JPS60201236A - Refractivity measuring element - Google Patents

Abstract

PURPOSE:To input a refractivity signal to another processing system in on-line system by detecting the position of a light beam refracted by a liquid sample by a line sensor. CONSTITUTION:A light beam from a laser source 1 is made incident slantly on a vessel 3 at an incident angle 45 deg.. Since front and rear surfaces of the wall of the vessel 3 are made parallel, the light beam is made incident on the sample from the direction parallel to that of the precedent incidence, refracted and received at the position P of the line sensor 2. If said beam is not refracted thereat, it advances along a dotted line and is received at a position P0. If the space between the incident surface of the vessel 3 and the sensor 2 is set to 30mm., a distance (d) between the positions P0 and P is indicated as a formula (n2: refractivity of sample). Since the output from the sensor 2 is an electric signal, it can be inputted to another processing system in on-line system.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention is directed to a novel refractive index measuring element used as the main part of a refracting needle for measuring the refractive index of a liquid.

(Background of the Invention) Conventionally, Atsube's refractometer has been the most popular refractometer for measuring the refractive index of liquids. Atsube's refractometer takes time to measure, and therefore cannot measure samples whose refractive index changes moment by moment.
There was a drawback that it was not possible to input information online.

(Objective of the Invention) Therefore, the present invention enables instantaneous measurement, continuous measurement over time, and online transmission of the measured refractive index or a parameter that has a certain functional relationship with the refractive index to another processing system. In order to obtain a refractometer that can input data, the present invention aims to provide a refractive index measuring element that can be called the heart of the refractometer.

(Summary of the invention) A light beam passing through the boundary surface of a substance with a refractive index of n + + nt (11+ @ ne ) is refracted at the boundary surface, and if the incident angle is θ7 and the exit angle is θ, then according to Snell's law, the following equation is obtained: :
n, S@θ, -Q, 關θ2...C formula l) holds true.

Now, the refractive index of the known substance is nl, and the refractive index of the liquid sample is nl.
, and the incident angle θ1 from the material side of n (where the critical angle is
If a light beam is incident on a sample at an angle θ, >0), the light beam is refracted as shown in FIG. 1 according to the refractive index n2 of the sample, and the incident angle θ.

ShiH Todorokasu output negative θ-, child's turtle-roaring surface (K)
The arrival position ff1(P) of the light beam on the parallel plane (K') having the distance CL) is the arrival position i11! when it is not refracted. (Th), and if the distance between them is (d), then as can be seen from Figure 1, d = ttan(θ2 - θ, n...
・c Equation 2) From Equations l and 2, nl, θ, and t
If is constant, then 1. It is expressed as a thickness f(d), and when d is measured, the refractive index n of the sample is immediately determined.

Therefore, we focused on line sensors as a device that can measure d instantaneously, so that it can be measured continuously over time, and that can be input online to another processing system.

Therefore, in the present invention, the incident angle θ with respect to the liquid sample.

(However, it is characterized by consisting of a light source (1) that enters a light beam at a critical angle〉θ,〉0) and a line sensor (2) that receives a light beam refracted by a liquid sample and detects the light receiving position. A refractive index measuring element is provided.

Hereinafter, the present invention will be specifically explained with reference to Examples.

(Example 1) FIG. 2 is an explanatory diagram of the refractive index measuring element on the other side of the main body.
1) is a laser light source with wavelength λ = 632.8 nm, (
2) 50 pieces per degree/steel line sensor, (3
) is a container made of glass with a refractive index n = 1.51, and (
S) is a liquid sample.

The light beam from the light source (1) enters the container (3) at an angle of incidence of 45°.
to make it obliquely incident. Since the front and back surfaces of the walls of the container N (3) are parallel, a light beam enters the sample (8) from a direction parallel to the original direction of incidence, is refracted, and passes through the line sensor (2).
The light is received at position @(P). If it were not refracted, the light would advance along the dotted line in FIG. 2 and be received at the position (Pa).

Distance t between the entrance surface of the container (3) and the line sensor (2)
When is 301111, the distance d between the 1st position (Po) and (P) is obtained from equations 1 and 2 as follows: d W 30Xtmn (45-5in-'-!!!!!
-! −)−−・−(Formula 3) (where n is the refractive index of the sample). Therefore, if an appropriate value of nR is substituted for the trial, the result will be as shown in Table 1 below.

