CN210119439U - Device for measuring liquid refractive index - Google Patents
Device for measuring liquid refractive index Download PDFInfo
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- CN210119439U CN210119439U CN201920952225.5U CN201920952225U CN210119439U CN 210119439 U CN210119439 U CN 210119439U CN 201920952225 U CN201920952225 U CN 201920952225U CN 210119439 U CN210119439 U CN 210119439U
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Abstract
The utility model discloses a measuring device of liquid refracting index, including the light source, the light source is used for sending parallel light beam, and the semi-transparent semi-reflecting mirror sets up on the light path, and the semi-transparent semi-reflecting mirror divides into first light beam and second light beam with the horizontal light beam that the light source sent, and first light beam shines at the liquid column that awaits measuring, forms the rainbow distribution of the liquid that awaits measuring after the scattering, and first linear array CCD is used for recording the rainbow distribution of the liquid that awaits measuring, and first linear array CCD and second linear array CCD all are connected with the computer; the second light beam irradiates on the plane mirror, irradiates on the standard liquid column after being reflected by the plane mirror, and forms rainbow distribution of the standard liquid after being scattered, and the second linear array CCD is used for recording the rainbow distribution of the standard liquid; the utility model discloses a parallel light beam shines standard liquid column and the liquid column that awaits measuring, and the parallel forms first-order rainbow respectively in standard liquid column and the liquid column department that awaits measuring, obtains the refracting index of the liquid that awaits measuring through the first-order rainbow analysis to standard liquid column and the liquid column department that awaits measuring, easily operation.
Description
Technical Field
The utility model belongs to the technical field of the optical measurement, in particular to measuring device of liquid refracting index.
Background
Among a plurality of optical parameters of a substance, the refractive index is very important, the properties of the substance such as purity, concentration, dispersion and the like can be known through the refractive index, and the refractive index is closely related to some parameters such as thermo-optic coefficient and the like; accurate measurement of refractive index is of great significance in industrial sectors such as chemical plants, pharmaceutical plants and food plants.
In the prior art, liquid refractive index measurement methods are various, and common methods include:
1. a laser irradiation method, wherein the refraction of the liquid and the reflection of the liquid surface layer are required when the refractive index is measured by the laser irradiation method; the specific measurement process is that a laser irradiates a glass plate horizontally placed in a sample pool at a certain angle, the distance between a plurality of light spots on a wall is measured, the incident angle can be obtained by utilizing geometric knowledge, and the data are substituted into a liquid refractive index calculation formula deduced by Snell's law and related geometric relations, so that the refractive index of the liquid can be obtained; the disadvantages are as follows: the central position of the light spot cannot be accurately determined, and the error of the measurement result is large;
2. a diffraction grating method, wherein laser, a diffraction grating and a cubic glass sample cell are required when the refractive index of the liquid is measured by the diffraction grating method; the specific operation process comprises the following steps: the laser beam generated by the laser is irradiated onto the diffraction grating close to the glass pool in a collimating way, and a zero-order diffraction beam spot and a first-order diffraction beam spot can be diffracted on the rear wall of the glass pool before the liquid to be measured is not added; after the liquid to be measured is added, the first-order diffraction beam irradiates another point of the back wall after being refracted by the liquid; marking the points on coordinate paper attached to the outer side of the cubic glass sample pool, determining the relation between the angle and the length by utilizing a first-order diffraction grating to follow a Bragg law, obtaining a calculation formula for obtaining the refractive index and the Bragg law according to the Snell law, and obtaining the required length by measurement or indirectly by utilizing a Pythagorean theorem to replace the angle in the formula so as to obtain the refractive index of the liquid; the disadvantages are as follows: the operation difficulty is extremely high;
3. the method comprises the following steps of measuring by using a Michelson interferometer, wherein the measuring idea is to measure the refractive index by measuring the optical path of light in a medium to be measured and then measuring the thickness of the medium to be measured; the method has the following defects: the method needs to search interference fringes, is complex to operate and is only suitable for solid objects to be measured with parallel upper and lower surfaces and uniform thickness;
4. the fiber grating measurement method comprises the steps of using a transversely folded asymmetric ultra-long period fiber grating as a core measurement device, firstly measuring the environmental temperature change of liquid to be measured by using a high-order resonance peak of the ultra-long period fiber grating, then measuring the common change of the temperature and the refractive index of the liquid by using a low-order resonance peak, and finally correcting the measurement result of the low-order resonance peak by using the temperature measurement result of the high-order resonance peak to realize the measurement of the refractive index of the liquid under different temperature conditions; the method has the following defects: the principle is complex and the cost is high.
