CN110927112A - Method for measuring liquid refractive index by using Newton ring - Google Patents

Method for measuring liquid refractive index by using Newton ring Download PDF

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Publication number
CN110927112A
CN110927112A CN201911264013.9A CN201911264013A CN110927112A CN 110927112 A CN110927112 A CN 110927112A CN 201911264013 A CN201911264013 A CN 201911264013A CN 110927112 A CN110927112 A CN 110927112A
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plano
convex lens
cylindrical container
liquid
air bag
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李娟�
胡再国
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Sichuan University
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Sichuan University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/061—Sources
    • G01N2201/06113—Coherent sources; lasers

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
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  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

A method for measuring the refractive index of a liquid by using Newton' S rings relates to the measurement of the refractive index, comprising a plano-convex lens and a cylindrical container, the spherical center of the plano-convex lens contacts the center of the inner bottom surface of the cylindrical container, the diameter of the 1 st-order dark fringe and the diameters d1 and d11 of the 11 th-order dark fringe are measured, the central dark spot is assumed to be 0 grade, and S1= (d11/2) is calculated2‑(d1/2)2(ii) a Filling liquid between the plano-convex lens and the bottom surface of the inner side of the cylindrical container; the diameter of the 1 st order dark grain and the diameters d1 and d11 of the 11 th order dark grain were measured again, the central dark spot was rated as 0, and Sn = (d11/2) was calculated2‑(d1/2)2The refractive index of the liquid n = S1/Sn. The measuring principle of Newton's ring is clear; the amount of liquid required is relatively small; the measuring principle is simple, the operation is simple and convenient, and the measurement is rapid.

