Optical detection devices

The excitation spectrum of a fluorescent material, i.e., the incident radiation spectrum required for the induction of fluorescence, is determined by the absorption spectrum of the fluorescent material, which it often closely resembles, and by the efficiency with which the absorbed energy is transformed into fluorescence. Normally, the excitation spectrum is of higher photon energy (shorter wavelength) than that of the corresponding fluorescence emission, and in sensor schemes this has an effect in the choice of preferred fluorescent agent, compatible with appropriate optical detection devices. 

This expression is the basic description for the use of the pyroelectric effect in a host of sensor applications including the well known optical detection devices (82,83). A particularly useful way of describing this type of system is with an equivalent circuit where the pyroelectric current generator drives the pyroelectric impedance and the measuring amplifier circuit as shown in Figure 11. 

The word chiroptical is descriptive of the techniques that use optical detection devices that are selective toward optically active (chiral) materials and/or molecules. They are used for structural investigation and analytical determination. There are three chiroptical techniques ... 

Figure 4.22 Principal function of an atomic force microscope, the tip of the cantilever is scanned across the surface and the change of the cantilever tip position by the attraction of the surface atoms is followed by an optical detection device.

Several new surface micromachining processes utilize the thick-fihn polymer SU-8 for fabrication of channels, wells, and other passive microfluidics that are integrated with electronics or optical detection devices. The development of actuation schemes and interconnect technologies may make integrated polymer microfluidic systems more attractive, although more research is needed for these components as well as the integration of the polymers with other materials to realize truly integrated systems. 

Vandaveer et al. [9] proposed anodic stripping voltammetry to measure fluids with ultrasmall volume. The advantages of this method are avoiding optical detecting devices, fast and easy, and suitable for irregular shapes of fluid flows. 

Such requirements are meant to change the usual configurations and technologies usually associated with photothermal set-up. These changes mainly affect the IR detection devices, the optical components associated with the excitation and detection flux and the signal acquisition hardware and software. Figure 9 presents a sketch of the so-called pre-industrial demonstrator built from those different improvements. 

Explosion Suppression With explosion suppression, an incipient explosion is detected and—within a few milhseconds—a suppressant is discharged into the exploding medium to stop combustion. Pressure and optical detection systems are used suppressors are pressurized and release the suppressants when actuated by an electroexplosive device. 

Optically detected magnetic resonance (ODMR) studies of -iT-conjugated polymer-based hght emitting diodes (LEDs) J. Shinar Organic Electroluminescent Materials and Devices, S. Miyata and H.S. Nalwa, Eds., Gordon and Breach, Amsterdam, pp.177-202... 

All spectrometers have the following basic units a source of electromagnetic radiation, a dispersion device, sample holder, optical devices for collimating and focusing, a detection device and a data readout or storage system. There are also a variety of ways in which these parts are assembled into the entire spectrometer. 

Optical properties of the material are less critical for microchips hyphenated with MS than for devices with on-chip optical detection where low background absorption or fluorescence is mandatory. Thus, completely opaque polymers like glassy carbon or polyimide " can be used as microfabrication substrates. Furthermore, polymer microchips are of great interest because their potentially low manufacturing costs may allow them to be disposable. Methods used for the fabrication of plastic chips include laser ablation and molding methods. 

Nemykin et al. (2007) found a similar direct reaction between ferrocene (FcH) and tetracyano-ethylene (TCNE). The formation of a spectroscopically detected [FcH]+ [TCNE] was established. Cyanoferrocene and tricyanovinylferrocene as major and minor products were obtained, respectively. Although tricyanovinylferrocene was not the sole product of this reaction and its yield was approximately 30%, the direct method of its preparation was an important step toward materials for optically limiting devices. Untill now, the highly toxic chloromercurioferrocene was used for the preparation of tricyanovinylferrocene (Nemykin and Kobayashi 2001). 

Banerjee, P., Banada, P. P., Rickus, J. L., Morgan, M., and Bhunia, A. K. (2005). A portable cell-based optical detetcion device for rapid detection of Listeria and Bacillus toxins. Proc. SPIE. 5996, 1-7. 

Liquid crystals have found widespread application in optical display devices as well as in detection of temperature uniformity and impurities. These properties are related to the orientational order of molecules in the temperature region between and the melting point. The possible applications of ferroelectric liquid crystals are promising. Superconductors (type II) can be used to create high magnetic fields at low power the ability of type I superconductors to trap magnetic flux within the domains of the normal material may also have applications. 

Optical-electronic devices of many kinds have been designed to determine the direction of weakly radiating remote objects by means of detection of their infrared emission, Detailed maps of the earth s surface can be made from aircraft at night by observing the varying infrared emission of the ground. For security, personnel can be detected in total darkness by infrared radiation. Such devices require ihe detection of low-level... 

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