SUMMERY OF THE UTILITY MODEL
To the technical problem who exists among the prior art, the utility model provides a measuring device of liquid refracting index to it is great to measure liquid refracting index result error among the solution prior art, and the operation is complicated and the higher technical problem of cost.
In order to achieve the above purpose, the utility model adopts the technical scheme that:
the utility model provides a measuring device of liquid refracting index, including light source, semi-transparent semi-reflecting mirror, the level crossing, the liquid column that awaits measuring, first linear array CCD, a computer, standard liquid column and second linear array CCD, the light source is used for sending parallel light beam, semi-transparent semi-reflecting mirror sets up on the light path, semi-transparent semi-reflecting mirror divides the horizontal light beam that the light source sent into first light beam and second light beam, first light beam shines at the liquid column that awaits measuring, form the rainbow distribution of the liquid that awaits measuring after the liquid column scattering that awaits measuring, first linear array CCD is used for keeping track of the first-order rainbow scattering intensity distribution of the liquid that awaits measuring; the second light beam irradiates on the plane mirror, irradiates on the standard liquid column after being reflected by the plane mirror, forms rainbow distribution of the standard liquid after being scattered by the standard liquid column, and the second linear array CCD is used for recording first-order rainbow scattering intensity distribution of the standard liquid; the diameter size of the liquid column to be measured is the same as that of the standard liquid column, and the standard liquid is liquid with a known refractive index; the first linear array CCD and the second linear array CCD are both connected with a computer.
Further, the light source, the semi-transparent semi-reflective mirror and the plane mirror are arranged in a collinear manner, the liquid column to be detected and the first linear array CCD are arranged on one side of the light source, and a connecting line of the liquid column to be detected and the first linear array CCD is parallel to a connecting line of the light source and the plane mirror; the standard liquid column and the second linear array CCD are arranged on the other side of the light source, and a connecting line of the standard liquid column and the second linear array CCD is parallel to a connecting line of the light source and the plane mirror.
The first catheter, the first bracket and the first injection pump are arranged on one side of the light source, and the second catheter, the second bracket and the second injection pump are arranged on the other side of the light source; one end of a first guide pipe is vertically fixed on a first support downwards, the other end of the first guide pipe is connected with a first injection pump, the first injection pump is used for injecting liquid to be detected into the first guide pipe, and the liquid to be detected forms a liquid column to be detected at a position 1mm away from a pipe orifice of the first guide pipe; one end of the second guide pipe is vertically fixed on the second support downwards, the other end of the second guide pipe is connected with a second injection pump, the second injection pump is used for injecting standard liquid into the second guide pipe, and the standard liquid forms a standard liquid column at a position 1mm away from the pipe orifice of the second guide pipe.
The semi-transparent and semi-reflective mirror is arranged on the first rotating support, and the plane mirror is arranged on the second rotating support; the rotating angle precision of the first rotating bracket and the second rotating bracket is 0.017 degrees.
The device further comprises a first slide rail, a second slide rail and a third slide rail which are parallel to each other, wherein the second slide rail is arranged on one side of the first slide rail, and the third slide rail is arranged on the other side of the first slide rail; the light source, the semi-transparent semi-reflective mirror and the plane mirror are sequentially arranged on the first slide rail; the liquid column to be measured and the first linear array CCD are arranged on the second slide rail in a sliding mode, and the standard liquid column and the second linear array CCD (8) are arranged on the third slide rail.
Further, the light source employs a He — Ne laser.
Further, the injection flow rate of the first injection pump and the second injection pump is set to be in the range of 0.1ml/h to 1600ml/h, and the minimum resolution is 0.1 ml/h.
Furthermore, the first linear array CCD and the second linear array CCD both adopt SG-14-01k80-00-R type linear array CCDs.