Description

Method for measuring liquid refractive index by using Newton ring
Technical Field
The invention relates to the measurement of refractive index, in particular to the measurement of the refractive index of liquid by means of the Newton's Ring principle.
Background
The Newton ring experiment is mainly used for measuring the spherical curvature radius of the plano-convex lens; the spherical curvature radius of the existing plano-convex lens is about 4 meters, and the diameter of the plano-convex lens is 6-10 cm; the newton rings were observed by a reading microscope, and the diameters of the newton rings were measured by the principle of a micrometer screw.
Disclosure of Invention
The invention measures the refractive index of a liquid by means of the principle of Newton's rings.
The invention adopts the technical scheme that the purpose of the invention is realized by: the method for measuring the liquid refractive index by utilizing the Newton's ring comprises a plano-convex lens and a cylindrical container, wherein the central part of the plano-convex lens is a spherical surface, and the spherical surface center of the plano-convex lens is contacted with the center of the bottom surface of the inner side of the cylindrical container, and the method is characterized in that: the edge of the plano-convex lens is an equal-thickness circular ring; cylindrical containerThe edge of the inner side of the device is a circular platform, and the circular ring with the same thickness at the edge of the plano-convex lens is placed on the circular platform; the equal-thickness circular ring at the edge of the plano-convex lens is in close contact with the circular platform to play a role in sealing and fixing; the diameter of the level 1 dark streak and the diameters d1 and d11 of the level 11 dark streak were measured, the central dark spot was assumed to be level 0, and S1= (d11/2) was calculated2-(d1/2)2(ii) a The left side of the inner side wall of the cylindrical container and the right side of the inner side wall are both provided with a groove, the left groove is communicated with a water inlet pipe, and liquid is injected into the water inlet pipe; the right groove of the cylindrical container is connected with an air bag, a pipeline connected with the air bag is provided with two air valves, the lower air valve is closed, the upper air valve is opened, the air bag is extruded, so that the air inside the air bag is discharged from the upper air valve, and the upper air valve is closed, namely the upper air valve can communicate or separate the air inside the air bag and the air outside the air bag; opening the lower end air valve, wherein the air bag has elasticity, and the elastic expansion of the air bag causes the liquid in the water inlet pipe to flow through a gap between the plano-convex lens and the inner bottom surface of the cylindrical container, even if the space between the plano-convex lens and the inner bottom surface of the cylindrical container is filled with the liquid; the diameter of the 1 st order dark grain and the diameters d1 and d11 of the 11 th order dark grain were measured again, the central dark spot was rated as 0, and Sn = (d11/2) was calculated2-(d1/2)2The refractive index of the liquid n = S1/Sn.
The invention has the beneficial effects that: the measuring principle of Newton's ring is clear; the distance between the plano-convex lens and the upper surface of the flat crystal is relatively small, so that the required liquid amount is relatively small; by means of the air bag, liquid can be sucked into a gap between the plano-convex lens and the upper surface of the flat crystal or the liquid between the plano-convex lens and the upper surface of the flat crystal is blown away; the measuring principle is simple, the operation is simple and convenient, and the measurement is rapid.
Drawings
FIG. 1 is a schematic view of a cylindrical container; FIG. 2 is a schematic view of a plano-convex lens; FIG. 3 is a view showing a positional relationship between a cylindrical container and a plano-convex lens; FIG. 4 is a schematic diagram of the optical path formed by Newton's rings; FIG. 5 is a view showing the structure of the apparatus;
wherein, 1, a plano-convex lens; 2. a cylindrical container; 3. a circular ring with equal thickness; 4. spherical surface; 5. a groove; 6. a water inlet pipe; 7. an air bag; 8. an air valve; 9. a circular platform.
Detailed Description
The principle is as shown in FIG. 4:
the difference △ =2 n d + lambda/2 between the light refracted at the A point and the light reflected from the bottom surface of the container, wherein n is the refractive index of the medium, and the condition of the Newton's ring dark fringe is △ = (2 k + 1) × lambda/2 (k =0,1,2,3,4 … …), and the r is the geometric relationshipk 2+(R-d)2=R2(ii) a Because R is>>d, so d = rk 2/(2R)；2*n*d+λ/2=2*n* rk 2/(2R) + λ/2= (2 k + 1) × λ/2; so rk 2= kλR /n ；rk+m 2=(k+m)λR /n ；rk+m 2- rk 2= m λ R/n. R for measuring m air spacesk+mAnd rkCalculating S1= rk+m 2- rk 2(ii) a Where the refractive index of air is 1.00027 (20 degrees celsius, one standard atmosphere) and is approximately 1. Then, the liquid is injected, and the r of m pieces at intervals is measuredk+mAnd rkCalculating Sn = rk+m 2- rk 2(ii) a Therefore, Sn/S1= [ m λ R/n]/[ mλR]= 1/n; i.e. n = S1/Sn.
The curvature radius R of the prior plano-convex lens is about 4m, and the diameter RkThe maximum value of (a) is 3-5 cm; the maximum value of d is therefore 0.3 mm; therefore, the gap between the plano-convex lens and the flat crystal is small, because the liquid has surface tension, it is easier to fill the plano-convex lens and the flat crystal with the liquid by means of the surface tension of the liquid, but to remove the liquid in the gap, air blowing is needed to complete: it is necessary to seal and then form a passage for gas (or liquid) from the left side to the right side.
Example (b):
the method for measuring the liquid refractive index by utilizing the Newton ring comprises a plano-convex lens 1 and a plane crystal, wherein the center of the plano-convex lens 1 is contacted with the upper surface of the plane crystal, and the method is characterized in that: the edge of the plano-convex lens 1 is an equal-thickness circular ring 3, and the central part of the plano-convex lens 1 is a spherical surface 4; the flat crystal is improved into a cylindrical container 2, the edge of the inner side of the cylindrical container 2 is a circular platform 9, and a circular ring 3 with the same thickness at the edge of a plano-convex lens 1 is placed on the circleOn the annular platform 9; the equal-thickness circular ring 3 at the edge of the plano-convex lens 1 is tightly contacted with the circular platform 9 (the prior art has a fixing function, the invention also has a sealing function, namely, a sealing gasket is arranged between the equal-thickness circular ring 3 and the circular platform 9, and the plano-convex lens 1 and the cylindrical container 2 are clamped by a clamp at the outer side); the diameter of the level 1 dark fringe and the 11 th, i.e., the diameter d1 and d11 of the dark fringe were measured, the central dark spot was assumed to be level 0, and S1= (d11/2) was calculated2-(d1/2)2(ii) a A groove 5 is formed in the left side of the inner side wall and the right side of the inner side wall of the cylindrical container 2, the groove 5 in the left side is communicated with a water inlet pipe 6, and liquid is injected into the water inlet pipe 6; the groove 5 on the right side of the cylindrical container 2 is connected with an air bag 7, a pipeline connected with the air bag 7 is provided with two air valves 8, the lower end air valve 8 is closed, the upper end air valve 8 is opened, the air bag 7 is extruded, so that the air inside the air bag 7 is discharged from the upper end air valve 8, and the upper end air valve 8 is closed, namely the upper end air valve 8 can communicate or close the air inside the air bag 7 and the air outside the air bag 7; the lower end air valve 8 is opened, the air bag 7 has elasticity, and the liquid of the water inlet pipe 6 can flow through a gap between the plano-convex lens 1 and the inner bottom surface of the cylindrical container 2 due to the elastic expansion of the air bag 7, even if the space between the plano-convex lens 1 and the inner bottom surface of the cylindrical container 2 is filled with the liquid; the diameter of the 1 st order dark fringe and the 11 th, i.e., the diameter d1 and d11 of the dark fringe were measured again, the central dark spot was set to 0 order, and Sn = (d11/2) was calculated2-(d1/2)2The refractive index of the liquid n = S1/Sn.

