scholarly journals The refractive index and dispersion of light in argon and helium

1908 ◽  
Vol 80 (540) ◽  
pp. 390-405 ◽  
Keyword(s):  
Refractive Index ◽  
Wave Length ◽  
Mercury Vapour ◽  
Horizontal Beam ◽  
Absolute Refractive Index ◽  
The Absolute ◽  
Cross Wire ◽  
Plane Diffraction ◽  
Interferometer Method ◽  
Dispersion Of Light

The initial object of this research was to find the dispersion of light in the monatomic gases argon and helium, but as it was necessary to know the absolute value of the refractive index with considerable accuracy, determinations of the refractive index have also been made. Their relative refractive powers (air = 1 ) have been found by Rayleigh, and Ramsay and Travers, using coloured interference fringes, but no determinations of the absolute refractive index for light of given wave-length have hitherto been made. The interferometer method due to Jamin was used. A horizontal beam of parallel white light was incident on the first Jamin plate. The two reflected beams traversed two brass tubes of equal length closed by equal thicknesses of worked plane glass. Each brass tube had a small side tube attached which led to apparatus for altering the density in the tube and measuring its pressure. After reflection at the second Jamin plate, the recombined beam was focussed on the slit of a spectrometer, the spectrum obtained with a plane diffraction grating was examined through the telescope of the spectrometer and was seen crossed by bands of maximum and minimum intensity. At the same time, by means of a small reflecting prism, a portion of the slit was illuminated by the light from a Plücker tube containing hydrogen, helium, and mercury vapour. Thus one observed simultaneously the interference bands and certain standard lines of known wave-length with any one of which the cross wire of the telescope could be brought into coincidence.

High-accuracy interferometer with a prism pair for measurement of the absolute refractive index of glass

2009 ◽  
Vol 48 (11) ◽  
pp. 2045 ◽  
Author(s):  
Yasuaki Hori ◽  
Akiko Hirai ◽  
Kaoru Minoshima ◽  
Hirokazu Matsumoto
Keyword(s):  
Refractive Index ◽  
High Accuracy ◽  
Absolute Refractive Index ◽  
The Absolute ◽  
Prism Pair

scholarly journals Magnetic double-refraction in liquids. part I.—benzene and its derivatives

1927 ◽  
Vol 113 (765) ◽  
pp. 511-519 ◽  
Keyword(s):  
Magnetic Field ◽  
Refractive Index ◽  
Incident Light ◽  
Wave Length ◽  
Absolute Temperature ◽  
Organic Liquids ◽  
Detectable Effect ◽  
Double Refraction ◽  
Absolute Value ◽  
The Absolute

Many organic liquids exhibit a feeble double-refraction when they are placed in a strong magnetic field and a beam of light traverses the substances in a direction transverse to the lines of force. The magnitude of this effect, which was discovered in 1907 by Cotton and Mouton, depends very largely on the chemical structure of the molecule. Hydrocarbons belonging to the aliphatic series and the aromatic series are strikingly different in their behaviour; hexane, for instance, showing no detectable effect, while benzene is an example of a liquid showing a measurable double-refraction. We propose in the series of papers of which this is the first, to discuss this phenomenon in its relation to the structure of molecules and their magnetic properties. For this purpose we shall use the theory of Langevin, which explains magnetic double-refraction as an effect arising from the orientative action of the field on the molecules (assumed to be magnetically and optically anisotropic) and connects the absolute value of the Cotton-Mouton constant with the values of the optical refractivity and of the magnetic susceptibility of the molecule along three mutually perpendicular axes. To enable the formula of Langevin to be used for the purpose of calculating the absolute value of the Cotton-Mouton constant, it is necessary to have data concerning, firstly, the magnetic character of the molecule, and, secondly, its optical anisotropy. In regard to the latter, we propose to utilise the data obtained from observations on light-scattering in the liquids concerned. In regard to the magnetic anisotropy of the molecules, we shall endeavour to connect the indications furnished by the data on magnetic double-refraction with considerations of atomic and mole-cular structure and the well-known theory of diamagnetism, also due to Langevin. We shall here merely quote the formula due to Langevin, the derivation of which is very conveniently set out in a recent article by Debye. The Cotton-Mouton constant Cm of double-refraction is given by the relation C m ═n p ─n q /λH 2 ═3(n 0 ─1 2 /80Пn 0 λKT v .[(A─B)(A'B')+(B─C) (B'─C')+(C─A)(C'─A')/(A+B+C) 2 ,1 Where A, B, C are the moments induced along the three mutually perpendicular axes of the optical ellipsoid of the molecule by unit electric force in the incident light-waves, acting respectively along the three axes, and A', B', C' are the magnetic moments induced in the molecule by unit magnetic force acting in the same three directions. H is the acting magnetic field, λ is the wave-length of the light, k is the Boltzmann constant, T the absolute temperature, v the number of molecules per unit volume, n 0 the refractive index of the liquid outside the field, and n p and n q are the principal refractive indices in the field. The quantities A, B, C are connected with the refractive index n 0 of the liquid by the relation.

