Thermal imaging systems

Hofmeister et al. 4l() employed two high-speed thermal imaging systems to record spatial and temporal temperature distributions at the splat-substrate interface, and to observe droplet spreading during impact and solidification on a quartz plate. They observed... 

There are many excellent differential scanning calorimeter systems available which can be used to measure the specific heat which, when combined with the sample density can be used to give c . The thermal diffusivity (which can be important for thermal imaging systems if the target is not reticulated) can be measured directly on a pyroelectric substrate using the laser intensity modulation method described by Lang [23],... 

M. K. Chyu and D. J. Bizzak, Surface Temperature Measurement Using a Laser-Induced Fluorescence Thermal Imaging System, ASMEJ. of Heat Transfer, 116, pp. 263-266,1994. 

A. P. O Leary in Electro-Optics, Special Report on Thermal Imaging Systems, 2nd edn, Jane s Information Group, Antony Rowe Ltd, Chippenham, Wiltshire, UK, 1994. 

To date there has been little or no success in commercializing monomolecular assemblies of this type. However, certain areas of investigation have exhibited promising results, which have prompted investment in applied research and development. These are described in this paper. They have been grouped into three sections. The first two deal with passive and active applications of LB films. The final section concentrates on the strong claims for pyroelectric LB films to be used in thermal imaging systems. 

Experimental techniques are discussed for the characterisation of potentially useful thin film materials, including measurement of pyroelectric coefficient and dielectric data (permittivity and dielectric loss). It is noted that, when considering a complete thermal imaging system, it is not sufficient to consider material parameters in isolation, and that the combined features of LB films render them particularly suitable to high system performance. 

The most promising thermal imaging system is that using the pyroelectric vidicon. The present development stems from the work of Hadni et al. [3.74,75]. 

The ultimate in thermal imaging systems will no doubt be some completely solid state system Barbe [3.80]). It is not clear whether pyroelectric Steckl et al. [3.81]) or other thermal sensors can be employed in this, but the possibility has the attraction of appearing to be the only one which does not require any cooling below normal ambient temperatures. 

Series/Parallel Scan with time delay and integration remains the principal approach to advanced thermal imaging systems. However, for applications where only a small number of resolution elements are needed, two-dimensional staring detector arrays with CCD or CID readout are being considered [8.106]. This does away with the scanner and a focal optics used with conventional systems. However, to compensate for nonuniformities, both dc offset and gain correction must be made on a pixel by pixel basis. Detector responsivity and readout nonlinearities will increase the number of computations needed for sufficient correction and only experience with the stability of different types of arrays will determine how often the correction algorithms must be calibrated [8.107,108]. 

Thermal-imaging systems are now being marketed for night driving, heavy equipment operators, maritime applications, and pilots. As the costs of these systems decline they will be more widely available for the general public and possibly may eventually become a standard option in passenger vehicles. 

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