| 摘要 |
PURPOSE:To improve detection accuracy by preventing malfunction due to diffused reflection by greatly reducing a difference in radiant energy caused by a difference in temperature by obtaining a difference in output between two different infrared band-pass filters where a detected body is passed through. CONSTITUTION:Radiant light 2 from a detected body is separated by semitransparent mirror 13 into two, which strike the photo detection surfaces of photoelectric converters 6a and 6b by way of two infrared band-pass filters 12a and 12b differing in center wavelength (e.g. 4.3mum and 2.5mum). Output voltages from both converters 6a and 6b are inputted to differential amplifier 14 to obtain a difference between the both. As a result, an output-voltage ratio between photoelectric converters at the highest and lowest temperatures can be reduced down to a single- digit numeral and even if a reflector of zero to approximate tens % in reflection coefficient would interpose, no detection error appears. |
