Optical sensing system

Vast majority of the optical sensing systems are of the modulation type and its functional structure can be sketched as in Figure 1. 

Many integrated optical sensing systems have been designed, realized and tested in the laboratories but only a few of them have reached the market. 

Optical fibre based optical detection systems offer a number of advantages over bulk optical sensing systems. The principal one is that a robust passive sensing head may be remoted from the monitoring station a factor giving particular advantages in severe environments. This also allows... 

Preliminary research has shown that Brillouin fiber-optic sensing systems provide a possible method to detect leaks and third-party intrusion on a pipeline over distances of 25 km or more. Their intrinsic response to both temperature and mechanical strain allows for the separation of these parameters and the detection of anomalies in the scan profiles. In addition, the same sensor could be integrated into the pipeline system to detect possible ground movement relative to fixed reference points. Limited test results on surface loads associated with the intrusion of vehicles and people on a pipeline have demonstrated the sensitivity of the system and its ability to discriminate loads at different soil depths. 

Metal nanoparticles have extraordinary size-dependent optical properties, not present in the bulk metal and have, consequently, been the subject of intense research during the past decade or so.27 Attention has recently focused on functionalising colloidal nanoparticles with molecular recognition components for potential sensing applications.28,29,30 We have prepared a new amido-disulfide functionalised zinc metalloporphyrin (8) which was self-assembled on to gold nanoparticles to produce a novel anion-selective optical sensing system (9) (Scheme 3).4... 

The combination of LSPR with interferometry on a PAA layer chip enabled two important aspects of optical sensing systems a shift in and an increment in the absorbance intensity in a new and highly sensitive format. The excitation of optical characteristics and the detection were performed using an optical fiber, which made our aptasensor user friendly and suitable for the simple construction of a handheld diagnostic device. 

The most commonly used method for detecting metal ions is inductively coupled plasma mass spectrometry (ICP-MS). A Tiile comprehensive in both selectivity and sensitivity, ICP-MS often requires complicated instrumentation and sampling, which are known to be the major drawbacks of the technique. To overcome such limitations, several detection methods based on nanotechnology have recently been developed for metal ions. In particular, the unique properties of DNA-AuNPs such as programmable assembly and their optical properties have made them attractive for utilization in optical sensing systems. In this section, several optical sensing systems for metal ions based on DNA-AuNPs are discussed. 

In particular optical sensing systems belong to this group, which are described in detail in Chapter 27. For example, fluorescent reporter groups are incorporated into the MIP, the properties of which are altered upon analyte binding [14-16]. A very sensitive sensor for a hydrolysis product of the chemical warfare agent Soman has been described based on a polymer-coated fiber optic probe and a luminescent... 

Figure 3.3 shows the outlines of the optical sensing system for contact mode AFM and LFM. 

A Fabry-Perot (FP) interferometer can be used in an optical sensing system to pass a specific part of the spectrum, functioning like a monochromator. An FP structure is the most suitable for passband optical filters. A Fabry-Perot optical filter consists of two parallel mirrors with a resonance cavity in the middle (Fig. 2). The equation 7u = 2nd shows its operation principle, where n is the refractive index of the cavity medium, d the cavity length, X the incident wavelength, and q the interference order q = 1,2,3,...). 

In optical sensing system, it is necessary to employ optical couplers and lenses in order to focus the light beam to the optical fiber and direct radiation from the return fiber to the photodetector. Injecting light from a source into a fiber is a more tedious operation. Laser sources produce a coherent beam of light with a cross-section almost equal to the cross-sectional area of the optical fiber, and, therefore, can be coupled very efficiently to the fiber. On the... 

Transducers for optical sensing systems in chemical and biochemical sensors have also been developed based on the sensitivity of surface plasmon resonance (SPR) devices. Since first described in 1983 [195], SPR transducers have been used in many different applications, including immunoassays [195], [196] and sensors for... 

B. Kuswandi, Nuriman, J. Huskens, W. Verboom, Optical sensing systems for microfluidic devices a review, Analytica Chimica Acta 601 (2007) 141-155. 

Planar waveguides, the photonic wires for on-chip optical signal transmission, constitute the basic building block for the vast majority of planar optical sensing systems [16]. Examples of commonly used waveguide-based sensor devices include microresonators, interferometers, and waveguide gratings. 

Kuswandi B., Nuriman, Huskens J., and Verboom W., Optical sensing systems for microfluidic devices A review. Ana/. Chim. Acta, 601,141-155 (2007). 

Other technologies that have been used for atmospheric corrosion sensing include electrical resistance (ER) sensors and more recently fiber-optic sensing systems. Additional information may be found on this topic in Chap. 6, Corrosion Maintenance Through Inspection and Monitoring. 

Optical Sensing System and Gas Sensing System Design Considerations... 

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