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Optical activity is reciprocal, i.e. it is the same for opposite directions of wave propagation through an optically active medium, for example, clockwise polarization rotation from the point of view of an observer.
Recording optical rotation with a polarimeter: The plane of polarisation of plane polarised light (4) rotates (6) as it passes through an optically active sample (5). This angle is determined with a rotatable polarizing filter (7). In chemistry, specific rotation ([α]) is a property of a chiral chemical compound.
In all materials the rotation varies with wavelength. The variation is caused by two quite different phenomena. The first accounts in most cases for the majority of the variation in rotation and should not strictly be termed rotatory dispersion. It depends on the fact that optical activity is actually circular birefringence.
Determination of specific rotation: In order to determine a specific rotation of an optically active substance (say, sugar), the polarimeter tube is first filled with pure water and the analyzer is adjusted for equal darkness (both the halves should be equally dark) point. The position of the analyzer is noted with the help of the scale.
A half-wave plate rotates polarization by 90° A polarization rotator is an optical device that rotates the polarization axis of a linearly polarized light beam by an angle of choice. Such devices can be based on the Faraday effect, on birefringence, or on total internal reflection. [1]
Four weeks before he presented his completed theory of total internal reflection and the rhomb, Fresnel submitted a memoir [30] in which he introduced the needed terms linear polarization, circular polarization, and elliptical polarization, [31] and in which he explained optical rotation as a species of birefringence: linearly-polarized light ...
Rotational transitions, in which the molecule gains a quantum of rotational energy. Atmospheric water vapour at ambient temperature and pressure gives rise to absorption in the far-infrared region of the spectrum, from about 200 cm −1 (50 μm) to longer wavelengths towards the microwave region.
Then by implementing a Faraday rotator with a rotation of 45°, inadvertent downstream reflections from a linearly polarized source will return with the polarization rotated by 90° and can be simply blocked by a polarizer; this is the basis of optical isolators used to prevent undesired reflections from disrupting an upstream optical system ...