Conical extinction curves: a new universal stage technique

1964 ◽  
Vol 33 (265) ◽  
pp. 853-867 ◽  
Author(s):  
N. Joel ◽  
F. E. Tocher
Keyword(s):  
Uniaxial Crystal ◽  
Optic Axis ◽  
Circular Cone ◽  
Biaxial Crystal ◽  
Universal Stage

SummaryNew generalized extinction curves, derived from wave-normals located on a circular cone, are presented. They may be used with the universal stage for the accurate location of up to all three of the indicatrix axes, α, β, γ, of any biaxial crystal, or the optic axis of any uniaxial crystal.

New techniques for the universal stage. II. The determination of the 2V when only one optic axis is accessible

1958 ◽  
Vol 31 (241) ◽  
pp. 878-882 ◽  
Author(s):  
N. Joel ◽  
I. D. Muir
Keyword(s):  
Normal Incidence ◽  
Optic Axis ◽  
Sufficient Accuracy ◽  
Stage Ii ◽  
Biaxial Crystal ◽  
New Techniques ◽  
Axial Angle ◽  
Universal Stage

SummaryWhen one optic axis of a biaxial crystal has been located accurately by the usual orthoseopic or conoscopic methods, the second may be located by determining the extinction positions at normal incidence and applying the Biot-Fresnel construction. When use is made of the extinction directions associated with two or more wave normals inclined to the section, this method gives more reliable values of the optic axial angle than can be obtained by the doubling of the angle V over the pole of a bisectrix. If the optic axes have been located with sufficient accuracy by this procedure, then this also determines the orientation of the indicatrix.

scholarly journals Birefrince Characteristics of an Optical Element

2019 ◽  
Vol 8 (9S3) ◽  
pp. 801-803
Keyword(s):  
Phase Difference ◽  
Optical Element ◽  
Uniaxial Crystal ◽  
Optic Axis ◽  
Intensity Measurement ◽  
Double Refraction ◽  
Varying Thickness

Phase difference variation in uniaxial crystal is investigated for varying thickness. Using double refraction property and optic axis method leads to the intensity measurement. The periphery example got when a unique (or focalized) shaft experiences an example of birefringent gem between two polarizers contains data which is intrinsic of the crystalline example under examination.

The measurement of large optic axial angles with the universal stage

1966 ◽  
Vol 35 (273) ◽  
pp. 763-769
Author(s):  
M. Munro
Keyword(s):  
Refractive Index ◽  
Rapid Method ◽  
High Refractive Index ◽  
Optic Axis ◽  
Relative Speed ◽  
Accuracy And Precision ◽  
Direct Location ◽  
Speed Accuracy ◽  
Universal Stage ◽  
Low Refractive Index

SummaryA comparison has been made of the relative speed, accuracy, and precision of several methods of measuring large optic axial angles with the universal stage. It is concluded that a method based on the direct location of a single optic axis and the application of the Biot-Fresnel law will frequently be the most satisfactory when only the standard, low refractive index centre plate for the stage is available. If a centre plate of high refractive index is employed, however, good results can normally be obtained by using the more rapid method based on the direct location of both optic axes.

Directional Dispersion and Assignment of Optical Phonons in LiNbO3

1972 ◽  
Vol 27 (8-9) ◽  
pp. 1187-1192 ◽  
Author(s):  
R. Claus ◽  
J. Brandmüller ◽  
G. Borstel ◽  
E. Wiesendanger ◽  
L. Steffan
Keyword(s):  
Short Wavelength ◽  
Uniaxial Crystal ◽  
Optic Axis ◽  
Optical Phonons ◽  
Dispersion Theory ◽  
Phonon Modes ◽  
Phonon Wave Vector ◽  
Complete Assignment ◽  
Firm Basis ◽  
Degenerate Type

Abstract From the general polariton dispersion theory it can be shown that in an uniaxial crystal the frequencies of optical phonons * which are identical to those of the short wavelength polaritons depend on the angle Θ between the optic axis and the phonon wave vector. For Θ=0 and Θ=Π/2 the phonons are exactly transversal or longitudinal so that they can be assigned to be of totally symmetric or twofold degenerate type. Careful measurements of the directional dispersion of all phonon modes of LiNbO3 form a firm basis for a new complete assignment. 6 of the total number of 13 dispersion branches previously given in the literature had to be reassigned.

A new universal stage extinction technique: the determination of 2 V when neither optic axis is directly observable

1964 ◽  
Vol 33 (266) ◽  
pp. 1038-1054 ◽  
Author(s):  
F. E. Tocher
Keyword(s):  
Optic Axis ◽  
Wave Normal ◽  
Special Case ◽  
Universal Stage

SummaryA new universal stage extinction technique is presented. It is based on the special case of coplanar and conical extinction curves where an optic axis lies on the wave-normal locus. It may be used in favourable circumstances to determine 2V when neither optic axis is directly observable.

The detection of rotatory polarization in an orthorhombic crystal exhibiting crossed axial dispersion

1923 ◽  
Vol 20 (102) ◽  
pp. 123-130 ◽  
Author(s):  
Gilbert Greenwood
Keyword(s):  
Quartz Crystal ◽  
Optic Axis ◽  
Axial Dispersion ◽  
Biaxial Crystal ◽  
Orthorhombic Crystal ◽  
Double Refraction

The existence of rotatory polarization is comparatively easy to detect in isotropic crystals and in uniaxial crystals in the direction of the optic axis ; but in a biaxial crystal the problem presents far greater difficulties, since in general the rotatory polarization is obscured by the double refraction. The possibility of its existence in a biaxial crystal was denied by É. Mallard (Traité de Cristallographie, 1884, vol. 2, p. 818). However, the persistence of rotatory polarization in a quartz crystal , made biaxial by pressure, brought this conclusion into doubt. Later work, both experimental and theoretical, by H. C. Pocklington (Phil. Mag., 1901, ser. 6, vol. 2, p. 861) established its presence in certain biaxial crystals.

Optical determination of aegirine-augite with the universal stage

1962 ◽  
Vol 33 (257) ◽  
pp. 132-137 ◽  
Author(s):  
Basil C. King
Keyword(s):  
Accurate Determination ◽  
Optic Axis ◽  
Strong Absorption ◽  
Alternative Procedure ◽  
Optical Determination ◽  
The One ◽  
Absorption And Dispersion ◽  
Universal Stage

SummaryThe accurate determination of α:[001] and 2V in members of the aegirine-augite series often presents difficulties owing to strong absorption and dispersion, especially as high angles of tilt on the universal stage are often involved. Both of these angles depend on the location of α, and this operation is the one most subject to error.An alternative procedure is the determination of A:[001], the angle between an optic axis and [001]. This angle is very easily and accurately determined and varies systematically with composition. It can be derived from the values for α:[001] and 2V, while conversely values of α:[001] and 2V can be obtained from A:[001] by reference to standard curves.

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