Compared with the prior art, the beneficial effects of the utility model are that:
the utility model provides a measuring device for the refractive index of liquid, which irradiates a standard liquid column and a liquid column to be measured through parallel light beams, forms a first-order rainbow at the standard liquid column and the liquid column to be measured in parallel respectively, and obtains the refractive index of the liquid to be measured through the analysis of the first-order rainbow at the standard liquid column and the liquid column to be measured; the utility model discloses measuring device is simple, easily operates, and measurement structure is accurate.
Furthermore, by arranging three parallel slide rails, the measurement angular widths of the first linear array CCD and the second linear array CCD are determined according to the distance between the liquid column to be measured or the standard liquid column and the first linear array CCD or the second linear array CCD lens, the measured scattering angle range is determined by utilizing the rotation angle and the angular width of the plane mirror, and the result is very accurate by utilizing a relative measurement method.
Furthermore, the injection speed of the liquid column to be tested and the injection speed of the standard liquid column are controlled by adopting the injection pump, and the standard liquid and the liquid to be tested respectively form stable liquid columns at the positions of 1mm of the pipe openings of the first guide pipe and the second guide pipe, so that the accuracy of the test result is ensured.
The utility model calculates the relatively accurate refractive index of the liquid to be measured by measuring the analytic relation between the ratio of the difference between the first-order rainbow peak angle position and the second-order Airy peak angle position of the liquid column formed by the standard liquid and the liquid to be measured and the refractive index; the measuring method of the utility model is simple and easy to operate and realize; the online measurement can be realized by adopting the characteristic of high sensitivity of an optical method and combining with calculation software. Filtering the cylindrical liquid column first-order rainbow scattering intensity distribution by using an empirical mode decomposition method, and extracting a complete Airy structure from a first-order rainbow scattering intensity signal; because the EMD analysis is always carried out in the space domain, the conversion and the inverse conversion of the space domain and the frequency domain are not needed, and the space deviation of signals is avoided.
Drawings
Fig. 1 is a schematic structural view of a device for measuring a refractive index of a liquid according to the present invention;
FIG. 2 is a schematic diagram of a method for measuring a refractive index of a liquid according to the present invention;
FIG. 3 is a schematic diagram of the reflection and refraction light path of the light beam on the cross section of the liquid column in the present invention;
fig. 4 is a graph showing the scattering intensity distribution of the cylindrical liquid column with the first-order rainbow according to the present invention, wherein the graph shows the relationship between the scattering angle and the scattering intensity;
fig. 5 is a diagram showing a scattering intensity distribution of a first-order rainbow of a cylindrical liquid column according to the present invention, wherein the diagram shows a relationship between a pixel unit and a scattering intensity;
fig. 6 is a schematic view of a measurable angular width structure of the linear array CCD lens of the present invention;
fig. 7 is the EMD analysis result of the first-order rainbow scattering intensity distribution diagram of the cylindrical liquid column of the present invention;
fig. 8 is the complete Airy structure in the first-order rainbow scattering intensity distribution of the cylindrical liquid column of the present invention.
The system comprises a light source 1, a semi-transparent semi-reflective mirror 2, a plane mirror 3, a liquid column to be measured 4, a first linear array CCD5, a computer 6, a standard liquid column 7, a second linear array CCD8, a first rotating support 9, a second rotating support 10, a first sliding rail 11, a second sliding rail 12 and a third sliding rail 13, wherein the first sliding rail is a first sliding rail; 101 a first beam, 102 a second beam; 41 a first catheter, 42 a first stent, 43 a first syringe pump; 71 second conduit, 72 second bracket, 73 second syringe pump.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Referring to fig. 1 and 2, the utility model provides a liquid refractive index's measuring device, including light source 1, semi-transparent semi-reflecting mirror 2, level crossing 3, the liquid column 4 that awaits measuring, first linear array CCD5, computer 6, standard liquid column 7, second linear array CCD8, first runing rest 9, second runing rest 10, first slide rail 11, second slide rail 12 and third slide rail 13.
