Plants metabolism changes as function of parasitic attacks, nutrients of the ground, environmental condition. This characteristic has been exploited to diagnose possible stresses, for a better control of the production processes to increase the perceived quality in agricultural products, to evaluate the environmental quality and to monitor the effects of human activities on the environment, using plants as the primary sensor. These aims have been pursued through the development of a knowledge based instrument for the early identification of a plant stress state, a hard task to be performed even by a human expert. It is known that information on the photosynthetic apparatus can be obtained from the analysis of the chlorophyll fluorescence. The chosen procedure, known as OJIP test, is based on measurements of the fluorescence dynamic behaviour at 730 nm as it is related with the chlorophyll. The stimulus is generated with an amplitude modulated laser diode, the fluorescence detection is done by means of a photomultiplier to reach a good sensibility. The proposed instrument integrates the knowledge of human experts and laboratory diagnostic techniques for an on-site, non-intrusive and remote analysis.
In ultrasonic phacoemulsification during cataract surgery the lens material fragmentation has been described as being caused by a combination of several mechanisms. The different theories involve tip vibration, acoustic waves produced by the tip, particles and liquids impact on the surface of the lens and cavitation. However the mechanisms are still not clear. To better understand phaco-related phenomena we have tried to produce a description in term of images of the cataract phacoemulsification procedure.
An expanded and collimated laser diode beam transilluminates a transparent tube containing a liquid medium. The machine is activated separating the different phases of irrigation, aspiration and phacosonication.
Fluid turbulences and phenomena related to the tip vibration constitute the phase images, visualized using Schlieren or similar techniques. The optical Fourier transform is filtered by a blade or by a black dot. The filtered transform is reconstructed into the visualized phase image and this is acquired by a digital image processing system. The presence of acoustic cavitation and possibly of ultrasonic radiation has been revealed.
The technique promises to be a possible means for evaluation of single phaco apparatus power setting and comparison between different machines in terms of power modulation and cavitation production.