Birefringent prisms

Diperoxotriamminechromium(IV) crystallizes in rhombic birefringent prisms of density 1.96 g./ml. (15°), which appear as deep brownish-red to black needles. Although insoluble in most solvents, it may be recrj stallized from aqueous ammonia. It is soluble in water with decomposition. The absorption spectra, magnetic susceptibility, and crystal structure of the compound have been measured. A crystallographic study reports the structure as a deformed pentagonal bipyramid. A recent investigation of the infrared spectrum" shows the presence of peroxide bands. 

Let us assume that the refractive indices of the birefringent prism (it can be a crystal or liquid crystal) are ng=. l and = 1.5. Then, in order to get 1° steering angle, the required prism angle should be 5°. By stacking N basic units whose a values are in binary sequence, then... 

Figure C3.1.13. Experimentai configuration for far-UV nanosecond CD measurements using a frequency-upconverted Ti sapphire iaser as a probe source. Pj and P2 are Mgp2 Rochon poiarizers at cross orientations. SP is a strained transparent piate with about i ° of iinear birefringence for quasi-nuii eiiipsometric CD detection. Prism PMj and the iris Ij seiect the far-UV fourth hannonic of the argon iaser-pumped Ti-sapphire iaser s near-IR fundamentai output to probe the eiiipticity of the sampie. A second iaser beam at 532 nm is used to pump CD...

In thin sections natural graphite is translucent, strongly pleochroic, and uniaxial. It has a negative sign of birefringence and two extinctions per revolution under crossed Nicol prisms. The atomic number of carbon accounts for its low absorption coefficient for x-rays and electrons. 

The just described compensation method for the parasitic birefringence of windows and polarizing prisms is also useful with respect to the parasitic birefringence created by reflections from the cylinder walls. As has been pointed out, the disturbance caused by the windows is compensated at its maximum. This means, as the test fluid possesses an extinction angle of 45°, that the extinction positions of the window birefringence are oriented parallel and perpendicular to the direction of flow (i.e. the... 

The experimental value reported for PDN6S in Table V is very preliminary and is based on only three experimental points derived from prism-coupled waveguide reflectivity measurements. At this point, spurious effects due to heating, photoinduced birefringence etc. can not be conclusively ruled out. This preliminary data is presented only to provide a comparison with the calculated value. 

Refractive index (RI) of a solid can easily be measured using a reffactome-ter, as long as an object can be placed in contact with the prism on the instrument. Liquid refractometers exist for the determination of RI of solutions. Both the RI and the birefringence (range between refractive indices) are diagnostic and constant for a pure substance. 

Nicol prisms coincide with those of the crystal (ordinary and extraordinary rays) [see Fignre 5.13(c)]. In other positions the color is determined by the birefringence of the crystal, the direction of the light and the thickness of the crystal. This method can be used to determine whether the crystal is single or not, since two or more misaligned crystals (twins) do not extinguish the light completely. 

Microcrystalline powder strongly birefringent oblong prisms with beveled end faces. Soluble in HgO. Contains (as impurity) 0.2-0.3 moles of NaOH per mole of aluminate. 

There are numerous polarizing optical components available. Their operation is based on birefringence, polarization at mirrors at the Brewster angle, optical dichroism, etc. Precision achieved with sheet polarizers is inadequate, thus devices like Glan-Thompson, Glan-Foucault or Rochon prisms have to be used. 

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