The light source 1 adopts a laser, and the light source 1 is used for emitting parallel light beams; the semi-transparent semi-reflecting mirror 2 is arranged on a light path of the parallel light beams, the semi-transparent semi-reflecting mirror 2 divides the parallel light beams emitted by the light source 1 into a first light beam 101 and a second light beam 102, the first light beam 101 irradiates on the liquid column 4 to be detected, and rainbow distribution of the liquid to be detected is formed after the first light beam is scattered by the liquid column 4 to be detected; the first linear array CCD5 is used for recording the first-order rainbow scattering intensity distribution of the liquid to be measured; the second light beam 102 is reflected by the plane mirror 3 and then irradiates on the standard liquid column 7, rainbow distribution of the standard liquid is formed after the second light beam is scattered by the standard liquid column 7, the standard liquid column 7 is formed by the standard liquid with known refractive index and wavelength, and the second linear array CCD8 is used for recording first-order rainbow scattering intensity distribution of the standard liquid; the first linear CCD5 and the second linear CCD8 are both connected to the computer 6.
The light source 1, the semi-transparent semi-reflective mirror 2 and the plane mirror 3 are arranged in a collinear way, the liquid column 4 to be detected and the first linear array CCD5 are arranged at one side of the light source 1, and the connecting line of the liquid column 4 to be detected and the first linear array CCD5 is parallel to the connecting line of the light source 1 and the plane mirror 3; the standard liquid column 7 and the second linear array CCD8 are arranged on the other side of the light source 1, and the connecting line of the standard liquid column 7 and the second linear array CCD8 is parallel to the connecting line of the light source (1) and the plane mirror 3.
The first slide rail 11, the second slide rail 12 and the third slide rail 13 are arranged in parallel, the second slide rail 12 is arranged on one side of the first slide rail 11, and the third slide rail 13 is arranged on the other side of the first slide rail 11; the light source 1 is arranged on a first slide rail 11 in a sliding way through a bracket, the semi-transparent and semi-reflective mirror 2 is arranged on the first slide rail 11 in a sliding way through a first rotating bracket 9, and the plane mirror 3 is arranged on the first slide rail 11 in a sliding way through a second rotating bracket 10; the first bracket 42 is arranged on the second slide rail 12 in a sliding manner, and the first linear array CCD5 is arranged on the second slide rail 12 in a sliding manner; the second bracket 72 is slidably disposed on the third slide rail 13, and the second linear array CCD8 is slidably disposed on the third slide rail 13.
One end of the first conduit 41 is vertically fixed on the first bracket 42 downwards, and the other end of the first conduit 41 is connected with the first injection pump 43; the first injection pump 43 is used for injecting the liquid to be measured into the first conduit 42, and the liquid to be measured forms a stable liquid column 4 to be measured at a position 1mm away from the orifice of the first conduit 41; one end of the second conduit 71 is vertically fixed on the second bracket 72 downwards, and the other end of the second conduit 71 is connected with the second injection pump 73; the second injection pump 73 is used for injecting standard liquid into the second conduit 71, and the standard liquid forms a stable standard liquid column 7 at the position 1mm away from the orifice of the second conduit 71; the first guide pipe 41 and the second guide pipe 71 are both circular guide pipes, the circular guide pipes are the same in size, and the diameter sizes of the formed liquid column to be measured 4 and the standard liquid column 7 are the same.
The measurement principle is as follows:
referring to fig. 3, fig. 3 is a schematic view showing a cross section of a liquid column formed by flowing out a liquid from a circular conduit; after the liquid flows out through the circular conduit, a cylindrical liquid column is formed, and the radius of the cylindrical liquid column is assumed to be R, and the refractive index is assumed to be m;
irradiating the cylindrical liquid column by adopting parallel incident light with the wavelength of lambda, wherein the parallel incident light comprises light rays 1 and light rays 2, the emergent light rays 1 'of the light rays 1 after being reflected by the primary inner surface of the cylindrical liquid column, and the included angle between the emergent light rays 1' and the irradiation direction of the parallel incident light is theta; according to the geometrical optical characteristics, the included angle theta has a minimum value, and the minimum value of the included angle theta is called a geometrical optical rainbow angle; the size of the geometric optical rainbow angle is only related to the refractive index m of the liquid to be measured.
For a liquid column with radius R of a monochromatic plane wave incident on, a rainbow formed by emergent rays after undergoing one-time inner surface reflection is called a first-order rainbow, and a certain intensity distribution exists near a geometrical optical rainbow angle, and the intensity distribution can be represented by first-order rainbow scattering intensity.
