Glasses optical identification

The NIST material SRM 1866a consists of a set of three common bulk mine-grade asbestos materials chrysotile, amosite and crocidolite, and one glass filter sample. SRM 1867 consists of a set of three imcommon mine-grade asbestos materials antophyllite, tremolite and actinohte. The optical properties of SRMs 1866a and 1867 have been characterized so that they may serve as primary calibration standards for the identification of asbestos types in building materials. 

Equilibrium Phase Behaviour. Phase studies were performed using approximately 10 g samples of oil-surfactant mixture diluted sequentially by the weighed addition of water. The initial binary mixture contained 5-70 w/w surfactant at 5 intervals. Phase boundaries were determined to + 0.5 water. The ternary mixtures in Pyrex glass tubes fitted with PTFE lined caps were equilibrated to the required temperature (20-65 0.1°C) for 2 hours and then thoroughly mixed for 5 minutes using a Fisons orbitsil whirlimixer. The tubes were then returned to the waterbath and left undisturbed for 48 hours before identification of the phase type using a crossed polarised viewer and an optical microscope. 

Measuring Raman spectra of polymorphs requires little or no sample preparation. Spectra can be measured from single crystals and from powders. Moreover, samples can be contained in glass capillaries or mounted on a goniometer. As mentioned earlier, fiber optics can be used to interface the instrument with the samples. Thus the measurements are straightforward and easy to perform, whereas the analyses produce information on structures and spectral fingerprints for straightforward identifications. 

Identification of different blood cell types is normally carried out using light (optical) microscopy. Blood cells are collected and are either fixed or spread alive on glass slides and then examined microscopically. Many types of blood cells have been identified, and relative numbers and types of cells have been found to differ among tunicate species. Tunicate blood cells are fragile and readily change appearance. It is possible that some commonly accepted blood cell types may actually be artifactual. 

The fact that Raman measurements can usually be made through glass and plastic packaging, eliminating the need to prepare samples prior to analysis, makes Raman spectroscopy very attractive for forensic science. The availability of commercial portable instramentation and extended fiber optic probes makes Raman suitable for on-site forensic use, minimizing the risk of exposure of investigating personnel to potentially hazardous chemicals. Eor identification of explosives the SERS method has proved to be very useful. A tiny amount of explosive, diluted... 

Incompatible polymer mixtures can be recognized, in many cases, by purely optical means, such as the opaque appearance in the solid state. On the other hand, transparent samples are not a guarantee of compatibility of two polymers, since an opacity only occurs for sufficiently large refractive index differences between regions of sufficient size (see also Section 14.3). Consequently, incompatibility in transparent samples may require identification by electron microscopy. If the regions of pure polymer in the polymer mixture are of sufficient size, two different glass-transition temperatures can often be measured. In the case of incompatibile polymer mixtures, such different glass-transition temperatures remain invariant with the composition of the mixture. 

Examination of specimens in UV light requires the use of optical components capable of transmitting such short wavelengths, which means the use of quartz rather than glass lens components. However, when combined with a UV spectrophotometer, this enables the analysis of small areas of a sample by UV reflectance, absorption, or transmission. An example of this is the identification of materials used by the artist in a painting. The use of UV microscopy for enhanced resolution has been entirely superseded by transmission electron microscopy. 

Chemical analysis techniques permit us to analyze molecular composition and molecular weight to allow us to characterize plastics precisely. Physical methods allow us to look at the behavior of plastics in response to a variety of influences such as temperature, pressure, and time. This understanding helps us to say how the plastics will behave in their lifetime. Plastics analysis may include identification and chemical composition, thermal properties, mechanical properties, physical properties, electrical properties, and optical properties, among others. Chemical analysis may include material identification and characterization by techniques including FTIR, NMR, GC, GC/MS, HPLC, and GPC. Thermal analysis does provide information such as melting point, glass transition, flash point, heat deflection temperature, melt flow rate, and Vicat softening point. Mechanical properties, on the other hand, provide critical information such as tensile... 

Optical fibers can be plastic, i.e. methacrylate, or inorganic, i.e. glass for the visible spectral region and quartz for the UV region and range from 8 to 1000 pm in diameter. Some manufacturers use color codes to facilitate their identification (Figure 5.11) [2]. 

---