| 摘要 |
Induced fluorescence of air molecules is used to determine air data parameters such as barometric altitude. The air molecules at a sample location are caused to fluoresce by means of a suitable energy source. A detector having an effective field of view including the sample location measures the fluorescence emitted by the air molecules in the detection sample (the portion of the fluorescing region viewed by the detector). By the use of appropriate filters and/or appropriate selection of the energy source, it is possible to measure fluorescence only from a particular type of air molecule. Since the measured intensity is proportional to the number of excited air molecules, it is possible to compute the density of the air, the static pressure of the air, the partial density and pressure of any individual molecular species, and/or the barometric altitude. Accordingly, many critical air data parameters may be measured by means of equipment contained wholly within the skin of an aircraft, without requiring any pressure ports communicating with the external environment. If the fluorescing energy is switched on and off, an exponential decay of the fluorescence occurs, with mean fluorescence lifetime varying with the density of the fluorescing molecules. It is thus possible to utilize differences in intensity rather than absolute intensity measurements to determine the parameters of interest. |
