Prism, optical

In many spectrometric instruments, the monochromator is based on prism optics (figure 7.6). This is particularly true of cheaper instruments. When a beam of polychromatic radiation passes through a prism, the light is refracted from its original path. The higher the frequency of the radiation, the greater... 

Crystal Properties3 Lone orthorhombic prisms optically (+)... 

When the sample is introduced between the polarizer and analyzer prism, optical rotation is produced, i.e., the plane polarized light emitted by the polarizer is rotated. The extent of rotation can be measured by rotating the analyzer with respect to the polarizer till the rotation is fully compensated. In more sophisticated instruments, a quartz-wave compensator is introduced. In these instruments, the polarizer and the analyzer are left permanently crossed... 

A few polymer chains chemically end labeled with a fluorescent probe (NBD) are mixed to the polymer melt (4). The sample is a drop of this mixture (optical index, 03), squeezed between a moving plate and the upper surface of a silica prism (optical index, ni > n2) which form the walls of a plane Couette cell. Two laser beams (wavelength in vacuum Xq) impinge on the prism surface at an incidence angle 0i greater than the critical angle for total internal reflection, 0c = sin (n2/ni). They both... 

The physics of X-ray refraction are analogous to the well known refraction of light by optical lenses and prisms, governed by Snell s law. The special feature is the deflection at very small angles of few minutes of arc, as the refractive index of X-rays in matter is nearly one. Due to the density differences at inner surfaces most of the incident X-rays are deflected [1]. As the scattered intensity of refraction is proportional to the specific surface of a sample, a reference standard gives a quantitative measure for analytical determinations. 

The two essential elements of an electron spectrometer are the electrodes that accelerate electrons and focus them into a beam and the dispersive elements that sort electrons according to their energies. These serve the fimctions of lenses and prisms in an optical spectrometer. The same parameters are used to describe these elements in an electron spectrometer as in an optical spectrometer the teclmology is referred to as electron optics. 

Figure B2.1.1 Femtosecond light source based on an amplified titanium-sapphire laser and an optical parametric amplifier. Symbols used P, Brewster dispersing prism X, titanium-sapphire crystal OC, output coupler B, acousto-optic pulse selector (Bragg cell) FR, Faraday rotator and polarizer assembly DG, diffraction grating BBO, p-barium borate nonlinear crystal.

The shortest optical pulses actually used so far (1998) in ultrafast spectroscopic experunents were obtained by Shank and co-workers from an amplified CPM laser [ ]. In these extraordinary experiments, a sequence of a pair of prisms... 

The racemic acid is not a primary product of plant processes but is formed readily from the dextrorotatory acid by heating alone or with strong alkaU or strong acid. The methods by which such racemic compounds can be separated into the optically active modifications were devised by Pasteur and were apphed first to the racemic acid. Racemic acid crystallizes as the dihydrate triclinic prisms. It becomes anhydrous on drying at 110°C... 

Optical Applications. Vitreous siUca is ideal for many optical appHcations because of its excellent ultraviolet transmission, resistance to radiation darkening, optical polishing properties, and physical and chemical stabiUty. It is used for prisms, lenses, cells, wiadows, and other optical components where ultraviolet transmission is critical. Cuvettes used ia scatter and spectrophotometer cells are manufactured from fused siUca and fused quart2 because of the transmissive properties and high purity (222). 

Quartz also has modest but important uses in optical appHcations, primarily as prisms. Its dispersion makes it useful in monochromators for spectrophotometers in the region of 0.16—3.5 m. Specially prepared optical-quality synthetic quartz is requited because ordinary synthetic quartz is usually not of good enough quality for such uses, mainly owing to scattering and absorption at 2.6 p.m associated with hydroxide in the lattice. 

An example of a serial-recording EEL spectrometer is shown in Eig. 2.33 it features a magnetic prism system which was constructed for a TEM/STEM of the type JEOL JEM lOOS [2.199, 2.200]. Its second-order aberrations are corrected by curved pole-piece boundaries, an additional field clamp, and two extra hexapoles acting as stig-mators. The electron beam can be adjusted relative to the optical axis by use of several deflection coils. A magnetic round lens is positioned just in front of the prism to... 

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