Obiettivo The aim of the project is the development of an IR LIDAR system able to detect small methane concentrations. The system is based on a correlation technique and utilizes as laser source an optical parametric oscillator pumped by a NV-YAG laser. The system is designed to be a small, compact and reliable device suitable to perform measurement in an urban environment from movable platform, such as small lorries, using topographic targets as retroreflectors. Sensitivity goal is a minimum detectable concentration of about 50 ppm*m, which corresponds to the natural background concentration integrated over a double pass path of about 30 metres, i. e. at working distance from topographic target of 15 metres. The system has been designed to operate on ranges from 5 to 20 metres.In case of successful results, it will be sought a cooperation with an electronic firm, which already operates in the laser field.Field tests have been carried out during routine leak detection activity in the city of Milan and also on simulated leaks for comparison with conventional instrumentation.Sensitivity has been measured of the order of 150 ppm* m, corresponding to a uniform concentration of 5 ppm distributed on a double pass path of 30 metre (i. e. at a distance from topographic target of 15 metre).To improve this performance up to the needed one it will be necessary a review of the detector preamplifier design in order to reduce noise and a further optimization of the receiving optics.Field experience has shouwn the importance of a careful design of the moveable laboratory on the truck to make easier the use of the system in the urban environment, with problems arising from car traffic and parking.Further development is necessary to obtain a fully operative system.The detection method is based on the measurement of the atmospheric absorption of a laser beam by the gas to be detected; this technique is called Differential Absorption LIDAR (DIAL) and is used because it allows to cancel systematic errors due to target reflectivity and atmospheric scattering.Conventional DIAL techniques may lead to important errors when used to make measurements on moving platforms, since two laser shots are required; infact, time varying parameters, such as topographical target reflectance, may noticeably change during the time elapsed between the two shots, since the pulse rate is typically not grater than 10 Hz.The gas correlation method makes it possible to self-normalize the return signal obtained from a single laser pulse, thus leaving any time dependent environmental effect. Main disadvantages are a lower sensitivity and a greater effect of the measurement of interfering molecules. Programma(i) ENG-HYDROCARB 1C - Programme (EEC) of Community projects in the hydrocarbons sector, 1973-1985 Argomento(i) 1.6 - MISCELLANEOUS Invito a presentare proposte Data not available Meccanismo di finanziamento DEM - Demonstration contracts Coordinatore Azienda Energetica Municipale di Milano Contributo UE Nessun dato Indirizzo Corso di Porta Vittoria 4 20122 Milano Italia Mostra sulla mappa Costo totale Nessun dato