Referring to fig. 4, a graph of a relation between a first-order rainbow scattering intensity distribution and a scattering angle of a cylindrical liquid column includes an Airy structure formed by interference of emergent light rays reflected by an inner surface of the cylindrical liquid column after parallel light rays near a first-order rainbow geometric optical angle are subjected to primary reflection, and a Ripple structure formed by interference of emergent light rays reflected by a direct reflected light on a surface of the cylindrical liquid column and the emergent light rays reflected by the inner surface of the cylindrical liquid column after the parallel light rays are subjected to primary reflection.
According to the Airy theory of the cylindrical liquid column first-order rainbow scattering intensity distribution, the first-order Airy peak angle position theta in the cylindrical liquid column first-order rainbow scattering intensity distribution1The mathematical expression of (a) is:
wherein, thetargA first order rainbow geometric optical angle;
α is a dimensionless dimension parameter,
h is the curvature of the rainbow cubic wavefront,
second-order Airy peak angle position theta in cylindrical liquid column first-order rainbow scattering intensity distribution2The mathematical expression of (a) is:
the mathematical expression for the difference Δ θ between the primary and secondary Airy peak angle positions is:
Δθ＝θ2-θ1＝2.816627·h13·α-23(3)。
as can be seen from the above equations (1) to (3), the difference Δ θ between the primary and secondary Airy peak angle positions is affected by the liquid refractive index m and the diameter D; therefore, the liquid refractive index m is inverted by utilizing the difference delta theta between the peak angle positions of the primary Airy and the secondary Airy;
setting two cylindrical liquid columns with the diameters of D of a standard liquid column and a liquid column to be detected, measuring the primary Airy peak angle position and the secondary Airy peak angle position of the standard liquid column, and obtaining the difference delta theta between the primary Airy peak angle position and the secondary Airy peak angle position of the standard liquid column1(ii) a Measuring the primary Airy peak angle position and the secondary Airy peak angle position of the liquid column to be measured to obtain the difference delta theta between the primary Airy peak angle position and the secondary Airy peak angle position of the liquid column to be measured2Since the diameters of the standard liquid column and the liquid column to be measured are both D, when Delta theta1And Δ θ2The quotient eliminates the effect of the diameter.
Delta theta of different standard liquid columns1Delta theta with the liquid column to be measured2The ratio of (a) to (b) is different, but when the liquid column to be measured is determined, the delta theta of the liquid column to be measured1Delta theta with standard liquid column2The ratio of (a) is uniquely determined.
Assuming a standard liquid column of Δ θ1Delta theta with the liquid column to be measured2The ratio of (c) is denoted as k, and thus the mathematical expression for k is:
therefore, when the respective primary and secondary Airy peak angle positions of the standard liquid and the liquid to be measured are obtained through measurement, the difference delta theta between the primary and secondary Airy peak angle positions of the standard liquid column is respectively obtained through calculation1And the difference delta theta between the primary and secondary Airy peak angle positions of the liquid column to be measured2(ii) a According to Δ θ1And Δ θ2Calculated to obtain the Delta theta of the standard liquid column1Delta theta with the liquid column to be measured2Obtaining the refractive index m of the liquid column to be detected according to the ratio k, wherein the inversion formula of the refractive index m of the liquid column to be detected is as follows;
wherein h is0Is the standard liquid column rainbow third wave front curvature,
m0is the refractive index of a standard liquid column;
and then, solving an equation by utilizing the matlab to directly obtain the refractive index m of the liquid column to be detected.
The result of the first-order rainbow scattering intensity distribution of the cylindrical liquid column measured by the linear array CCD is the relation between the corresponding pixel unit and the scattering intensity, and is shown in the attached figure 5; therefore, the pixel unit of the linear array CCD in the result needs to be angle-calibrated to obtain the relationship between the scattering angle and the scattering intensity, as shown in fig. 4.
