| 摘要 |
PURPOSE:To offset background radiation against a dark current of a detector itself and a fluctuation thereof and thereby to take out only an object of measurement, by guiding the radiation from the object of measurement inclusive of the background radiation and this background radiation onto the detector, and by taking the difference between them. CONSTITUTION:The radiation from a visual field is inputted by a telescope 1 of a radiometer, while background radiation is inputted from a black body furnace 2, and incident beams from the black body furnace 2 and the telescope 1 are switched by a mirror chopper 3 according to a drive signal from a photocoupler 4. These input beams are made to enter a cooling means formed of a cooling filter 6 and a cooling baffle 7 connected to an infrared ray detector 8 in a Dewar flask 5. The detector 8 is cooled down by this cooling means, so as to reduce background radiation. An output signal from this detector 8 is processed by an input diode 11, an input gate 12, a storage well 13, transfer gates 14, 14', a channel stop 15 and CCD channels 16, 16' of a CCD device, and an output is delivered from a differential amplifier 17 after the backgrouds radiation is offset thereby against a dark current of the detector 8 and a fluctuation thereof.
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