Point illumination

Third, it shows that a kind of psychic causality—or free will if you will—operates in conjunction with brain physiology. This last point illuminates the others and is so important as to deserve critical analysis. In the section that follows I consider the possible brain basis of lucid dreaming and develop a cognitive neuroscience theory applicable to all dissociative states where suggestion plays an important part. 

Fig. 4. Iseli melting point apparatus, with metal block and uree-point illumination. Only the side lights are used until sintering begins, and then the rear light is turned on to permit close observation of the formation of a clear melt. The apparatus is also built with an electrical heating element.

While commercial Raman spectrometers collect the scattered light from a laser spot of size 1 pm at best and the Raman spectra also include information of sample regions above and below the focal plane, the implementation of confocal microscopy can improve the optical resolution and the depth of sharpness. The method leads to better image definition. Confocal microscopy means point illumination and that a small aperture is placed in the optical path so that only the scattered light located in a thin focus plane can reach the detector. The aperture-dependent spatial... 

Confocal microscopes provide particularly good spatial resolution. They are mainly used in Raman and fluorescence measurements. The basic idea of a confocal microscope is that all structures being out of focus are suppressed at the detector. This is achieved by point illumination and a pinhole in front of the detector. The optical layout of a confocal microscope is shown in Fig. 5.15. 

Two alternative methods of Raman imaging via global illumination and via point illumination in combination with confocal light collection were applied to the study of heterogeneous polymer systems. The spectral and spatial resolving power of the different techniques was estimated experimentally. The influence of the depth resolution on the Raman image of a defined sample structure was demonstrated in a mathematical simulation. Data are given for PE, PS, polyacrylate, and epoxy resins. 23 refs. 

Fig. 6.21 TEM gives overall illumination and SEM gives point illumination.

By combining Raman imaging with photoacoustic FT-IR and FT-IR microscopy three-dimensional maps of the heterogeneous degradation of epoxy and polyurethane films exposed to UV and water vapor were obtained [241]. Similarly, the phase separation in styrene/butylacrylate copolymers and latex films were analyzed [242]. Blakey and George used point illumination Raman mapping to investigate the surface of photooxidized PP with a lateral resolution of 1 im and successfully mapped the distribution of both oxidation products (Q ,/3-unsaturated ketones) and catalyst residues [239]. The distri-... 

Each of the methods laid out by Delhaye and Dhamelincourt has its advantages and disadvantages. The first two methods are based on microprobing (point illumination) and, as such, can be confocal, a concept that was implemented some time in the 1980s and will be described below. The second method multiplexes sample illumination in one dimension, which means that there is some time advantage over the first, when there is sufficient laser power available so that the illuminating intensity is not a limitation. The... 

L Markwort, B Kip, E Da Silva, B Roussel. Raman imaging of heterogeneous polymers A comparison of global versus point illumination. Appl Spectrosc 49 1411-1430, 1995. 

Figure 7.6 Point-to-point illumination for scanning along a line (a), a rectangular domain plane within one plane (b) and a rectangular box/cuboid (c).

A method to detect diffusion coefficients of single molecules in solution is confocal microscopy. A confocal microscope uses point illumination, which is achieved by a pinhole in front of the objective (in an optically conjugated plane to the sample). The illuminated voliune is in the order of 1 femtoliter and. 

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