Reflector array

Fig. 17. Agilent reflector array operation. Millimeter-wave reflector array panel alters the phase of the transmitted wavefront to allow high-speed digitally controlled focusing over a range of target voxel locations...

For comparison, the frequency response of a two-port SAW resonator is shown in Figure 6.11 (page 364). Note that it resembles the response of the delay line, with the addition of a sharp spike, where the insertion loss is considerably lower, at the center of the pass band. The similarity of the delay line and resonator frequency responses is a consequence of both devices using the same transducer pattern, while the spiked region of much lower insertion loss is a result of the ridge-reflector array utilized to set up a standing wave. Unlike the highest point of the delay-line spectrum, there is no 6-dB theoretical insertion loss limit for the peak of the resonator spectrum — loss can approach 0 dB. 

The graphite CSS and PSR are required to maintain geometry of the core and reflector array in order to assure capability to shut down the reactor and to provide convection and/or conduction heat paths for the removal of heat. Conditions of potential structural consequence to performance of these... 

As any conventional probe, acoustic beam pattern of ultrasound array probes can be characterized either in water tank with reflector tip, hydrophone receiver, or using steel blocks with side-drilled holes or spherical holes, etc. Nevertheless, in case of longitudinal waves probes, we prefer acoustic beam evaluation in water tank because of the great versatility of equipment. Also, the use of an hydrophone receiver, when it is possible, yields a great sensitivity and a large signal to noise ratio. 

Multicavity filters. Multicavity Fabry-Perot filters are used to make very narrow transmission filters. A simple Fabry-Perot cavity (see Ch. 2) consists of a halfwave layer surrounded by two reflectors of typically 10 layers each. Figure 4 shows three transmission profiles obtained with one, two or three cavity filters. The three cavity HL) 5HH(LH) 5) " 3 filter has a 1.2 nm bandwidth. It has 60 layers. Note that the three-peak top of the transmittance. Each cavity has to be well adapted to the following one if not the resulting transmittance can be very poor. Such cavities are broadly used in telecoms in between arrays of antennas for cell phones. 

Other potential applications of photonic crystals include crystals with rows of holes to guide radiation around sharp bends (something that cannot be attained with conventional optical fibres), nanoscopic lasers formed from thin films, ultrawhite pigment formed from a regular array of submicron titanium dioxide particles, radio frequency reflectors for magnetic resonance imaging (MRI) and LEDs. 

Figure 6. Diagram of LPA instrument. The reflector is at a distance of up to 5 km from the rest of the instrument. The slotted disk-photomultiplier (PM-S.DISC) has been replaced by a diode array. (Reproduced with permission from reference 38. Copyright 1984.)...

Figure 1 is a schematic diagram of the experimental setup. The test section is a horizontal rectangular channel 40 mm in height (H), 160 mm in width (W), and 6,000 mm in length (L). The rectangular channel is completely constructed of transparent acrylic resin, as shown in Figure 2. Tap water and air are used as the gas and liquid phases, respectively. Water is circulated by a 2.2 kW pump fed by a water reservoir 4.2 m away. Air bubbles are injected into the horizontal channel from the upper inner surface of the channel. An array of capillary needles produces bubbles 10-100 mm in length. Before the air and water are mixed, their volumetric flow rates are measured. After leaving the horizontal channel, the gas-liquid mixture is dumped into a tank that acts as a bubble remover when the liquid phase is recirculated it is free of bubbles. At the end of the horizontal channel tracer particles are added to the water to act as ultrasound reflectors. The mean particle diameter is 200 pm and the particle density is 1020 kg/m3. These tracer particles are assumed to...

Passive FPAs are perhaps the most familiar imaging system architecture because this architecture is used for most optical and IR cameras. In this configuration, an array of small detectors is placed at the focal plane of a lens or reflector system. The received energy in this case is derived from thermal (black-body) emission or reflected radiation from the scene. Thermal emission near room temperature peaks in the long-wave IR... 

A simple light scattering photometer was designed, to measure the angular distribution of intensity of scattered, polarized, He/Ne light, by micron and sub-micron particles [186]. The photometer used an ellipsoidal reflector and simple optical components to collect the scattered light and focus it on a 512 element photodiode array. 

Reflectron Ion Optics. The reflectron, or ion reflector. compensates for changes in flight time associated with ions of the same m/% ratio that have different kinetic energies [60-62]. This correction is made after ion extraction. A reflectron consists of an array of electrostatic lenses, at the opposite end of the drift tube, to which is applied a DC voltage gradient of the same polarity as the extraction... 

The low-index layer is perforated by many small ohmic contacts that cover only a small fraction of the entire area. The array of microcontacts allows the electrical current to pass through the dielectric layer. Assuming that the ohmic contacts have an area of 1 % of the reflector, and that the alloyed ohmic contact metal is 50% reflective, the reflectivity of the ODR is reduced by only 0.5%. The ODR described here can be used with low-cost Si substrates or metal substrates using conductive epoxy or a metal-to-metal bonding process. These bonding processes have much less stringent requirements than direct semiconductor-to-semi-conductor wafer bonding processes. 

Fig. 1.19 Schematic of the omnidirectional reflector (ODR) LED. An array of microcontacts perforating the ODR serves as p-type ohmic contact to the epitaxial AIGalnP layers.

Array (Solar) - Any number of solar photovoltaic modules or solar thermal collectors or reflectors connected together to provide electrical or thermal energy. 

Hemispherical Bowl Technology - A solar energy concentrating technology that uses a linear receiver that tracks the focal area of a reflector or array of reflectors. 

Power (Solar) Tower - A term used to describe solar thermal, central receiver, power systems, where an array of reflectors focus sunlight onto a central receiver and absorber mounted on a tower. 

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