Table 1 Here, a line sensor (2) with a resolution of 50 lines/fin is used, so #! According to Table 1, the refractive index measuring element of this example can measure the refractive index n with an accuracy of lXl0 near IJ51, and this accuracy is at the same level as the A, Be refractometer and Pulfrich refractometer. . In order to further improve accuracy, it is sufficient to lengthen the distance ML or increase the resolution of the line sensor.

There are various types of line sensors, but here we use one that generates currents M and In at terminals A and B when it receives light. This current Em, In is amplified by an amplifier (not shown), and then converted into a voltage V: by a calculator (not shown), and this voltage is displayed on a vt-tt pressure gauge (not shown). , the voltage V changes depending on the light receiving position (P).

Therefore, if the n-pressure V is measured in advance for several samples whose refractive index is known, the correlation between the voltage V and the refractive index can be known, so if the voltage V is measured for an unknown sample, the above The refractive index of the unknown sample is calculated from the correlation. If this calculating means is programmed into a microcomputer, the refractive index can be calculated instantly, so that according to the present invention, the refractive index can be measured instantly. Therefore, it is possible to remove the bottom of the glass container (3) and allow the sample to flow from top to bottom, even if the refractive index of the flowing sample changes moment by moment.
According to this device, the refractive index can be measured continuously.

Further, since the % voltage V has a constant functional relationship with the refractive index, the voltage V can be directly passed online to the next processing system as a parameter representing the refractive index.

In addition, if you find out the correlation between the voltages V and d in advance and program the equation for subtracting this relationship and n from Equation 3 into the microcomputer, you can directly obtain the refractive index n of the sample. I can do it.

To confirm the receiving position (P) when the light is not refracted, either insert a known sample with the same refractive index as the wall of the container (3) as the sample (8), or if it is troublesome, replace the sample. (8
) Instead, air may be introduced and the light receiving position (Pa) at that time may be used as the reference point. In this case, if the refractive index nm of air is known, the exit angle θa to the air can be calculated using the formula: ns−θ,5enasinθm−−−−−−′−(Equation 4
), the distance (da) between digits 412 (Po) and (Pa) is expressed by the formula: da wx L tan (θ, -θa)...
...Since it is calculated from C formula 5), the position (Po
) and (P) is the actually measured distance 1! (P) and (
Pad) is obtained as the sum of the distance (d) and the distance (da) calculated from (Equation 5), and by substituting this value (d) into Equation 3, the refractive index of the unknown sample (8) (n,) can be known.

(actual other side 2) FIG. 3 is an explanatory diagram of the refractive index measuring element of this example.

Here, a white light source is used as the light source (1), and the light from this light source is made into parallel light by a parallel optical system (4), passed through an aperture (5), and turned into a light beam with a small cross-sectional diameter. ) The entire sample is incident on the sample (8). The prism (6) is an element for making the light beam obliquely incident on the sample +<S:).

If the light beam is not refracted, the light beam is received at the position (Po)K of the line sensor (2), and if it is refracted by the sample CB), the light beam is received at the position (P) Vck'i. In this example, if the prism (6) is removed, the light receiving position (Po) when the light is not refracted can be immediately known.

Note that since white light is used as the light source (1,), strictly speaking, the refractive index differs depending on the wavelength, so the light receiving position (P) does not become a point but becomes a blurry circle. Therefore, the exact refractive index for each wavelength is If desired, a wavelength selective filter, for example a colored glass filter, can be arranged in front of the line sensor (2), or a wavelength selective filter or a spectrometer can be arranged between the prism (6) and the light source (1). However, it is more advantageous to dispose a wavelength selection filter before the line sensor (2) to remove noise.

(Example 3) FIG. 4 is an explanatory diagram of the refractive index measuring element of this example, (1)
is a He-Ne laser light source, (7) is a single mode optical fiber that guides the light source light, and (6) is a prism for oblique incidence. (8) is a liquid sample, (3) is a glass container for containing the sample (S), and an image fiber (8) is installed on the light-receiving side of the container, so that the light-receiving position does not move. The refracted light is then guided out of the container (3) and then into the magnifying optical system (9). As a result, the light refracted by the sample (8) is received on the line sensor (2) with d magnified by, for example, seven times. Therefore, the accuracy of this embodiment is further improved.

