Ploughshare-type cutting bridges 4 may be age distribution network

摘要

A thermal imaging system which is ac coupled and operates by scanning recreates a thermal image by superimposing measured variations in infrared emission from a scene 22 on to a reference level supplied by a light emitting diode 28 . The diode 28 is both a positive and negative luminescent emitter; emitted flux is current controlled to be equivalent to black body radiation at a range of temperatures which may be colder or hotter than ambient. A signal generated when the system switches between scene and diode observation is a measure of the difference between the mean scene temperature and the diode effective temperature. In response to this signal, control means adjust the bias current through the diode 28 in order to reduce the temperature difference. The reference temperature converges towards the mean scene temperature as this process is repeated. Absolute temperature is thus restored and some image defects removed.