Illumination systems Image analysis methods

The image analysis of UV photomicrographs is carried out by means of a microdensitometer using an X-Y scanning stage or a TV camera. However, the absorbance value obtained may be influenced by the methods of film development or by unevenness of illumination. It is difficult to eliminate the latter completely from the optical system of a UV microscope. 

The feasibility of employing fluorescent tracers and video imaging analysis to quantify dermal exposure to pesticide applicators has been demonstrated under realistic field conditions. Six workers loaded a tracer with the organophosphate pesticide, diazinon, into air blast sprayers, and conducted normal dormant spraying in pear orchards. They were examined prior to and immediately after the application. UV-A illumination produced fluorescence on the skin surface, and the pattern of exposure was digitized with a video imaging system. Quantifiable levels of tracer were detected beneath cotton coveralls on five workers. The distribution of exposure over the body surface varied widely due to differences in protective clothing use, work practices and environmental conditions. This assessment method produced exposure values at variance with those calculated by the traditional patch technique. 

The basic idea of this method is the analysis of particles settling under gravity using a digital image acquisition system. A continuously operating CCD camera, with a frame grabber, tracks individual particles illuminated... 

Summarizing this section, we developed the time- and spectrally-resolved fluorescence imaging system based on line illumination, which is capable of rapid acquisition of fluorescence intensities as a function of Em, x, and %y-positions. We applied this method to the analysis of a plant defense response, accumulation of antimicrobial compounds of phytoalexin in oat leaves, induced by the elicitor. In addition to the strong fluorescence from chlorophyll molecules, weakly fluorescent components, one of which possibly originated from avenanthramide A as phytoalexin, were observed in oat leaves treated with an elicitor. 

Visualization, documentation, and analysis of the results are very important aspects of each experiment. Commercially available gel documentation systems are equipped with various types of detection methods and software. Depending on the type of dye, several devices can be used, such as scanners, CCD cameras, illuminators with UV or white light, fluorescent imagers, and laser densitometers. For each image system, there is compatible software for processing and evaluation of the results and for data documentation. 

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