Transducers photodiode

Diagnostics Smoked foil, piezoelectric, pressure transducers, photodiodes, ion detectors, fast response thermocouples, gas sampling, and gas chromo to graphy Smoked foil, piezoelectric pressure transducers, photodiodes, ion detectors, fast response thermocouples, gas sampling, and gas chromotography ... 

Active matrix addressing can also be used in printer heads [628] and linear sensor arrays [629]. a-Si H TFTs are used to address a linear array of output or input transducers, respectively. In the linear sensor array, u-Si H photodiodes are used. 

Optocouplers are a class of devices with input current (/ ) and output current (70) coupled optically, but isolated electrically. They are used extensively in the automation industry and in laboratory equipments where large common-mode noise/voltage or hazardous electrical shocks are present in circuits between transducers detectors and controlling equipments. The simplest optocoupler is composed of an LED (input) and a photodiode (output) as shown in Figure 1.19. 

Fig. 2.23. Schematic diagram of the laser flash photolysis/UV absorption spectroscopy apparatus employed by Slagle et al. [57] to study reaction (32) at higher pressures. B, Baratron pressure transducer, PS, flow sensor I, iris L, lens NV, needle valve to control total pressure PD, photodiode PM, photomultiplier V, solenoid valve Zn, zinc lamp for...

Fig. 1.1 (a) Schematic diagram of contact mode AFM and SEM images of (b) V-shaped AFM cantilevers and (c) tip. The basic elements of transducer (piezo positioner), cantilever and tip assembly, and ultrasensitive force detection system (optical beam deflection/photodiode detector) are common for most AFM techniques, while details may differ (reproduced with permission from [4])... 

Classical transducers such as the photomultiplier tube and the photodiode have been used in most the flow systems [96,97], Since the 1980s, the tendency to use diode array spectrophotometers has increased, mainly for simultaneous determinations [98] and/or for implementing dual wavelength spectrophotometry [99], the latter being more exploited in segmented flow analysis. 

The evolution of the detonation wave is monitored by using high-speed piezoelectric pressure transducers and photodiodes mounted along the tube at identical axial positions. Throughout the experiments, the level of nitrogen dilution,... 

Siiicon Photodiode Transducers A silicon jiholodiode transducer consists of a reverse-biased pn junction formed on a silicon chip. As shown in Figure 7-32, the reverse bias creates a depletion layer lhal reduces the conduelance of the junction lo nearly zero. If radiation impinges on the chip, however, holes and electrons are formed in the depletion layer and swc rl through the device lo produce a current lhal is proportional lo radiant power. They require only low-vt)liage power supplies or can Ire operated under zero bias and so can be used in portable, battery-powered insirumenis. 

In a PDA, the individual photosensitive elements are small silicon photodiodes, each of which consists of a reverse-biased pn junction (see previous section). The individual photodiodes are part of a large-scale integraled circuit formed on a single silicon chip. Figure 7-3.1 shows the geometry of the surface region of a few of the transducer elements, F.ach element consists... 

Figure I3-I6b is a schematic representation of a double-beam photometer used to measure the absorbance of a sample in a flowing stream. Here, the light beam is split by a iwo-branched (bifurcated) fiber optic, which transmits about 50% of the radiation striking it in the upper arm and about. 50% imho lower arm. One beam passes through the sample, and the other passes through the reference cell. Filters are placed after the cells before the photodiode transducers. Note that this is the double-bcam-in-spacc design, which requires photodiodes with nearly identical response. The electrical outputs from the two photodiodes arc converted...

The linear photodiode array (LPDA) is a transducer developed to enable simultaneous measurement of light intensity at many wavelengths. The diode array consists of a number of semiconductors embedded in a single crystal in a one-dimensional linear array. A common procedure is to use a single crystal of doped silicon that is an n-type semiconductor. A small excess of a group 3A element, such as arsenic, is embedded into the surface at regular intervals. This creates local p-type semiconductors. The semiconductor device ideally has a cross-section such as that shown in Fig. 5.24. The surface contains a linear series or array of pn junctions, each of which is a photodiode. The individual diodes are called elements, channels, or pixels. 

Table 14.5 Comparison of avalanche photodiodes an photomultilpier tubes as signal transducers.

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