Mixtures of water and ethanol in various proportions were prepared as samples, and the measured voltage VC was obtained in the same manner as in Example 1). FIG. 5 shows the relationship between the calculated refractive index and the theoretical refractive index (which has already been proven to agree with experimental results). In FIG. 5, the mark indicates the value of the actually measured voltage V, and the actual Is
is a graph drawn using the above C1ausius-Mo@aotti relational expression, where the left vertical axis shows the voltage V, the right vertical axis shows the refractive index n, and the horizontal axis shows the concentration in volume % of ethanol.

It can be seen from FIG. 5 that there is a linear functional relationship between the voltage V and the refractive index n. Therefore, for the unknown sample (S), U
By measuring the pressure V, the refractive index n can be found. Magnifying optical system (
If the magnification of 9) is increased, the accuracy of the -ffJ refractive index will be improved.

(Effects of the Invention) As described above, according to the present invention, the refractive index can be measured instantaneously and continuously, and since the output from the line sensor is an electrical signal, it can be input online to another processing system.

In addition, it can be measured on the spot (1nsltu). There are no moving parts. There are also advantages such as remote control.

Therefore, the refractive index measuring element of the present invention is not only a refractometer, but also a refractive index measuring element that can measure the temperature, concentration, etc. of a sample by changing the refractive index.
It is also applied to indicators, detectors, and sensors that monitor changes in pressure, etc., and these indicators and detectors are extremely useful in automated food and chemical manufacturing plants.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating how a general light beam is refracted. FIG. 2 is an explanatory diagram of a refractive index measuring element according to Example 1 of the present invention. FIG. 3 is an explanatory diagram of the same example 2. FIG. 4 is an explanatory diagram of the same example 3. FIG. 5 is a graph showing the relationship between the concentration change depending on the volume % of ethanol, the voltage V, and the refractive index n. [Explanation of symbols of main parts] 1... Light source 2... Line sensor 3... Glass container 4... Collimator lens 5...・Aperture 6... Prism 7... Optical fiber B... Image fiber 9... Magnifying optical system Figure 1 Figure 2 Figure 3 Procedure correction form ( 1! 1980 7ri! 2nd 1. 19 Ushi no Fist 6 1982 - Patent Application No. 57575 Relationship with Hangyu Patent Applicant 3-2-3 Marunouchi, Chiyoda-ku, Tokyo (411 ) Nihon Kogaku TJ Hayashi Obumi Company 4, Agent Address: 1-6-3-5 Nishi-Oi, Honbunagawa-ku, Tokyo 140, Column 6 of “Detailed Description of the Invention” of the specification to be amended, Contents of the amendment (1) “a = t tan(θ,
-θ□), f d = L (tanθ, -tan
θ2)”. (2) "Constant" in line 8 of page 3 is corrected to "known." (3) "Injected and refracted" on page 4, line 12,
It is refracted as if it were incident on r and is corrected as J. (4) r d = 30 X tan on the bottom line of page 4
(45-(gin-"Mimi L)]"). 2 (5) Table 1 on page 5 of the same page is corrected as shown in the attached sheet. IA-In (6) Line 10 of page 6 of the same page. Correct "v-πFK" to "■=-Toji". IA+IB (7) In the 13th line of page 6, after "changes." (8) Correct the "Light receiving position (P)" on page 7, line 15 of the same page to "Light receiving position (PO) J." (9) Add "Refractive index" on the bottom line of page 7 of the same page. naJ, r refractive index n
, correct it as J. (In, page 8, line 5, “d a==Ltan (θ1
−θ, )”, r da=4(tanθ1− tanθ
, )” is corrected. 011, page 9, line 3, ``And if it is not refracted'' is changed to ``And if it is not refracted because the refractive index of the prism (6) and the refractive index of the sample (S) are the same.'' correct. ``If there is a sample (S) and it is refracted'' on page 9, lines 4-5 of a, the refraction is due to the fact that the refractive index of the sample (S) is different from the refractive index of the prism (6). Correct it to ``In case''. (that's all)

Claims (1)

[Claims] Incident angle θ with respect to the liquid sample (where critical angle 〉θ 〉0
1. A refractive index measuring element comprising: a light source (1) which receives a light beam at a point 1); and a line sensor (2) which receives a light beam refracted by a liquid sample and detects the position of the light receiving position.