scholarly journals On the theory of certain bands seen in the spectrum

1851 ◽  
Vol 5 ◽  
pp. 794-796
Keyword(s):  
Refractive Index ◽  
Refractive Indices ◽  
Great Precision ◽  
Practical Applications ◽  
Absolute Refractive Index ◽  
The Absolute ◽  
The Wire ◽  
Fixed Line ◽  
Different Parts

The principal object of the author in this communication is to point out some practical applications of the interference bands recently discovered by Professor Powell, the theory of which was considered by the author in the paper to which the present is a supplement. The bands seem specially adapted to the determination of the dispersion in media which cannot be procured in sufficient purity to exhibit the fixed lines of the spectrum. The ordinary experiments of interference allow of the determination of refractive indices with great precision; but in attempting to determine in this way the dispersion of the retarding plate employed, there is the want of a definite object to observe in connection with the different parts of the spectrum. In Professor Powell’s experiment, the wire of the telescope, placed in coincidence with one of the fixed lines of the spectrum previously to the insertion of the retarding plate into the fluid, marks the place of the fixed line, and so affords a definite object to observe when the retarding plate is inserted into the fluid, and the spectrum is consequently traversed by bands of interference. The practical applications considered by the author are principally four. In the first, the variation of the refractive index of the plate in passing from one fixed line to another is determined, the absolute refractive index for some one fixed line being supposed accurately known. The observation consists in counting the number of bands seen between two fixed lines of the spectrum, the fractions of a band-interval at the two extremities being measured or estimated.

scholarly journals Absolute temperature directly from plank’s profile: A simulation

2021 ◽  
Vol 33 (2) ◽  
pp. 9-19
Author(s):  
V. VIJAYAKUMAR ◽  
Keyword(s):  
Thermal Radiation ◽  
Response Function ◽  
Wave Length ◽  
Absolute Temperature ◽  
Scale Factor ◽  
Material Surface ◽  
Measured Spectrum ◽  
The Absolute

The measured thermal radiation from a material surface will, in general, have a wave length (\lambda) dependent scale-factor to the Planck profile (PT) from the contributions of the emissivity (Є\lambda) of the surface, the response function (A\lambda) of the measurement setup, and the emission via non-Plank processes. For obtaining the absolute temperature from such a profile, a procedure that take care of these dependencies and which relay on a temperature grid searchis proposed. In the procedure, the deviation between the Plank profiles at various temperatures and the measured spectrum that is made equal to it at a selected wavelength, by scaling, is used. The response function (A\lambda) is eliminated at the measurement stage and the polynomial dependence of the remnant scale factor mostly dominated by Є\lambda) i s extracted from the measured spectrum by identifying its optimal \lambda dependence. It is shown that when such a computation is carried out over a temperature grid, the absolute temperature can be identified from the minimum of the above deviation. Here, search for T and Є\lambda) d elinked, unlike in the leastsquare approaches that are normally employed. Code that implements the procedure is tested with simulated Planck profile to which different viable values of Є\lambda) a nd noise is incorporated. It shown that if the \lambda dependence of scale-factor is not too high, the absolute temperature can be recovered. A large \lambda dependent scale-factor and the consequent possible error in the temperature obtained can also be identified.

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