CN110455745B - A method for measuring liquid refractive index dispersion and its application - Google Patents

Abstract

The invention discloses a method for measuring liquid refractive index dispersion and its application. In the present invention, a beam of monochromatic light is incident on the frosted side of the prism, after being scattered, it enters the prism and hits the interface between the bottom surface of the prism and the sample, and the light reflected by the interface exits through the other side of the prism to detect the outgoing light. The exit angle corresponding to the semi-shade field of view is formed by total reflection at the interface between the bottom surface of the prism and the sample; the exit angles under the standard sample and the sample to be tested are detected respectively, and the refractive index of the sample to be tested is calculated by substituting formula A. The method realizes the measurement of the refractive index dispersion of liquids when the refractive index of the prism is unknown; it can not only measure the refractive index dispersion of transparent liquids, but also measure the refractive index dispersion of weakly absorbing or scattering liquids; it is also suitable for measuring solids and thick films. And the refractive index dispersion of the gas; the measurement accuracy is high, reaching 0.0001 to 0.0003.

Description

A method for measuring liquid refractive index dispersion and its application

technical field

The invention belongs to the technical field of photoelectric precision measurement, and in particular relates to a method for measuring liquid refractive index dispersion and its application.

Background technique

Refractive index dispersion or spectroscopy refers to the phenomenon that a medium has different refractive indices for different wavelengths. The refractive index dispersion or spectrum measurement of liquids has important application significance. Through the measurement of liquid refractive index dispersion, the relationship between the refractive index and wavelength, concentration and composition of liquids can be known. The methods of measuring the refractive index of liquids mainly include: laser full Reflection method, optical fiber method, minimum deflection angle method, prism method, Abbe refractometer method, diffraction method, ellipsometry method, etc. In theory, these methods can be used for the measurement of liquid refractive index dispersion or spectrum, but there are still many difficulties in actual experimental measurement, such as the choice of light source, the placement of the liquid to be measured, and the detection method of the signal. The minimum deflection angle method is to put different liquids in a hollow prism, and measure the refractive index of the corresponding wavelength through the deflection of light of different wavelengths. This method requires a special hollow prism and measures a large amount of liquid; the Abbe refractometer method uses a critical At present, this method can only measure the refractive index of liquid with a wavelength of 589 nm, and is not suitable for measuring refractive index dispersion; the prism method is to add a liquid film between two equilateral triangular prisms. On the basis of the reflection principle, a prism is added to generate dispersion. This method requires three prisms. The experimental system is complicated to build, and the liquid film to be measured will produce interference fringes, resulting in a large measurement error, and the measurement accuracy of the refractive index can only be to three decimal places. Ellipsometry is mainly used for the measurement of the refractive index of solids or thin films, and can be used to measure the refractive index spectrum of liquids, but the spectroscopic ellipsometer used is expensive and complicated in data processing. When the liquid dispersion is directly measured, the liquid surface noise is relatively large. , the use of prisms to cooperate with the measurement will also bring problems such as cumbersome sample adjustment process and large errors. Therefore, there is an urgent need for a refractive index dispersion measurement method with simple operation, convenience and high measurement accuracy.

SUMMARY OF THE INVENTION

The primary purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, and to provide a method for measuring liquid refractive index dispersion.

Another object of the present invention is to provide an application of the above method for measuring the refractive index dispersion of a liquid.

To achieve the above object, the present invention is achieved through the following technical solutions:

A method for measuring liquid refractive index dispersion, comprising the steps of:

(1) A beam of monochromatic light is incident on the frosted side of the prism, and after being scattered, it enters the prism and hits the interface between the bottom surface of the prism and the sample. The light reflected by the interface exits through the other side of the prism, and the outgoing light is detected by The total reflection at the interface between the bottom surface of the prism and the sample forms the output angle corresponding to the semi-shadow field of view;

(2) by step (1), the exit angles under the standard sample and the sample to be tested are respectively detected, and the refractive index of the sample to be tested is calculated by substituting formula A;

(3) obtaining the refractive index and dispersion of the monochromatic light of the sample to be tested at different wavelengths through steps (1) and (2);

The formula A is:

Among them, n _2d (λ) is the refractive index of the sample to be measured, n ₂ (λ) is the refractive index of the standard sample, α is the bottom angle of the prism, Φ(λ), Φ _d (λ) are the measurement standard sample and the sample to be measured, respectively. When the outgoing light is totally reflected by the interface between the bottom surface of the prism and the sample, the outgoing angle corresponding to the semi-shadow field of view is formed.

