Testing optical characterization

Due to diffraction effects of micron-sized mirrors in a regular array, commonly used techniques for surface characterization based on interferometry are inefficient. To overcome the diffraction effects we have developed a novel surface characterization method with an incoherent light source, based on the Foucault s knife-edge test (Zamkotsian and Dohlen, 1999). Since Leon Foucault introduced the knife-edge test in the last century (Foucault, 1859), it has been widely used for testing optical surfaces (see Ch. 3). The test offers a simple way of obtaining easily understandable, qualitative information of the surface shape. 

Modifications of the fuel injectors of an advanced combustor were made to permit spatial control of individual fuel-injection sites. Miniature fuel delivery valves were developed and flow bench was tested to characterize the valve flow characteristics. Optical sensors and a translating gas sampling rake are being integrated in an experimental rig to evaluate the level of pattern factor control at the combustor exit. The CFD simulations were run, and the results will be validated with data that will be acquired from the forthcoming APFC experiments. The numerical solutions will then be used to develop control algorithms that will be used for future closed-loop APFC experiments. 

Since many gemstones appear quite similar, which is why they can be simulated, it is important to be able to distinguish the real from the synthetic or from the simulant. If you have a scanning electron microscope (SEM) with XEDS available, the latter task is not a problem, but this is usually not the case in the field (or the shop). The basic tests are thermal conductivity, optical properties, and mechanical properties. Using a mechanical test to characterize a material that you do not want to damage is clearly tricky, so the use of hardness measurements is directed more toward minerals than gemstones. 

Microscopy test. The optical microscope is a very useful tool in fiber testing and characterization laboratories. It is easier to identify natural fibers than synthetic ones because of the similarity in synthetic fiber appearance. Shape and cross section are common characteristics to examine under the microscope. Polyolefin fibers are usually characterized by a smooth and round cross section. Microscopy is not a definite technique to distinguish between PE and PP fibers. Microscopy is effective in telling whether the fiber is a mono-component filament or a bicomponent filament where two polymers are extruded in a sheath-core configuration. 

The polymer network structure can be studied by various means. Optical characterization is particularly versatile, since it can probe the composites directly and test whether, and to what degree, the network is oriented (75, 27, 30, 31), Hot-stage cross polarized light microscopy can be used to test the influence of monomer or polymer on LC phase transitions of these composites. Measurement of the birefringence of the bare polymer network, or of the LC composite in the isotropic state, yields information concerning anisotropy of the polymer network and of the type and strength of interaction between the network and LC matrix (75, 27, 30, 31). 

Test bar characterization. The injection-molded test bars are characterized by optical microscopy and by differential scanning calorimetry (DSC). Light microscopy is carried out in a Zeiss Axioplan 2 equipped with an AxioCam camera. The specimens are cross-sections cut from the centers of the test bars. They are 10 p,m thick. Slicing is carried out at -70 °C using a rotary cryo-microtome Leica RM 2165. A Mettler-Toledo DSC 82 P is employed. Sample mass is 5.0 0.1 mg. The samples are studied under nitrogen flux, cooled to —100 °C and heated to 280 °C at a rate of 20K/min. 

Eichhom, W. L. Magner, T. J. (1986). Large aperture, freestanding wire grid polarizers for the far-infrared fabrication, characterization, and testing. Optical Engineering, 25, 541-4. 

Tables 4—6 Ust ASTM methods used for the characterization of PB and PMP. A number of specialized methods were developed for testing particular articles manufactured from polyolefins several of these determine the performance of PB and PMP film, including the measurement of the film s dart impact strength and tear strength. Dart impact strength is measured by dropping a heavy dart with a round tip on a stretched film. Tear resistance, which reflects the film s resistance to tear propagation, is measured with the Ehnendorf tear tester. Two values for the tear strength are usually reported, one in the machine dkection of the film and the other in the transverse dkection. Pipes manufactured from PB are tested by pressurizing them internally with water the time-to-burst failure is determined at various temperatures (46). The standard test method for haze and luminous transmittance (ASTM D1003) is used for the measurement of PMP optical characteristics.

Polarized light photomicrographs were taken of the green and calcined cokes, as well as their corresponding test graphites. The untreated extract cokes are characterized by very small amsotropic domains on the order of 3 microns or less. This type of optical structure is believed to be highly desirable for nuclear graphite applications. 

Experimental measurements to test these remarkable theoretical predictions of the electronic structure of carbon nanotubes are difficult to carry out because of the strong dependence of the predicted properties on tubule diameter and chirality. Ideally, electronic or optical measurements should be made on individual single-wall nanotubes that have been characterized with regard to diameter and chiral angle. Further ex-... 

After an optics has been coated, several tests are done to characterize its performances. They are briefly discussed in the following paragraphs. 

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