Off-axis configuration

Fig. 3. Schematic configuration of (a) the 90° off-axis sputtering technique and (b) the system used to prepare multilayers.

Apart from the short beam shear test, which measures the interlaminar shear properties, many different specimen geometry and loading configurations are available in the literature for the translaminar or in-plane strength measurements. These include the losipescu shear test, the 45°]5 tensile test, the [10°] off-axis tensile test, the rail-shear tests, the cross-beam sandwich test and the thin-walled tube torsion test. Since the state of shear stress in the test areas of the specimens is seldom pure or uniform in most of these techniques, the results obtained are likely to be inconsistent. In addition to the above shear tests, the transverse tension test is another simple popular method to assess the bond quality of bulk composites. Some of these methods are more widely used than others due to their simplicity in specimen preparation and data reduction methodology. 

Figure 6. (Left) Schematic showing basic TEM configuration for off-axis electron holography and (b) photograph showing electron microscope suitably equipped for recording holograms of magnetic materials.

For low-viscosity liquids, bulk rotation of the liquid can be reduced with the use of vessels having a rectangular cross-section, with the lateral insertion of the stirrer into the vessel, and with the use of baffles. When the stirring is weak, bulk rotation in cylindrical vessel can also be prevented by installing the stirrer off-center and/or at an angle to the axis, configurations resulting in an uneven mechanical stress on the stirrer shaft. 

Figure 6.6. 180° configurations using reflective optics based on an off-axis paraboloid (OAP). Upper drawing shows a hole in the OAP, lower drawing assumes laser and collection axes have been combined, as in Figure 6.4A, 6.5C, or 6.5D. 

It should be pointed out that, in good part because of the use of large off-axis mirrors, optical aberrations can lead to significant curvature of the images under certain instrumental configurations. This has a detrimental impact on spectral resolution when multiple rows are birmed. Pelletier et al. have reported a data processing procedure to minimize this effect for situations where experimental limitations prevent improving the optical set-up [9]. In future commercial... 

Specimens of dimensions 165mm X 19mm were cut from the panels with the fibers at 10 off axis. When tested in tension, this configuration is sensitive to changes in interfacial bonding (4). Following conditioning (described below) they were tested in tension in an Instron. The samples contained 33 3% resin as determined by resin burn off. 

Figure 7. Strength properties of composites V5. water content. A. 10° off axis test, (X) resin I, (- -) resin II, B. cross-ply specimens of resin III, (X) 0/90/0 configuration, (+) 90/0/90 configuration.

In the MIR, diffuse reflectance is very weak and could only be measured after routine FT-IR spectrometers became available (DRIFT spectroscopy, diffuse reflectance infrared Fourier-transform spectroscopy). Due to the lack of ideal non-absorbing scattering substrates in the MIR, the diffusely reflected MIR radiation is generally collected by large ellipsoidal mirrors, which cover as much area above the sample as possible. Two optical configurations are commercially available, on-axis and off-axis designs (Fig. 5.9). 

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