The light entrance surface (working surface) of the prism described in step (1) is a frosted surface.

The prism described in the step (1) is preferably an isosceles prism; more preferably an isosceles prism with a base angle of 45° or 60°; most preferably a refractive index n ₁ =1.7450 or 1.5100, and a base angle of 45° or 60° ° isosceles prism.

The sample described in step (1) is preferably liquid, solid or thin film.

The standard sample described in step (2) is preferably a standard liquid or a liquid with a known refractive index.

The sample to be tested in step (2) is preferably a liquid, a solid or a thin film.

The process of measuring the liquid refractive index dispersion of the present invention is shown in Figure 1, and the details are as follows:

A beam of polychromatic light source passes through a monochromator, and sequentially selects monochromatic light of different wavelengths to enter the interface between the prism and the sample through the frosted side of the prism, and detects the exit angle corresponding to the semi-shade field of view of the outgoing light on the other side of the prism; respectively; By measuring the exit angle of the standard sample and the exit angle of the sample to be tested, the refractive index and dispersion of the sample to be tested under different wavelengths of monochromatic light are calculated according to formula A.

The principle analysis of the method of the present invention is as follows:

As shown in Figure 2, let λ be the wavelength of the incident beam, n _o , n ₁ (λ), and n ₂ (λ) are the refractive indices of air, prism, and standard liquid, respectively, and n ₂ (λ) is less than n ₁ ( λ), θ ₁ (λ), θ ₂ (λ), Φ(λ) are the incident angle and refraction angle of the interface between the bottom surface of the prism and the standard liquid when measuring the standard liquid, and the exit angle of the interface between the other side of the prism and the air. angle, α is the base angle of the prism, and the refractive index of air is n ₀ =1. According to the law of refraction of light, there are:

n ₁ (λ) sinθ ₁ (λ)=n ₂ (λ) sinθ ₂ (λ) (1)

When the incident angle gradually increases, total reflection occurs, with θ ₂ (λ)=90°:

From the triangular relationship and the law of refraction in Figure 2, when total reflection occurs, it is easy to obtain:

θ ₃ (λ)=|α-θ ₁ (λ)| (3)

n ₁ (λ) sinθ ₃ (λ)=n ₀ sinφ(λ) (4)

where θ ₃ (λ) is the incident angle of light on the AC surface when total reflection occurs.

According to the trigonometric formula, (3), (4) into (2) can be obtained:

Similarly, when measuring the liquid to be tested, let n _2d (λ) be the refractive index of the liquid to be tested, and n _2d (λ) is less than n ₁ (λ), θ _1d (λ), θ _2d (λ), Φ _d (λ) are the incident angle and refraction angle of the interface between the bottom surface of the prism and the liquid to be measured, and the exit angle of the interface between the other side of the prism and the air when measuring the liquid to be measured. According to the law of refraction of light, there are:

n ₁ (λ) sinθ _1d (λ)=n _2d (λ) sinθ _2d (λ) (6)

When the incident angle gradually increases, total reflection occurs, with θ _2d (λ)=90°:

n _2d (λ)=n ₁ (λ) sinθ _1d (λ) (7)

In the same way, for the liquid to be tested, we can get:

θ _3d (λ)=|α-θ _1d (λ)| (8)

n ₁ (λ) sinθ _3d (λ)=n ₀ sinφ _d (λ) (9)

where θ _3d (λ) is the incident angle of light on the AC surface when total reflection occurs.

