Analyzing rotator prism

Optical emision spectra nowadays are simply measured using a fiber optic cable that directs the plasma light to a monochromator, which is coupled to a photodetector. By rotating the prism in the monochromator a wavelength scan of the emitted light can be obtained. Alternatively, an optical multichannel analyzer can be used to record (parts of) an emission spectrum simultaneously, allowing for much faster acquisition. A spectrometer resolution of about 0.1 nm is needed to identify species. 

An equally accurate measurement of the phase difference is obtained when a quarter wave plate is introduced between rotor unit and analyzer in the usual way (extinguished between the crossed polarizing prisms). As is well-known, this quarter wave plate transforms the ellipticity of the light-wave emerged from the rotor unit into a rotation according to the simple relation ... 

A few words should be said with respect to the principle of the measurement. In order to determine extinction positions, the plane of polarization of the incident beam is adjusted so that it coincides with the plane of incidence of the mirror (reflection prism). The analyzer, which is placed in the line of the horizontal beam A, is then crossed. This analyzer is placed on an arm, which extends from a vertical tube containing the polarizer. This tube is mounted revolvable around the incident beam. Handle in Fig. 6.6 is also connected with the said hinging arm, in order to make part V, which contains the mirror, rotating together with the polarizer. As a consequence, the planes of polarization and of incidence remain coincident during this rotation. No difficulties are encountered in this way with the determination of the extinction positions. A slight incon-... 

The Brinkman Model 2010 analyzer (figure 9.16) scans the sample with a shaped and focused laser beam using a rotating wedge prism. The time... 

Fig. 6 The Galai particle-size analyzer uses a laser beam and a rotating wedge prism to measure the size of fine particles by the length of time the fine particle blocks the light reaching the photodetector. (A) Basic layout of the Galai instrument (B) the laser beam traces a circular path within the sample cell, and the logic of the instrument rejects any particles that are off-center or out of focus (C) the length of time that the laser beam is blocked is related to the size of the fine particle. (From Ref...

FIGURE 5.13. Crossed Nicol prisms, (a) No crystal, (b) an isotropic crystal between the polarizer and the analyzer and (c) an anisotropic crystal which rotates the plane of plane polarized light to some extent as shown. 

Thus, the polarization of both the incident and scattered light must be controlled. A typical argon laser produces linearly polarized light. The incident polarization can be adjusted to be either vertical or horizontal with respect to the scattering plane with a double Fresnel rhomb polarization rotator. The scattered light can be analyzed with a Glan-Thomp-son prism polarizer. 

Polarizing microscope n. An optical microscope fitted above and below the specimenholding stage with nicol prisms or polarizing filters. The lower filter (polarizer) imparts plane polarization to the incoming hght. The upper one (analyzer) is rotatable, but is usuaUy set so that its plane of vibrations is at 90° to that of the lower one. With isotropic specimens, ah hght is... 

The angle through which the analyzer prism must be rotated in this experiment is called a, the observed rotation. It is equal to the number of degrees that the optically active substance rotated the beam of plane-polarized light. If the analyzer must be rotated to the right (clockwise), the optically active substance is said to be dextrorotatory ( + ) if rotated to the left (counterclockwise), the substance is levorotatory —... 

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