IMAGEUR THERMIQUE

• Main Authors: C.A. BERRY, I.H. HOWIE, P.J. BERRY
• Format: Patent
• Language: French
• Published: 16.09.1981
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; PICTORIAL COMMUNICATION, e.g. TELEVISION

A thermal imager comprises a scanner (13), detector (14) with mount (14A) cooled substantially below ambient temperature, and which via a reflector (16) on the locus (15) along which an image of the detector (14) is effectively scanned provides a characteristic radiation feature to the detector (14) in superimposition with the scanned radiation from the scanner (13). The scanner (13) operates with less than 50% efficiency so that in the detector output signal the scene-derived waveform has a duration T1<50%T, where T is the period of the detector output signal. The characteristic radiation feature gives rise to a sync signal at the detector output and is located prior to and closely adjacent the scene-derived waveform at a time interval T2 prior to the end thereof. This sync signal is detected by a recognition circuit (20) and activates a monostable forming part of a clock circuit (22) for a duration T3 such that T2<T3<50%T. The clock circuit (22) controls the timing of signal processing circuitry (24) and a video output device (25) connected to the output of the detector (14).