According to the trigonometric relationship, substituting equations (5), (8), and (9) into equation (7) can be obtained,

It can be known from formula (10) that the refractive index n _2d (λ) of the liquid to be measured has nothing to do with the refractive index of the prism. If the dispersion n ₂ (λ) of the standard liquid and the base angle α of the prism are known, the refractive index dispersion or spectrum of the liquid to be measured can be calculated as long as the corresponding wavelengths of the standard liquid and the liquid to be measured are measured respectively.

In the process of measuring refractive index dispersion by the method of the present invention, after the experimental system is adjusted, the emission angles of a series of different wavelengths of a standard sample are measured once as known data for use. When measuring the refractive index dispersion of the unknown sample to be tested, the data can be directly called and substituted into formula (10) to calculate the refractive index dispersion of the sample to be tested.

The application of the method for measuring the refractive index dispersion of liquid in measuring the refractive index dispersion of a sample.

The samples include liquids, solids and films.

The standard sample is a liquid or standard liquid with known refractive index dispersion.

A device for measuring refractive index dispersion is designed and obtained by the above method, comprising a light source, a first convex lens, a monochromator, a second convex lens, an aperture diaphragm, a prism, a sample carrier, a rotating stage, an outer turntable, Telescope; along the direction of the light beam, the light source, the first convex lens, the monochromator, the second convex lens, the aperture diaphragm and the rotating stage are arranged in sequence, the rotating stage is arranged in the central area of the outer turntable, and the prism is located in the rotating stage. At the center of the rotation axis of the stage, the bottom surface of the prism is connected with a sample carrier for loading samples; the outer turntable is connected with the telescope and rotates synchronously, which is used for the observation and measurement of the semi-shade field of view of the outgoing beam. The outer turntable can read the position of the telescope. The telescope also has the function of self-collimation, which can calibrate its own angular position.

The light source is a polychromatic light source, preferably a continuous spectrum or discrete spectrum light source such as a xenon lamp, a tungsten halogen lamp, a mercury lamp, a sodium lamp and various lasers.

The first convex lens and the second convex lens are preferably quartz glass single lenses.

The monochromator is preferably a grating or prism monochromator, which can be selected to output monochromatic light of different wavelengths manually or automatically.

The wavelength resolution is preferably 2-10 nm.

The aperture diaphragm is preferably an adjustable diaphragm, and the semi-shade field of view contrast can be increased by manually adjusting the diaphragm size.

The prism is preferably an isosceles prism; more preferably an isosceles prism with a base angle of 45° or 60°; most preferably an isosceles prism with a refractive index n ₁ =1.7450 or 1.5100 and a base angle of 45° or 60° .

The sample carrier is preferably one of U-shaped groove, glass sheet with black tape, black frosted glass, black tape, and glass substrate with black tape.

The reading disc of the outer turntable has a dial with a range of 0° to 360°, and the accuracy of its rotation angle is 0.5°.

The outer turntable has two symmetrical angular verniers at a distance of 180°, and the minimum division is 1'.

The central area of the outer turntable is provided with an inner turntable.

The inner turntable and the rotating stage are preferably fixedly connected.

The telescope and the outer turntable are preferably fixedly connected. When the inner turntable is fixed, the telescope rotates through a certain angle, and the value of the rotation angle can be read from the cursor; when recording data, read the values shown by the two cursors, Take its average.

The telescope is composed of an objective lens, an Abbe eyepiece, and a reticle. The central axis of the object platform is adjusted to be perpendicular to the optical axis of the telescope by the self-collimation method, and its position can be calibrated and the angle value can be read by being fixed with the outer turntable.

The optical path adjustment process of the above device is as follows:

Place the light source, the first convex lens, the monochromator, the second convex lens and the aperture diaphragm on a straight line to make them coaxial, so that the bottom surface of the prism is located in the center of the rotation axis of the rotating stage, so that the light emitted by the light source passes through the first convex lens. Focus on the entrance slit of the monochromator, and the monochromatic light with a wavelength of λ emerges from the exit slit of the monochromator and enters the frosted side of the prism through the second convex lens and the aperture diaphragm. Angle, so that the parallel green light emitted by the small transparent cross line in the telescope through the objective lens is reflected by the exit surface of the prism and the small cross image coincides with the upper cross line in the eyepiece, and the rotating stage is fixed.

