Torque optical

Our objective is to design an optical device that will change the polarization from horizontal to vertical linear polarization - a rotation of the Stokes vector 5i,52,53 from // = (1,0,0 to V = (0,1,0 - and to do so independently of the wavelength. For this purpose, we require a propagation equation for the Stokes vector, obtained from Eq. (5.14) and the definitions (5.16) in much the same way that Feynman et al. [9] convert the two-state TDSE into a torque equation for combinations of products of probability amplitudes see Appendix 5.B. The equations... 

There are a large number of designs for all types of torsional apparatus, mostly home made. In apparatus for torsional creep the measurement of displacement may be made by a variety of methods e.g. optical lever and spot-following recorder, or electrical sensing. The application of the torque may be made by means of weights or electrically. 

Ferraro and coll, used canonical transformation of the Hamiltonian to resolve the average optical rotatory power of a molecule into atomic contributions, based on the acceleration gauge for the electric dipole, and/or the torque formalism [151], This method has been applied to the study of the conformational profile of the optical rotatory poser of hydrogen peroxide and hydrazine [152]. 

Power measurements require the measurement of the torque and the rotational speed. The torque can be measured using a torsion shaft with strain gauges, electrically with eddy-current torque transducers, or mechanically with a swiveling motor. The speed of rotation can be measured using mechanical, electrical (photocell), or optical (stroboscope) instruments. 

Nanorotors using asymmetric inorganic nanoroda in an optical trap driving torque r will scale as... 

The application of an electric field above the threshold value results in a reorientation of the nematic liquid crystal mixture, if the nematic phase is of negative dielectric anisotropy. The optically active dopant then applies a torque to the nematic phase and causes a helical structure to be formed in the plane of the display. The guest dye molecules are also reoriented and, therefore, the display appears coloured in the activated pixels. Thus, a positive contrast display is produced of coloured information against a white background. The threshold voltage is dependent upon the elastic constants, the magnitude of the dielectric anisotropy, and the ratio of the cell gap to the chiral nematic pitch ... 

Anisotropic molecules show optically isotropic behavior in the bulk when they are disordered and randomly oriented, for instance in solutions or liquid crystal above the transition temperature. Under the influence of a strong beam, the induced dipole moment of the molecules feels a torque that tends to orient the molecule. The reorientation of the molecular dipoles induces a change in the refractive index. The typical values for molecular susceptibilities and the time-responses vary depending on the type of systems. For small anisotropic molecular systems, x 10 esu, with a time response 10 s. However, in the nematic phase, liquid crystal molecules are strongly correlated, resulting in much higher values, x 10 esu,... 

D.S. Bradshaw, D.L. Andrews, Optically Induced Forces and Torques Interactions Between Nanoparficles in a Laser Beam. Phys. Rev. A 76 (2005) 033816. 

The distinction between a force sensor and a torque sensor is not clear, because in all cases a mechanical movement resulting from a force is converted into optical, electrical, or magnetic signals. This conversion defines the characteristics of the sensor. All sensors are made for limited ranges. 

One of the latest developments in the area of steering torque sensors is an optical concept created by Bishop Innovation with Bosch. As in conventional hydraulic steering systems, a torsion bar is a part of the steering column. A disc with a barcode on its surface is attached to each end of the torsion bar. A light source within the sensor module illuminates the surface of the coded discs, partially reflecting the light through a lens onto an optoelectronic ASIC. 

The light intensity on the sensitive surface of the optical ASIC, an array of photodiodes, depends on the code of the discs. The intensity distribution over the photodiodes allows the optoelectronic ASIC to calculate the absolute angular position and the angular displacement of the steering shaft Fig. 7.12.6 shows the sensor concept. This concept allows measurement of the absolute angular position of the steering wheel and the torque applied to the steering system. 

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