Laser polarimetry

Other diagnostic tests scanning laser polarimetry, confo-cal scanning laser ophthalmoscopy, and optical coherence tomography. 

Limits of detection for many amino acids were enhanced considerably by pre-column derivatization with the achiral reagent dansyl chloride whose function it was to increase their specific rotation [17]. Determinations of the enantiomeric purities for mixtures of D-and L-tryptophan [18] and of isomeric ratios for mixtures of pseudoephedrine and its diastereomer ephedrine [19], were effected using diode-laser polarimetry and using OR detection in series with UV absorbance detection respectively. 

Scanning laser polarimetry (GDx VCC) (Carl Zeiss Meditec, Inc.)... 

Confocal scanning laser ophthalmoscopy, ocular coherence tomography, and scanning laser polarimetry seem to be similarly able to discriminate between healthy and glaucomatous eyes. 

Scanning laser polarimetry measures the change in the polarization state of an incident laser light passing through the naturally birefringent nerve fiber layer to provide indirect estimates of peripapillary nerve fiber layer thickness. 

The strong influence of the surface conditions on the emissivity and lack of information in the literature concerning pre-treatment make it difficult to interpret emissivity data. An overview of emissivity measurements for W, Nb, and Ta at 684.5 nm from 1500 °C up to the liquid phase using laser polarimetry is given in [1.130]. 

To be effective, the light sources used for chiroptical detection systems must have an intensity that is much greater than those ordinarily used in polarimetry. This comes about because the angular rotations observed for the very low analyte concentrations and very short sample pathlengths typical of an analytical liquid chromatograph, are extremely small (mdeg. and less). Conventional light sources have been replaced with laser illumination but these are not without problems, a major one of which is the instability in the emission [23],... 

Polarimetry detectors are applied to detect optically active components. The emitted linearly polarized light is rotated by optically active components in the eluent stream and the angle of rotation is detected. Since the introduction of these detectors, which use laser light as the light source, the drawback of low sensitivity has been overcome. Similar to the DAD detectors for the UV range, circular dichroism (CD) detectors are available to detect the CD spectrum of substances. Such detectors are, so far, not widely used in preparative chromatography. 

In the following I want to attempt a sort of unification of different sources of optical rotation and dichroism and show that far from being a narrow specialist s area of laser spectroscopy it is an enormously rich and varied field of study. I will therefore take as my starting point the famous and well-known dispersion relations and develop from these the form of the Faraday, Stark and PNC optical rotation. I shall also consider very briefly the extension of these ideas to the case of Doppler-free polarimetry and later I shall discuss how the use of lasers themselves brings in a variety of problems, in particular that of saturation. Finally, I will say something about the form of the weak interaction in so far as it enters the atomic Hamiltonian as a weak (no pun really intended ) perturbation. 

Lasers represent a special type of light source [16], [21], [60], [61]. They are used in trace analysis by fluorescence measurement or laser-induced fluorescence (LIF) (- Laser Analytical Spectroscopy) [62] - [64], in high-resolution spectroscopy, and in polarimetry for the detection of very small amounts of materials. Lasers can be of the gas. solid, or dye type [21]. In dye lasers, solutions of dyes are pumped optially by another laser or a flash lamp and then show induced emi.s-sion in some regions of their fluorescence bands. By tuning the resonator the decoupled dye laser line can be varied to a limited extent, so that what may be termed sequential laser spectrometers can be constructed [65]. In modern semiconductor lasers, pressure and temperature can also be used to detune the emission wavelength by 20-30nm [66], [67]. 

Noninvasive techniques include infrared, Raman spectroscopy, polarimetry, l ht scattering, photoacoustic spectroscopy, polarization technique, and impedance. In infiared spectroscopy, absorption or emission data in the region of spectrum are compared to known data for glucose. In Raman spectroscopy, laser light is used to... 

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