The specific measurement steps of the above device are as follows:

(1) Select the outgoing wavelength through the wavelength selection knob of the monochromator, and record the wavelength value;

(2) Measurement of the exit angle of the standard sample: place the standard sample on the sample carrier, adjust the telescope to observe the exit side of the prism, and see the half-shadow field of view formed by the total reflection of the interface between the bottom surface of the prism and the sample in the field of view of the telescope. The dividing line of the semi-shadow field of view is adjusted to the vertical alignment line in the eyepiece of the telescope. At this time, the values indicated by the two cursors are read out on the outer turntable, and the average position angle value a is obtained. Turn the telescope to align the exit side of the prism, so that The small cross image after the parallel green light emitted by the transparent small cross line through the objective lens and reflected by the prism exit side coincides with the upper cross wire in the eyepiece, record the value indicated by the two cursors on the outer turntable at this time, and average it to get Its position angle value b, the absolute value of the subtraction a-b of the two position angle values is the exit angle of the standard sample.

(3) Measurement of the exit angle of the sample to be tested: place the sample to be tested on the sample carrier, adjust the telescope to observe the exit side of the prism, and see the semi-shadow field of view formed by the total reflection of the interface between the bottom surface of the prism and the sample in the field of view of the telescope , adjust the dividing line of the semi-shade field of view to the vertical alignment line in the eyepiece of the telescope. At this time, read the values indicated by the two cursors on the outer turntable, and average them to obtain the position angle value c. Turn the telescope to align the exit side of the prism. , so that the small cross image of the parallel green light emitted by the transparent small cross line through the objective lens and reflected by the prism exit side coincides with the upper cross line in the eyepiece, and record the value indicated by the two cursors on the outer turntable at this time, and find The average position angle value d is obtained, and the absolute value of the subtraction c-d of the two position angle values is the exit angle of the sample to be tested.

(4) Calculation of the refractive index of the sample to be tested: Substitute the measured angle value into formula (10) to obtain the refractive index of the sample to be tested at the wavelength λ, change the wavelength of the incident light by a monochromator, and repeat the above steps to obtain the sample to be tested. Sample refractive index dispersion or spectrum.

Compared with the prior art, the present invention has the following advantages and effects:

1. The present invention can realize the measurement of liquid refractive index dispersion under the condition that the refractive index of the prism is unknown;

2. The present invention can measure not only the refractive index dispersion of transparent liquids, but also the refractive index dispersions of weakly absorbing or scattering liquids;

3. The present invention is also suitable for measuring the refractive index dispersion of solids, thicker (greater than 1 micron) films and gases;

4. The measurement accuracy of the present invention is high, and the measurement accuracy of the refractive index of the liquid is 0.0001-0.0003;

5. The measuring device of the present invention is simple, and the operation and measuring process are convenient.

Description of drawings

FIG. 1 is a flow chart of the measurement method of the present invention.

FIG. 2 is an optical path diagram of the measurement principle of the present invention.

FIG. 3 is a schematic diagram of a measuring device and an optical path according to Embodiment 1 of the present invention.

FIG. 4 is a schematic diagram of a measurement device and an optical path according to Embodiment 2 of the present invention.

FIG. 5 is a schematic diagram of a measurement device and an optical path according to Embodiment 3 of the present invention.

FIG. 6 is a schematic diagram of a measurement device and an optical path according to Embodiment 4 of the present invention.

7 is a graph of the refractive index dispersion curve of a 60% glucose solution in Example 2 of the present invention.

FIG. 8 is a graph of the refractive index dispersion curve of the cover glass in Example 3 of the present invention.

9 is a graph of the refractive index dispersion curve of the gelatin film in Example 4 of the present invention.

In Figures 3-6, 1- polychromatic light source, 2- first convex lens, 3- monochromator, 4- second convex lens, 5- pinhole diaphragm, 6- prism, 7- liquid sample, 8- U-shape Tank, 9-rotating stage, 10-outer turntable, 11-telescope, 12-black tape, 13-glass sheet, 14-matching liquid, 15-solid sample to be tested, 16-film sample, 17-glass substrate .