Claims (1)

1. The method for measuring the liquid refractive index by utilizing the Newton's ring comprises a plano-convex lens (1) and a cylindrical container (2), wherein the central part of the plano-convex lens (1) is a spherical surface (4), and the spherical surface center of the plano-convex lens (1) is contacted with the center of the bottom surface of the inner side of the cylindrical container (2), and is characterized in that: the edge of the plano-convex lens (1) is an equal-thickness circular ring (3); the edge of the inner side of the cylindrical container (2) is provided with a circular platform (9), and the circular ring (3) with the same thickness at the edge of the plano-convex lens (1) is placed on the circular platform (9); the equal-thickness circular ring (3) at the edge of the plano-convex lens (1) is tightly contacted with the circular platform (9) to play a role in sealing and fixing; the diameters d1 and d11 of the 1 st order dark streak and the 11 th order dark streak were measured, the central dark spotAssuming 0 th order, calculate S1= (d11/2)2-(d1/2)2(ii) a A groove (5) is formed in the left side of the inner side wall and the right side of the inner side wall of the cylindrical container (2), the groove (5) in the left side is communicated with a water inlet pipe (6), and liquid is injected into the water inlet pipe (6); a groove (5) on the right side of the cylindrical container (2) is connected with an air bag (7), a pipeline connected with the air bag (7) is provided with two air valves (8), the lower end air valve (8) is closed, the upper end air valve (8) is opened, the air bag (7) is extruded, so that the air on the inner side of the air bag (7) is discharged from the upper end air valve (8), the upper end air valve (8) is closed, namely the upper end air valve (8) can communicate or separate the air on the inner side of the air bag (7) and the air on the outer side of the; opening a lower end air valve (8), wherein the air bag (7) has elasticity, and the elastic expansion of the air bag (7) causes the liquid of the water inlet pipe (6) to flow through a gap between the planoconvex lens (1) and the inner bottom surface of the cylindrical container (2), even if the space between the planoconvex lens (1) and the inner bottom surface of the cylindrical container (2) is filled with the liquid; the diameter of the 1 st order dark grain and the diameters d1 and d11 of the 11 th order dark grain were measured again, the central dark spot was rated as 0, and Sn = (d11/2) was calculated2-(d1/2)2The refractive index of the liquid n = S1/Sn.
CN201911264013.9A 2019-12-11 2019-12-11 Method for measuring liquid refractive index by using Newton ring Pending CN110927112A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111579536A (en) * 2020-06-04 2020-08-25 重庆科技学院 Method for measuring total solid solubility of liquid by using improved Newton's ring
CN113250916A (en) * 2021-06-29 2021-08-13 中国华能集团清洁能源技术研究院有限公司 Fan tower barrel inclination monitoring device and method based on light interference

Citations (5)

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Publication number Priority date Publication date Assignee Title
CN2241142Y (en) * 1995-01-01 1996-11-27 陈仁麟 Liquid metering charging device
CN203607009U (en) * 2013-07-18 2014-05-21 内蒙古科技大学 Experiment equipment for Newton rings
CN105632306A (en) * 2016-04-07 2016-06-01 江南大学 Improved Newton's ring
CN206349046U (en) * 2016-11-21 2017-07-21 河南师范大学 A kind of Experiment of College Physics room Newton's ring instrument
CN207458423U (en) * 2018-03-20 2018-06-05 李育洁 A kind of Newton's ring of teaching

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2241142Y (en) * 1995-01-01 1996-11-27 陈仁麟 Liquid metering charging device
CN203607009U (en) * 2013-07-18 2014-05-21 内蒙古科技大学 Experiment equipment for Newton rings
CN105632306A (en) * 2016-04-07 2016-06-01 江南大学 Improved Newton's ring
CN206349046U (en) * 2016-11-21 2017-07-21 河南师范大学 A kind of Experiment of College Physics room Newton's ring instrument
CN207458423U (en) * 2018-03-20 2018-06-05 李育洁 A kind of Newton's ring of teaching

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Title
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111579536A (en) * 2020-06-04 2020-08-25 重庆科技学院 Method for measuring total solid solubility of liquid by using improved Newton's ring
CN113250916A (en) * 2021-06-29 2021-08-13 中国华能集团清洁能源技术研究院有限公司 Fan tower barrel inclination monitoring device and method based on light interference

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