Influence of Refractive Index Gradients within droplets on rainbow position and implications for rainbow refractometry

1996 ◽  
Vol 13 (2) ◽  
pp. 125-129 ◽  
Author(s):  
Klaus Anders ◽  
Norbert Roth ◽  
Arnold Frohn
Keyword(s):  
Refractive Index ◽  
Rainbow Refractometry

A Study on the Evaporation of Water–Ethanol Mixture Using Rainbow Refractometry

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Jantarat Promvongsa ◽  
Bundit Fungtammasan ◽  
Grehan Gerard ◽  
Sawitree Saengkaew ◽  
Pumyos Vallikul
Keyword(s):  
Refractive Index ◽  
Volume Fraction ◽  
Liquid Droplet ◽  
Droplet Diameter ◽  
Pure Water ◽  
Volatile Component ◽  
Ethanol Mixture ◽  
Steady Stage ◽  
Composition Gradients ◽  
Rainbow Refractometry

Evaporation of droplets of liquid mixture is a subject of interest in combustion studies, e.g., combustion of bioethanol blends. In this paper, experimental investigation, using rainbow refractometry, on the variations of droplet diameter and composition during the evaporation of water–ethanol droplet in quiescent atmosphere is studied. The droplet is suspended on the tip of 125 μm-diameter fiberglass rod. The initial diameter is around 1000–1100 μm, and the initial composition is varied from 0% to 100% of ethanol by volume. The scattered rainbow signal from the evaporating droplet is fitted to the Airy theory to extract information on the diameter and refractive index of the liquid droplet against evolution time. To determine the accuracy of droplet diameter measurements using this technique, the diameter is also measured from the shadow image of droplet simultaneously. At 0–60% of ethanol by volume, the diameter and volume fraction accuracies are within ±30 μm and 10%, respectively, even though the temperature and composition gradients inside a droplet are neglected. The results show that the water–ethanol mixture evaporates faster at the beginning due to the higher amount of the volatile component, i.e., ethanol. The D2–t curve appears as a series of two straight lines of different slopes: a steep one initially and a moderate one at later stage. The slope at the initial or the transition stage increases with the ethanol composition, while the slope at later stage (steady stage) is equivalent to that of pure water. Likewise, the refractive index decreases rapidly at the beginning and becomes steady reaching a final value of 1.333, which is close to the refractive index of pure water.

scholarly journals Optical characterization of ethane droplets in the vicinity of critical pressure

2020 ◽  
Vol 75 ◽  
pp. 59 ◽  
Author(s):  
Chanisa Kanjanasakul ◽  
Frédéric Grisch ◽  
Sawitree Saengkaew ◽  
Gérard Gréhan
Keyword(s):  
High Pressure ◽  
Refractive Index ◽  
Critical Point ◽  
Critical Pressure ◽  
Fuel Injection ◽  
Index Of Refraction ◽  
Fuel Droplets ◽  
Thermodynamic Conditions ◽  
Rainbow Refractometry

The characterization of the properties of fuel droplets around the critical pressure is an experimental challenge. The aim of this study is to measure the size and the refractive index of droplets in high pressure conditions, close to the ones of the critical point. For this purpose, an experimental facility of injection of quasi-monodispersed droplets at high pressure has been developed. Rainbow refractometry has been used to probe droplets in the pressure range 1–50 bar. For water and ethanol droplets, evolutions of their index of refraction with pressure were obtained. For measurements with a liquid fluid near its critical point, ethane was selected because its critical point is 48.7 bar and 32.2 °C. Refractive index measurements on ethane droplets were carried out in the range of pressure and temperature 40–46 bar and 18–25 °C respectively. These unique results show that the rainbow refractometry diagnosis offers undeniable potentials for studying fuel injection under transcritical thermodynamic conditions.

Secondary rainbow refractometry for droplet refractive index and size measurement

2022 ◽  
Vol 149 ◽  
pp. 106831
Author(s):  
Xinhao Wang ◽  
Yingchun Wu ◽  
Qimeng Lv ◽  
Xuecheng Wu
Keyword(s):  
Refractive Index ◽  
Size Measurement ◽  
Rainbow Refractometry

TEM characterization of proton-exchanged LiNbO3 optical waveguides

1986 ◽  
Vol 44 ◽  
pp. 480-481
Author(s):  
W. E. Lee
Keyword(s):  
Refractive Index ◽  
Benzoic Acid ◽  
Optical Waveguides ◽  
Total Internal Reflection ◽  
Index Of Refraction ◽  
Optical Measurements ◽  
Lithium Ions ◽  
Wide Channel ◽  
Tem Characterization

An optical waveguide consists of a several-micron wide channel with a slightly different index of refraction than the host substrate; light can be trapped in the channel by total internal reflection.Optical waveguides can be formed from single-crystal LiNbO3 using the proton exhange technique. In this technique, polished specimens are masked with polycrystal1ine chromium in such a way as to leave 3-13 μm wide channels. These are held in benzoic acid at 249°C for 5 minutes allowing protons to exchange for lithium ions within the channels causing an increase in the refractive index of the channel and creating the waveguide. Unfortunately, optical measurements often reveal a loss in waveguiding ability up to several weeks after exchange.

Light microscopy of ceramics

1993 ◽  
Vol 51 ◽  
pp. 908-909
Author(s):  
Walter C. McCrone
Keyword(s):  
Refractive Index ◽  
Light Microscopy ◽  
Light Microscope ◽  
Polarized Light ◽  
Refractive Indices ◽  
Complete Coverage ◽  
The Subject ◽  
Lower Refractive Index

An excellent chapter on this subject by V.D. Fréchette appeared in a book edited by L.L. Hench and R.W. Gould in 1971 (1). That chapter with the references cited there provides a very complete coverage of the subject. I will add a more complete coverage of an important polarized light microscope (PLM) technique developed more recently (2). Dispersion staining is based on refractive index and its variation with wavelength (dispersion of index). A particle of, say almandite, a garnet, has refractive indices of nF = 1.789 nm, nD = 1.780 nm and nC = 1.775 nm. A Cargille refractive index liquid having nD = 1.780 nm will have nF = 1.810 and nC = 1.768 nm. Almandite grains will disappear in that liquid when observed with a beam of 589 nm light (D-line), but it will have a lower refractive index than that liquid with 486 nm light (F-line), and a higher index than that liquid with 656 nm light (C-line).

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