Detailed ways

The present invention will be described in further detail below with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1

A device for measuring liquid refractive index dispersion, as shown in Figure 3, includes a polychromatic light source 1, a first convex lens 2, a monochromator 3, a second convex lens 4, an aperture diaphragm 5, a prism 6, a liquid sample 7, U-shaped groove 8 , rotating stage 9 , outer turntable 10 , telescope 11 . Among them, along the direction of the light beam, the polychromatic light source 1, the first convex lens 2, the monochromator 3, the second convex lens 4, the aperture diaphragm 5 and the rotating stage 9 are arranged in sequence, and the rotating stage 9 is arranged outside In the central area of the turntable 10, the prism 6 is located at the center of the rotating shaft of the rotating stage 9, and the bottom surface of the prism 6 is connected with a U-shaped groove 8 for loading liquid; Shadow field observation and measurement. The outer turntable 10 can read the angle value of the position of the telescope 11 . The telescope 11 also has the function of self-collimation, which can calibrate its own angular position.

The polychromatic light source 1 is a continuous spectrum or discrete spectrum light source such as xenon lamp, tungsten halogen lamp, mercury lamp, sodium lamp and various lasers; the first convex lens 2 and the second convex lens 4 are quartz glass single lenses; the monochromator 3 is a grating or Prism monochromator, selects and outputs monochromatic light of different wavelengths manually or automatically, and its wavelength resolution is 2-10nm; Prism 6 is an isosceles prism or an equilateral prism, and a common prism with a base angle of 60 or 45° is preferred. , such as prism refraction n ₁ =1.7450 or 1.5100; the aperture diaphragm 5 is an adjustable diaphragm, which can be adjusted manually to increase the contrast of the semi-shadow field of view; the U-shaped groove 8 is an anti-seepage water groove; the reading of the outer turntable 10 The disc has a scale from 0° to 360°, and its rotation angle accuracy is 0.5°. The outer turntable 10 has an inner turntable. The angle vernier, the minimum division is 1', the inner turntable is fixedly connected with the rotating stage 9; the telescope 11 is fixedly connected with the outer turntable 10. When the inner turntable is fixed, if the telescope rotates through a certain angle, the value of the rotation angle can be read from the vernier. When recording data, read the values indicated by the two cursors and take the average value; the telescope 11 is composed of an objective lens, an Abbe eyepiece and a reticle, and the central axis of the object stage and the optical axis of the telescope are adjusted by the self-collimation method Vertical, fixedly connected to the outer turntable 10 to calibrate its own position and read the angle value.

The optical path adjustment process of the above device is as follows:

Put the polychromatic light source 1, the convex lens 2, the monochromator 3, the convex lens 4 and the aperture diaphragm 5 on a straight line to make them coaxial, so that the bottom surface of the prism 6 is located at the center of the rotation axis of the rotating stage 9, so that the polychromatic light source is 1 The outgoing light is focused by the convex lens 2 to the entrance slit of the monochromator 3, and the monochromatic light with the wavelength of λ comes out from the exit slit of the monochromator 3 and is incident on the frosted side of the prism through the convex lens 4 and the aperture diaphragm 5. Adjust the angles of the rotating stage 9 and the outer turntable 10 so that the small cross image of the parallel green light emitted by the small transparent cross line in the telescope 11 through the objective lens and reflected by the exit surface of the prism coincides with the upper cross wire in the eyepiece, and is fixed. Rotate stage 9.

The specific measurement steps of the above device are as follows:

(1) Select the outgoing wavelength through the monochromator 3 wavelength selection knob, and write down the wavelength value;

(2) Measurement of the exit angle of the standard liquid: pour the standard liquid into the U-shaped groove 8, adjust the telescope 11 to observe the exit side of the prism, and see the semi-shadow view formed by the total reflection of the interface between the bottom surface of the prism and the liquid in the field of view of the telescope Adjust the dividing line of the semi-shade field of view to the vertical alignment line in the eyepiece of the telescope. At this time, read the values indicated by the two cursors on the outer turntable 10, and average them to obtain the position angle value a. Turn the telescope 11 to align the prism. 6, so that the parallel green light emitted by the small transparent cross line through the objective lens is reflected by the prism exit side and the small cross image coincides with the upper cross line in the eyepiece, and record the two cursors on the outer turntable 10 at this time. The values shown are averaged to obtain the position angle value b, and the absolute value of the subtraction a-b of the two position angle values is the exit angle of the standard liquid.