When the pixel units of the linear array CCD are angle-calibrated, referring to fig. 6, according to the geometric relationship, the scattering angle at the center of the linear array CCD pixel is the angle between the semi-transparent semi-reflective mirror or the plane mirror and the base line
Twice as much, the base line is perpendicular to the parallel beam,
the rotation angle of the semi-transparent semi-reflecting mirror or the plane mirror; the measurable angular width of the linear array CCD lens determined by the distance between the cylindrical liquid column and the linear array CCD pixel plane is
After the linear array CCD pixel unit is subjected to angle calibration, the obtained scattering angle range is
According to the result of the angle calibration of the linear array CCD pixel units, the first-order rainbow scattering intensity distribution is converted from the relationship between the corresponding pixel units and the scattering intensity into the relationship between the scattering angle and the scattering intensity, as shown in fig. 4.
Referring to fig. 4, since the relation graph of the scattering intensity distribution and the scattering angle of the first-order rainbow of the cylindrical liquid column includes a Ripple structure, the first-order Airy peak angle position of the first-order rainbow of the cylindrical liquid column cannot be directly measured.
The utility model discloses in utilize Empirical Mode Decomposition (EMP) to filter the first-order rainbow scattered intensity signal of liquid column, extract complete Airy structure from first-order rainbow scattered intensity signal.
The EMD is a scale separation algorithm, adopts the EMD to extract a complete Airy structure from a first-order rainbow scattering intensity signal, and comprises the following steps:
s1, determining all extreme points of an original rainbow sequence I (theta), constructing an upper envelope u (theta) consisting of the extreme points and a lower envelope v (theta) consisting of the minimum points by using a cubic spline curve, and calculating an upper envelope mean sequence and a lower envelope mean sequence, wherein the mathematical expression of the upper envelope mean sequence and the lower envelope mean sequence is as follows:
s2, calculating a difference sequence q (theta) of the original rainbow sequence I (theta) and the mean sequence p (theta) by using the original rainbow sequence I (theta) and the mean sequence p (theta), wherein the mathematical expression of the difference sequence q (theta) is as follows:
q(θ)＝I(θ)-p(θ) (8)；
s3, judging whether the difference sequence q (theta) satisfies the following conditions: a) the number of the extreme points is equal to the number of the zero crossing points or is different from the zero crossing points by one at most; b) the mean value of upper and lower envelope lines at any point q (theta) is 0;
s4, if the Q (theta) is satisfied, the Q (theta) is a decomposed first high-frequency mode IMF 1;
s5, if the mean value sequence of the upper envelope line and the lower envelope line is not satisfied, repeatedly taking the mean value sequence of the upper envelope line and the lower envelope line, and calculating the difference value sequence until the difference value sequence satisfies the stop condition, wherein the difference value sequence satisfying the stop condition is a decomposed first high-frequency mode IMF 1;
s6, subtracting IMF1 from I (theta), and repeating the steps S1-S5 for the residual components until all modal sequences are separated, wherein the mathematical expression of the original rainbow sequence I (theta) is as follows:
therefore, the above equation (9) represents that the first-order rainbow scattering intensity signal is decomposed into the sum of n mode functions IMF (θ) and one residual component R (θ).
Referring to fig. 7 and 8, fig. 7 shows the EMD analysis result of the simulated rainbow signal, the first-order rainbow scattering intensity signal is formed by the superposition of several light rays after mutual interference, therefore, the EMD analysis of the first-order rainbow scattering intensity signal can be regarded as the inverse decomposition of the superposition, and therefore, the first IMF1 and the second IMF2 represent the components of the Ripple structure of the rainbow, the third IMF3 represents the components of the Airy structure of the rainbow, and the last item represents the average trend of the rainbow signal. Since the EMD is always performed in the spatial domain, the conversion and inverse conversion between the spatial domain and the frequency domain are not required, so that the spatial offset of the signal is avoided, and the difference between the first-order and second-order Airy peak angle positions of the cylindrical liquid column first-order rainbow can be obtained through the Airy structure component in the EMD result of the rainbow signal, as shown in fig. 8.
