the solution to be detected is input by a user, or a default value is used, when a first light source is lightened, the light intensity of the point is detected, if the light intensity of the point is lower than a set threshold 1000 (the maximum 65535, the intensity of actual light is not represented), the light absorption capability of the solution is very strong, the concentration of the solution is very high, and at this time, the measurement starting position is directly moved to the measurement zero point of the high-concentration solution (the fixed value is set through a system, namely if the high-concentration solution is judged, the optical path of a first optical fiber head and an upper receiving optical fiber head is correspondingly arranged).
Claims (10)
1. The utility model provides a spectrophotometer fiber optic head subassembly, includes fiber optic head mold insert (1) and installs first fiber optic head (2) on this mold insert, its characterized in that: the optical fiber head assembly also comprises a sliding support (3) connected with the insert (1) and a stepping motor (4) used for driving the sliding support (3) to do linear motion; the insert (1) is connected with a soft sealing element (5) which deforms along with the movement of the insert (1) in a sealing manner, and the periphery of the sealing element is connected to a fixing plate (6) of the photometer in a sealing manner through a sealing and pressing structure.
2. The spectrophotometer fiber optic head assembly of claim 1, wherein: the sealing and compressing structure comprises an annular base (7), an annular bulge (8) is arranged on the upper end surface of the base, and an annular concave part (9) is formed on the upper end surface of the base (7) and the outer side of the annular bulge (8); the fixing plate (6) presses the edge of the sealing element (5) to the concave part (9) to realize sealing.
3. The spectrophotometer fiber optic head assembly of claim 2, wherein: a groove (10) is formed on the inner side of the annular bulge (8) and is used as a containing cavity for the sunken deformation of the sealing element (5).
4. The spectrophotometer fiber optic head assembly of claim 1, wherein: a sliding track shaft (11) is installed on the fixing plate (6), and a sliding track bearing (12) which is coaxially sleeved outside the sliding track shaft (11) is installed on the sliding support (3).
5. The utility model provides a spectrophotometer, includes relative last measuring platform and lower measuring platform who sets up which characterized in that: the spectrophotometer optical fiber head assembly as claimed in any one of claims 1 to 4 is mounted on the lower measuring platform, an upper receiving optical fiber head (13) and an upper transmitting optical fiber head (14) which are connected through optical fibers are mounted on the upper measuring platform, wherein the upper receiving optical fiber head (13) is arranged opposite to the first optical fiber head (2); and a lower receiving optical fiber head (15) which is arranged opposite to the upper transmitting optical fiber head (14) is arranged on the lower measuring platform.
6. The spectrophotometer of claim 5, wherein: a placing groove (16) is formed in the fixing plate (6) and on one side of the optical fiber head assembly, and a support (17) capable of being hidden in the placing groove is installed in the placing groove through a rotating shaft.
7. A method of measuring a concentration of a solution with a spectrophotometer, comprising:
s1: taking a solution to be measured, dripping the solution on a first optical fiber head (2), pressing down an upper measuring platform to enable an upper receiving optical fiber head (13) to be opposite to the first optical fiber head (2), and forming a liquid column between the upper receiving optical fiber head and the first optical fiber head;
s2: the light source is lightened to obtain the light intensity I under the current statei；
S3: the stepping motor drives the first optical fiber head (2) to upwards receive the optical fiber head (13) to move a constant distance b, and the light source is lightened to obtain light intensity I in the current statei+n；
S4: using formulas
Calculating the concentration of the solution to be detected; wherein c is the concentration of the solution to be detected, K is the molar absorption coefficient, b is the moving distance of the first optical fiber head (2) relative to the upper receiving optical fiber head (13) each time, n is the number of times that the stepping motor drives the first optical fiber head (2) to move upwards from the step S3, and Ii+nIn order to drive the first optical fiber head (2) to receive the light intensity of the optical fiber head (13) moving for n times by the stepping motor from the step S3, i is an integer greater than or equal to 0.
8. The method of measuring solution concentration by a spectrophotometer of claim 7, further comprising:
s5: and repeating the steps S3 and S4, and taking the average value of a plurality of calculated results as the concentration of the solution to be detected.
9. The method of measuring solution concentration by spectrophotometer according to claim 7, further comprising steps S101 between steps S1 and S2:
lighting a light source to obtain the light intensity in the current state, if the light intensity is smaller than a set threshold value, considering that the solution to be detected is a high-concentration solution, moving a first optical fiber head (2) to a set first position, and executing step S2; if the light intensity is greater than or equal to the set threshold, the light intensity is regarded as I in step S2iStep S3 is executed.
10. The method of measuring solution concentration with spectrophotometer according to claim 7, wherein step S1 is further followed by:
s101: lighting a light source to obtain light intensity in the current state;
s102: judging whether the current light intensity is smaller than a set threshold value, if so, determining that the solution to be detected is a high-concentration solution, moving a first optical fiber head (2) to drive a stepping motor of the first optical fiber head (2) to move 0.05-0.1mm upwards to receive the optical fiber head (13), and executing the step S101; if not, the light intensity is taken as I in step S2iStep S3 is executed.
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