Determination of liquid crystal refractive indices from critical angle measurements

1978 ◽  
Vol 25 (2) ◽  
pp. 206-210 ◽  
Author(s):  
D. Riviere ◽  
Y. Levy ◽  
C. Imbert
Keyword(s):  
Liquid Crystal ◽  
Critical Angle ◽  
Refractive Indices ◽  
Angle Measurements

Refractive index measurements and order parameter determination of the liquid crystal p-ethoxybenzilidene-p-n-butylaniline

1981 ◽  
Vol 59 (4) ◽  
pp. 515-520 ◽  
Author(s):  
P. Palffy-Muhoray ◽  
D. A. Balzarini
Keyword(s):  
Refractive Index ◽  
Liquid Crystal ◽  
Order Parameter ◽  
Orientational Order ◽  
Parameter Determination ◽  
Refractive Indices ◽  
Temperature Changes ◽  
Interferometric Technique ◽  
Anisotropic Fluids

Using a simple new interferometric technique, the ordinary and extraordinary refractive indices of the nematic liquid crystal p-ethoxybenzilidene-p-n-butylaniline have been measured separately as a function of temperature. Changes in the refractive indices have been measured with an accuracy of ±0.005% and the absolute values with an accuracy of ±0.5%. Thermal expansivity data has been obtained by utilizing a specially constructed thermometer containing the sample. By using a recently developed Clausius–Mossotti relation for anisotropic fluids, the effective molecular polarizability and hence the orientational order parameter have been obtained from refractive index and density measurements as a function of temperature.

The use of a slit in determining refractive indices with the microscope

1917 ◽  
Vol 18 (84) ◽  
pp. 130-132
Author(s):  
John William Evans
Keyword(s):  
Crystal Structure ◽  
Refractive Index ◽  
Optical Properties ◽  
Critical Angle ◽  
Total Reflection ◽  
Index Of Refraction ◽  
Refractive Indices ◽  
Object Image ◽  
Ordinary Object

Certain optical properties of crystals, and more particularly the refractive index, may be determined either in the directions-image, often referred to as the 'image in convergent light', or in the ordinary object-image in which the object itself is seen. In the former case, in which the index of refraction is 'usually determined by means of the critical angle of total-reflection, every point in the image corresponds to a single direction of propagation of the wave-front through the crystal-structure and to the two corresponding directions of vibration. One of these can, however, be eliminated by the insertion of a nicol in an approximate position, and thus all ambiguity in the determination of the refractive index is removed.

Conoscopic method for determination of main refractive indices and thickness of a uniaxial crystal cut out parallel to its optical axis

2009 ◽  
Vol 42 (5) ◽  
pp. 878-884 ◽  
Author(s):  
Leonas Dumitrascu ◽  
Irina Dumitrascu ◽  
Dana Ortansa Dorohoi
Keyword(s):  
Liquid Crystal ◽  
Optical Axis ◽  
Ccd Camera ◽  
Uniaxial Crystal ◽  
Refractive Indices ◽  
Anisotropic Layer ◽  
Analysis Technique ◽  
Planar Orientation ◽  
Optical Sign

This paper presents a simplified data acquisition and analysis technique for use in determining the main refractive indices and thickness of a uniaxial anisotropic layer cut out parallel to the optical axis, by processing the conoscopic interference figures obtained using a polarizing microscope equipped with a CCD camera. For negative uniaxial crystals, the equations used permit the calculation of the optical sign of the studied material so it is not necessary to insert a quartz wedge into the conoscopic beam. The technique can also be applied to the study of liquid crystal layers in a planar orientation.

Photogrammetric determination of the refractive properties of liquid crystal displays

2019 ◽  
Vol 86 (6) ◽  
pp. 319-324
Author(s):  
Marcus Petz ◽  
Hanno Dierke ◽  
Rainer Tutsch
Keyword(s):  
Liquid Crystal ◽  
Measurement Uncertainty ◽  
Liquid Crystal Displays ◽  
Refractive Indices ◽  
Simultaneous Observation ◽  
Glass Substrates ◽  
Contrast Pattern ◽  
Optically Detected ◽  
First Time

AbstractIn phase-measuring deflectometry for measuring reflecting and transparent surfaces, a high-contrast pattern displayed on a liquid crystal screen is usually optically detected. One of the most important non-idealities of liquid crystal displays with regard to the achievable measurement uncertainty is the refraction in the glass substrate, which leads to an angle-dependent offset between the actual location and the observed location of a feature displayed on the screen. Owing to the typical thicknesses and refractive indices of the glass substrates used, this offset reaches several tenths of a millimeter even at moderate viewing angles. In the approach presented here, the refraction-related offset of features displayed on the screen is determined by simultaneous observation of displayed features and features mounted on the screen. The model used so far was improved, so that apart from a distance of the features to be determined before the evaluation no further previous knowledge is necessary. Within the scope of the investigations carried out, statements on the measurement uncertainty of the method could also be made and verified for the first time.

scholarly journals Experimental Determination of Stator Endwall Heat Transfer

1989 ◽  
Author(s):  
Robert J. Boyle ◽  
Louis M. Russell
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Test Section ◽  
Electrical Power ◽  
Exhaust System ◽  
Ambient Air ◽  
Reynolds Numbers ◽  
Inlet Velocity ◽  
Turbine Vane

Local Stanton numbers were experimentally determined for the endwall surface of a turbine vane passage. A six vane linear cascade having vanes with an axial chord of 13.81 cm was used. Results were obtained for Reynolds numbers based on inlet velocity and axial chord between 73,000 and 495,000. The test section was connected to a low pressure exhaust system. Ambient air was drawn into the test section, inlet velocity was controlled up to a maximum of 59.4 m/sec. The effect of the inlet boundary layer thickness on the endwall heat transfer was determined for a range of test section flow rates. The liquid crystal measurement technique was used to measure heat transfer. Endwall heat transfer was determined by applying electrical power to a foil heater attached to the cascade endwall. The temperature at which the liquid crystal exhibited a specific color was known from a calibration test. Lines showing this specific color were isotherms, and because of uniform heat generation they were also lines of nearly constant heat transfer. Endwall static pressures were measured, along with surveys of total pressure and flow angles at the inlet and exit of the cascade.

Determination of Temperature Dependence of Kerr Constant for Nematic Liquid Crystal

2011 ◽  
Vol 544 (1) ◽  
pp. 227/[1215]-231/[1219] ◽  
Author(s):  
M. H. Majles Ara ◽  
S. H. Mousavi ◽  
M. Rafiee ◽  
M. S. Zakerhamidi
Keyword(s):  
Liquid Crystal ◽  
Temperature Dependence ◽  
Nematic Liquid Crystal ◽  
Kerr Constant
Sign in / Sign up

Export Citation Format

Share Document