Shadow device

To investigate gel formation and to detect any possible convective flows in a mixture under orbital flight conditions the researchers used a shadow device Pion-M , which provided synchronous photographs and temperature measurements of the examined object. 

The cuvette was placed in a light-tight rigid case to exclude incidental photoinitiation of reaction during storage and transportation. When designing the case a provision was made for its removal after installation of the cuvette in the shadow device Just before switching on the lamp. 

Therefore one might expect that in microgravity conditions the marked optical inhomogeneities caused by a strong convection would be fixed with the "Pion-M" shadow device, whereas small inhomogeneities caused by a weak motion would be detected with an interferometer after delivering the cuvette back to Earth. 

More predictable are the results of thermal measurements. The temperature curves (Figure 9) have the same form as the curves obtained in laboratory experiments under adiabatic conditions. An adequate heat contact of the cuvettes and the shadow device and an essentially decreased monomer concentration lower the temperature increase of the cuvette to 1.5 °C. The effect of already completed spontaneous polymerization also allows for the fact that the temperature maximum moves to the region of large times (under earth adiabatic conditions the temperature maximum is reached at t = 25 min). 

Figure 4.8. Current voltage curves for selected A1PO capacitor structures. A high-quality thermally oxidized Si02 dielectric in an identical structure is included for reference. Top contacts are 0.011-cm2 A1 dots thermally evaporated via shadow mask. Bottom contact is made via conductive substrate p++ Si in the case of 600 °C A1PO and Si02 capacitors, and sputtered Ta metal for 300 °C A1PO devices.

Fig. 13.10 (a) Tapered optical fiber. p0 is the initial diameter, inset schematic cross section of the device p is the waist diameter, L0 is the length of the waist, t is the maximum thickness of the palladium film (shadowed area) and X is radiation wavelength, (b) Time response of the sensor to periodic cycles from a pure nitrogen atmosphere to a mixture of 3.9% hydrogen in nitrogen, (c) Time response of a sensor when it was exposed to different hydrogen concentrations, (d) Transmission versus hydrogen concentration sensor parameters p 1,300 nm, L 2 mm, and t 4 nm. Reprinted from Ref. 15 with permission. 2008 Optical Society of America... 

Each of the techniques described above has unique strengths and weaknesses, and the optimum device structure for commercial full-color displays will also be heavily influenced by the ease with which it can be mass-produced. Currently full-color OLED displays have been manufactured commercially by using two of the above described techniques only, i.e., (a) side-by-side pixels deposited by high-precision shadow masking and (b) using white OLEDs and color absorption filters. 

In order to establish good electrical contact to the sensitive layer, it was necessary to coat the electrodes with a metal stack of Ti/W (diffusion barrier and adhesion layer) and Pt. The usage of a shadow mask during the metal deposition ensures full compatibility with other MEMS processing steps so that it is possible to fabricate various CMOS-MEMS devices on the same wafer. 

Professional photographers anticipate the instantaneous temporary shadow created by the flash itself and use various diffusers and backgrounds. These devices are also helpful for close-up shots of items. Special flash units that fit around the lens of some 35-mm SLR cameras are available to eliminate these shadows. 

Boy s Apporotus. A device for taking shadow photographs of projectiles in flight Ref Cranz, vol 3(1927),264... 

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