| 摘要 |
A first heater is attached to a sensor capable of emitting thermal radiation toward an object to be sensed. Electrical energy provided to the heater, required to maintain the sensor at a predetermined temperature when it is radiating energy toward the object is monitored by a circuit which provides a signal that is indicative of the required energy. A second heater provides a baseline temperature for the sensor. For greater accuracy, two sensors are heated by a common baseline heater. One of the sensors is shielded from radiation toward the object and controls the baseline heater, the other sensor emits thermal radiation toward the object and has a heater for maintaining it at a predetermined temperature for providing the signal indicative of the required energy as described above.
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