Optical sensor systems, components

Section 0 introduces the general concept of an integrated optical sensor system. This is followed by examples of implementations of the various components that make up an integrated sensor in Section 0. 

In summary, in this chapter we provided a general overview of the components of an optical sensor system. Specific implementations of the various components of this system have been presented and representative references to detailed descriptions of a number of sensor systems has been provided. The field of optical sensors for biological and chemical sensors continues to grow and remains focused on the development of low power, portable devices. 

In recent years, the evolution of the technological components required for IR sensor systems has been denoted by a significant miniaturisation of light sources, optics and detectors. Essentially, an IR sensor consists of (i) a polychromatic or monochromatic radiation source, (ii) a sensor head and (iii) a spectral analyser with a detector. As sensors where all optical elements can be included in the sensor head are the exception rather than the rule, also various optics, waveguides and filters may form essential parts of IR-optical chemical sensors. Another important building block, in particular when aiming at sensors capable of detecting trace levels, are modifications of the sensor element itself. 

Since the quality of a sensor and its application depends on all components of the sensor system, optical transduction, sensitive layers and chemometrics will be discussed in more detail in dependence on the different approaches. In the final chapter, quite a few applications will demonstrate the feasibility and the quality of such bio or chemosensors. Since miniaturisation and parallelisation are further essential topics in these applications, these approaches will be included. 

Studies of atmospheric properties using IR spectroscopy techniques have been reported in the literature for nearly 100 years. This paper presents a brief historical review of the development of this area of science and discusses the common features of spectrographic instruments. Two state of the art instruments on opposite ends of the measurement spectrum are described. The first is a fast response iri situ sensor for the measurement of the exchange of CO2 between the atmosphere and the earth s surface. The second is a rocketborne field-widened spectrometer for upper atmosphere composition studies. The thesis is presented that most improvements in current measurement systems are due to painstakingly small performance enhancements of well understood system components. The source, optical and thermal control components that allow these sensors to expand the state of the art are detailed. Examples of their application to remote canopy photosynthesis measurement and upper atmosphere emission studies are presented. 

Micro flow control devices open new possibilities for the miniaturization of conventional chemical and biochemical analysis systems. The micro total analysis system (pTAS) including microfabricated detectors (e.g. silicon based chemical sensors, optical sensors), micro flow control devices and control/detec-tion circuits is a practical micro electro mechanical system (MEMS). pTAS realize very small necessary sample volume, fast response and the reduction of reagents which is very useful in chemical and medical analysis. Two approaches of monolithic and hybrid integration of these devices have been studied. Monolithic and hybrid types of flow injection analysis (FIA) systems were already demonstrated [4, 5]. The combination of the partly integrated components and discrete components is useful in many cases [6]. To fabricate such systems, bonding and assembling methods play very important roles [7]. 

Fig. 7.8.2 shows the basic components of a camera system, and the signal flow. A vision system or optical measurement system consists of the elements illustrated in the figure. A lens collects radiation from a source, such as a light bulb or an illuminated object. A sensor converts the collected radiation into an electronic charge, which can be preprocessed by electronics. The preprocessed information is con-... 

The determination of the overall resolution of some measuring equipment may require more efforts, as it involves the combination of the resolution of different measuring system components. For example, the optical resolution of optical measuring systems may be calculated by the combination of the resolution of different components (e.g., their MTF - modulation transfer functions), such as lens resolution, sensor resolution, data transmission resolution, and display resolution. 

An important part of this technology is the pressure-temperature optical monitoring systems (OMS). They are responsible for acquiring physical data (pressure and temperature) from the downhole environment of oil industries. OMS availabiUty analysis, mainly of the sensor component, is already done by Droguett etal. (2008). Moreover, Moura ei a/. (2008) developed optimal time maintenance poUcies for OMS systems. 

The basic instrumentation associated with photometric sensors is simple and requires both optical and electrical components. Apart from the optical fiber, the instrumentation system involves a light soiu-ce, photodetector and associated display, optical components such as lenses, couplers and connectors, and monochromators or filters for wavelength selection. A typical instrumentation system employed in conjunction with photometric sensors is shown schematically in Figure 3. 

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