Utilize liquid refracting index measuring device, when carrying out the liquid refracting index, including following step:
the plane mirror 3 is rotated and moved and,ensuring that the second linear array CCD8 can just receive the first-order rainbow scattering intensity distribution of the standard liquid, and calculating to obtain the scattering angle range measured by the second linear array CCD8 as
Wherein the content of the first and second substances,
the rotation angle of the plane mirror 3 is an included angle between the plane mirror and a base line, and the base line is perpendicular to the parallel light beams;
the angular width of the lens of the second linear array CCD8 as measured,
determined by the distance between the center of the liquid column 4 to be measured and the first linear array CCD5
Δθ1＝2.816627·h0 1/3·α-2/3；
wherein h is0Is the standard liquid column rainbow third wave front curvature,
m0the refractive index of the liquid column to be measured;
α is a dimensionless dimension parameter;
extracting a complete Airy structure from the first-order rainbow scattering intensity distribution of the liquid to be detected to obtain the difference delta theta between the first-order and second-order Airy peak angle positions of the liquid column to be detected2，Δθ2The mathematical expression of (a) is:
Δθ2＝2.816627·h1 1/3·α-2/3；
wherein h is1Is the three-time wave front curvature of the liquid column rainbow to be measured,
m is the refractive index of the liquid column to be detected;
and 7, obtaining an inversion formula of the refractive index m of the liquid column to be detected according to the ratio k of the difference between the primary and secondary Airy peak angle positions in the standard liquid column and the Airy structure of the liquid column to be detected, wherein the inversion formula comprises the following steps:
and finally, solving an inversion formula of the refractive index m of the liquid column to be detected by using a matlab solution equation to obtain the refractive index m of the liquid column to be detected.
Examples
In the utility model, the first injection pump 43 is used for generating the liquid to be detected into the liquid column 4 to be detected, and the second injection pump 73 is used for generating the standard liquid into the standard liquid column 7; the parameters of first syringe pump 43 and second syringe pump 73 are selected as: the setting range of the injection flow rate is 0.1ml/h-1600 ml/h; the minimum resolution is 0.1 ml/h; the setting range of the total injection amount is 0.1ml-9999.9 ml; the using environment temperature of the injection pump is 5-43 ℃; the injection precision is +/-3%.
The inner diameter of a thin tube connected with an injector in the injection pump is 0.8mm, and the outer diameter is 1.6 mm.
The light source 1 adopts a He-Ne laser, the He-Ne laser adopts a model HNL150L laser produced by Soranbo company, the wavelength of parallel rays emitted by the laser is 632.8nm, the power is 15mW, and linearly polarized light is output.
The first linear array CCD5 is used for recording rainbow distribution of the liquid to be measured, and the second linear array CCD8 is used for recording rainbow distribution of the standard liquid; the first linear array CCD5 and the second linear array CCD8 both adopt high-speed linear array CCDs, and the parameters of the high-speed linear array CCDs are as follows: the picture element is 14 μm; the minimum acquisition rate is 300 frames/second and the maximum is 68000 frames/second, with 1024 data points per frame.
The utility model decomposes the rainbow signal by using the empirical mode decomposition technology, not only can obtain complete Airy component, but also has good denoising effect; three parallel slide rails are arranged, the measurement angular width of the linear array CCD is determined according to the distance between the center of the liquid column and the lens of the linear array CCD, and the scattering angular range is determined according to the rotation angle and the angular width of the plane mirror, so that the method has very accurate result by using a relative measurement method; the injection speed, namely the injection pressure, is controlled by using an injection pump, the liquid finally passes through a vertical thin tube, the inner diameter of the thin tube is determined, and a stable liquid column is formed at the position of 1mm of the tube opening.
The above description is only illustrative of the preferred embodiments of the present invention, and any variations, modifications, decorations, etc. may be made without departing from the principle of the present invention, and these variations, modifications, decorations, etc. are all considered to be within the scope of the present invention.
Claims (8)
1. The device for measuring the refractive index of the liquid is characterized by comprising a light source (1), a semi-transparent and semi-reflective mirror (2), a plane mirror (3), a liquid column to be measured (4), a first linear array CCD (5), a computer (6), a standard liquid column (7) and a second linear array CCD (8), wherein the light source (1) is used for emitting parallel light beams, the semi-transparent and semi-reflective mirror (2) is arranged on a light path, the semi-transparent and semi-reflective mirror (2) divides the horizontal light beams emitted by the light source (1) into a first light beam (101) and a second light beam (102), the first light beam (101) irradiates the liquid column to be measured (4), rainbow distribution of the liquid to be measured is formed after the first light beam is scattered by the liquid column to be measured (4), and the first linear array CCD (5) is used for recording first-; the second light beam (102) irradiates on the plane mirror (3), irradiates on the standard liquid column (7) after being reflected by the plane mirror (3), forms rainbow distribution of the standard liquid after being scattered by the standard liquid column (7), and the second linear array CCD (8) is used for recording first-order rainbow scattering intensity distribution of the standard liquid; the diameter of the liquid column (4) to be measured is the same as that of the standard liquid column (7), and the standard liquid is liquid with a known refractive index; the first linear array CCD (5) and the second linear array CCD (8) are both connected with the computer (6).
