Optical depth method

Cemi used spectral transmission and extinction using UV, visible and near IR to measure slurry particle size distributions with undiluted continuous flow [347]. The method uses multiple linear detector array spectrometers. It also uses multiple sample cells of different optical depths optimized for a specific spectral range, multiple optical paths and multiple linear detector arrays. 

The presence and distribution of phytoplankton in the sea is determined primarily by the abundance of chlorophyll. Although this is not a direct measure of the number of cells, because they contain different amounts of chlorophyll under different conditions, it is the most rapid and widely used method of identifying the presence of photosynthetic organisms. Because the color of the ocean can be determined by satellites, it is possible to determine the global content of chlorophyll in the sea over one optical depth, about the first 30 m of surface waters. 

ATR-FTIR spectroscopy is an optical depth profiling method in which a concentration or structural gradient is probed near the surface of a material, such as an adhesive, sealant or coating. Recently, a number of improvements have been made in the method (192). 

Tissues such as skin have also been studied using photothermal methods, especially IR radiometry, which is capable of noncontact measurement, and is robust to alignment instabilities. In addition to the thermal and optical depth profiling of the various layers of the skin, photothermal spectroscopy has been used to study the time-dependent penetration of topically applied cosmetics and sunscreens below the skin surface. Photothermal studies have been used to monitor the time for which a topically applied film exists as a discrete phase on the outer surface of the skin. 

During the optical coat work stress examination method the upper plate of the head of some of the bolts was covered with an optical coat work (Fig. 4). On the head of some other bolts strain gauges were stuck which measured the plain biaxial stress state in the middle of the top surface of the head of the bolt (3.5 x 3 mm). The magnetic probe detected average stresses up to 0.1 mm depth in an area of 14 mm diameter in the middle of the head of the bolt. 

Another basic approach of CL analysis methods is that of the CL spectroscopy system (having no electron-beam scanning capability), which essentially consists of a high-vacuum chamber with optical ports and a port for an electron gun. Such a system is a relatively simple but powerful tool for the analysis of ion implantation-induced damage, depth distribution of defects, and interfaces in semiconductors. ... 

Independent of depth profiling considerations, SNMS provides a powerful bulk analysis method that is sensitive and accurate for all elements, from major to trace element levels. Since SNMS is universally sensitive, it offers obvious advantages over elementally selective optical methods. 

The basis of Method II may be deduced from Figure 6-3. To do this, let us consider the ideal case, in which the x-rays involved are monochromatic, all influences of composition are absent, the simplest x-ray optics obtain, and excitation of a characteristic line in the film by a characteristic line of the substrate does not occur. Suppose now that a beam of intensity Iq falls upon a metal film d cm thick to excite a characteristic line of intensity Id- The contribution to Id of a volume element of constant area and of thickness dx, located at depth x, is... 

In the earliest SFG experiments [Tadjeddine, 2000 Guyot-Sionnest et al., 1987 Hunt et al., 1987 Zhu et al., 1987], a first-generation data acquisition method was used, and, because of the limited signal-to-noise ratios, IR attenuation by the electrolyte solution was a substantial handicap. So, in earlier SFG studies, as in IRAS studies, measurements were performed with the electrode pressed directly against the optical window [Baldelli et al., 1999 Dederichs et al., 2000]. With the in-contact geometry, the electrolyte was a thin film of uncertain and variable depth, probably of the order of 1 p.m. However, the thin nonuniform electrolyte layers can strongly distort the potential/coverage relationship and hinder the ability to study fast kinetics. 

Results In the first series of our experiments, we studied the capabilities of optical methods to visualize internal structures of plants. OCT images of the plant show the capability of OCT to identify tissue structures at depths of 1.5-2 mm. Individual cells are clearly distinguished due to the difference in scattering properties of their structural elements. Cellular walls, for instance... 

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