(3) Measurement of the exit angle of the liquid to be measured: pour the liquid to be measured into the U-shaped groove 8, adjust the telescope 11 to observe the exit side of the prism, and see in the field of view of the telescope the half-reflection formed by the total reflection of the bottom surface of the prism and the liquid interface To shade the field of view, adjust the dividing line of the half-shade field of view to the vertical alignment line in the eyepiece of the telescope. At this time, read the values shown by the two cursors on the outer turntable 10, and average them to obtain the position angle value c. Turn the telescope 11 pairs On the exit side of the quasi-prism 6, the small cross image after the parallel green light emitted by the small transparent cross line through the objective lens is reflected by the exit side of the prism coincides with the upper cross line in the eyepiece. The values indicated by the cursors are averaged to obtain the position angle value d, and the absolute value of the subtraction c-d of the two position angle values is the exit angle of the liquid to be measured.

(4) Calculation of the refractive index of the liquid to be measured: Substitute the measured angle value into the formula (10) to obtain the refractive index of the liquid to be measured at the wavelength λ, change the wavelength of the incident light by a monochromator, and repeat the above steps to obtain the liquid to be measured. Liquid Refractive Index Dispersion or Spectroscopy.

Example 2

A device for measuring liquid refractive index dispersion, as shown in Figure 4, includes a polychromatic light source 1, a first convex lens 2, a monochromator 3, a second convex lens 4, an aperture stop 5, a prism 6, a liquid sample 7, Rotating stage 9 , outer turntable 10 , telescope 11 , black tape 12 , glass sheet 13 .

The difference between the device provided in this embodiment and the embodiment 1 is that the carrier of the liquid sample is different, that is, the glass sheet 13 affixed with the black tape 12 will replace the U-shaped groove 8 . A black tape 12 is attached to one side of the glass sheet 13 to prevent reversed back, and a small amount of liquid sample 7 is placed on the black tape and close to the bottom surface of the prism, and placed on the rotating stage 9 together with the prism. In this embodiment, black ground glass or ground glass coated with black can also be used as the carrier of the liquid sample to realize the measurement of dispersion of a small amount of liquid sample.

The device and method provided in this embodiment and the double prism method are used to measure the refractive index dispersion of 60% glucose solution, wherein the prism refractive index n ₁ =1.7450, the base angle α = 60°, and pure water is used as the standard liquid, the results are shown in the figure 7: It shows that the results obtained by the device and method provided in this embodiment are very close to the results obtained by the common double prism method.

Example 3

A device for measuring solid refractive index dispersion, as shown in Figure 5, includes a polychromatic light source 1, a first convex lens 2, a monochromator 3, a second convex lens 4, a small aperture diaphragm 5, a prism 6, and a rotating stage 9. The outer turntable 10, the telescope 11, the black tape 12, the matching liquid 14, and the solid sample 15 to be tested.

The difference between the device provided in this embodiment and Embodiment 1 is that the sample to be tested and its carrier are different, that is, the solid sample 15 to be tested replaces the liquid sample 7, the black tape 12 replaces the U-shaped groove 8, and the matching liquid 14 is added at the same time. One side of the solid sample 15 to be tested is affixed with black tape 12 to prevent back reflection, and the other side is dripped with a little matching liquid 14 with the same refractive index as the prism, and then close to the bottom surface of the prism to ensure that there are no air bubbles between the prism and the solid sample; the sample and the prism are placed together. on the rotating stage 9.

The device and method provided in this embodiment are used to measure the refractive index dispersion of a common cover glass, wherein the prism refractive index n ₁ =1.7450, the base angle α = 60°, and pure water is used as the standard liquid. The results are shown in FIG. 8 .