2. The device for measuring the refractive index of liquid according to claim 1, wherein the light source (1), the semi-transparent and semi-reflective mirror (2) and the plane mirror (3) are arranged collinearly, the liquid column (4) to be measured and the first linear array CCD (5) are arranged at one side of the light source (1), and a connecting line of the liquid column (4) to be measured and the first linear array CCD (5) is parallel to a connecting line of the light source (1) and the plane mirror (3); the standard liquid column (7) and the second linear array CCD (8) are arranged on the other side of the light source (1), and a connecting line of the standard liquid column (7) and the second linear array CCD (8) is parallel to a connecting line of the light source (1) and the plane mirror (3).
3. The device for measuring the refractive index of liquid according to claim 1, comprising a first conduit (41), a first bracket (42), a first injection pump (43), a second conduit (71), a second bracket (72) and a second injection pump (73), wherein the first conduit (41), the first bracket (42) and the first injection pump (43) are arranged on one side of the light source (1), and the second conduit (71), the second bracket (72) and the second injection pump (73) are arranged on the other side of the light source (1); one end of a first guide pipe (41) is vertically fixed on a first support (42) downwards, the other end of the first guide pipe (41) is connected with a first injection pump (43), the first injection pump (43) is used for injecting liquid to be detected into the first guide pipe (41), and the liquid to be detected forms a liquid column (4) to be detected at a position 1mm away from a pipe orifice of the first guide pipe (41); one end of a second conduit (71) is vertically fixed on a second bracket (72) downwards, the other end of the second conduit (71) is connected with a second injection pump (73), the second injection pump (73) is used for injecting standard liquid into the second conduit (71), and the standard liquid forms a standard liquid column at a position 1mm away from the orifice of the second conduit (71).
4. The device for measuring the refractive index of liquid according to claim 1, further comprising a first rotating support (9) and a second rotating support (10), wherein the half-mirror (2) is arranged on the first rotating support (9), and the plane mirror (3) is arranged on the second rotating support (10); the rotating angle precision of the first rotating bracket (9) and the second rotating bracket (10) is 0.017 degrees.
5. The device for measuring the refractive index of liquid according to claim 2, further comprising a first slide rail (11), a second slide rail (12) and a third slide rail (13) which are parallel to each other, wherein the second slide rail (12) is disposed on one side of the first slide rail (11), and the third slide rail (13) is disposed on the other side of the first slide rail (11); the light source (1), the semi-transparent semi-reflecting mirror (2) and the plane mirror (3) are sequentially arranged on the first sliding rail (11); the liquid column (4) to be measured and the first linear array CCD (5) are arranged on the second slide rail (12) in a sliding mode, and the standard liquid column (7) and the second linear array CCD (8) are arranged on the third slide rail (13).
6. The apparatus for measuring the refractive index of a liquid according to claim 1, wherein the light source (1) employs a He-Ne laser.
7. The apparatus for measuring refractive index of liquid according to claim 2, wherein the injection flow rate of the first syringe pump (43) and the second syringe pump (73) is set in a range of 0.1ml/h to 1600ml/h with a minimum resolution of 0.1 ml/h.
8. The apparatus for measuring the refractive index of a liquid according to claim 1, wherein the first linear CCD (5) and the second linear CCD (8) are both SG-14-01k80-00-R type linear CCD.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920952225.5U CN210119439U (en) | 2019-06-21 | 2019-06-21 | Device for measuring liquid refractive index |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920952225.5U CN210119439U (en) | 2019-06-21 | 2019-06-21 | Device for measuring liquid refractive index |
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| CN210119439U true CN210119439U (en) | 2020-02-28 |
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