Example 4

A device for measuring the refractive index dispersion of thin films, as shown in Figure 6, includes a polychromatic light source 1, a first convex lens 2, a monochromator 3, a second convex lens 4, an aperture diaphragm 5, a prism 6, and a rotating stage 9. Outer turntable 10 , telescope 11 , black tape 12 , matching liquid 14 , film sample 16 , glass substrate 17 .

The difference between the device provided in this embodiment and Embodiment 1 is that the sample to be tested and its carrier are different, that is, the film sample 15 replaces the liquid sample 7, the glass substrate 17 with the black tape 12 replaces the U-shaped groove 8, and simultaneously adds Matching fluid 14. The film sample 16 to be tested is coated on one side of the glass substrate 17, the other side of the glass substrate 17 is pasted with black tape 12 to prevent back reflection, and the film surface is dripped with a little matching liquid 14 with the same refractive index as the prism, and then close to the bottom surface of the prism to ensure There are no air bubbles between the prism and the solid sample; the sample is placed on the rotating stage 9 together with the prism.

The device and method provided in this embodiment are used to measure the refractive index dispersion of the gelatin film sample on the glass surface, wherein the prism refractive index n ₁ =1.7450, the base angle α = 60°, and pure water is used as the standard liquid. The results are shown in FIG. 9 .

Comparative Example 1

In order to compare the measurement accuracy, a classical Abbe refractometer and the device and method provided in Example 2 were used to measure the refractive indices of distilled water and 5% glucose solution at a wavelength of 589 nm. The measurement results are shown in Table 1. The results show that the method of the present invention can measure the refractive index of liquid with an accuracy of 0.0001.

Table 1 Abbe refractometer and this method measure the refractive index results of distilled water and 5% glucose solution

In a word, the specific structure of the present invention is various, as long as a beam of monochromatic light is incident on the frosted side of the prism, the detected outgoing light is totally reflected by the interface between the bottom surface of the prism and the standard sample (sample to be tested) to form a semi-shadow view The device for measuring the refractive index of the sample to be measured and its dispersion according to the exit angle corresponding to the field all belong to the protection scope of the present application.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (5)

1. A method of measuring refractive index dispersion of a liquid, comprising the steps of:

(1) a beam of monochromatic light enters the frosted side surface of the prism, enters the prism after being scattered by the frosted side surface and enters the interface between the bottom surface of the prism and the sample, the light reflected by the interface is emitted through the other side surface of the prism, and the emergent light is detected to form an emergent angle corresponding to a half-shadow view field through the total reflection of the interface between the bottom surface of the prism and the sample;

(2) detecting the emergence angles of the standard sample and the sample to be detected respectively through the step (1), and substituting the emergence angles into a formula A to calculate the refractive index of the sample to be detected;

(3) obtaining the refractive index and the dispersion of the monochromatic light of the sample to be detected at different wavelengths through the step (1) and the step (2);

the formula A is as follows:

wherein n is_2d(lambda) is the refractive index of the sample to be measured, n₂(lambda) is the refractive index of the standard sample, alpha is the base angle of the prism, phi (lambda), phi_d(lambda) respectively forming an emergent angle corresponding to a half-shadow view field by total reflection of emergent light through the bottom surface of the prism and an interface of the sample when the standard sample and the sample to be measured are measured;

the prism in the step (1) is an isosceles prism;

and (2) the light inlet surface of the prism in the step (1) is a frosted surface.

2. The method of measuring refractive index dispersion of a liquid according to claim 1, wherein: the isosceles prism is an isosceles prism with a base angle of 45 degrees or 60 degrees.

3. The method of measuring refractive index dispersion of a liquid according to claim 2, wherein: the isosceles prism has a refractive index n₁An isosceles prism of 1.7450 or 1.5100.

4. The method of measuring refractive index dispersion of a liquid according to claim 1, wherein:

the standard sample in the step (2) is a standard liquid or a liquid with a known refractive index.

5. Use of the method of measuring refractive index dispersion of a liquid according to any one of claims 1 to 4 for measuring refractive index dispersion of a liquid sample.

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