| 摘要 |
PURPOSE:To achieve a higher accuracy of measuring and detecting infrared rays, by providing a plurality of filters in a light receiving optical path to remove a disturbed light with an undesired wavelength significantly. CONSTITUTION:A detector 2 is made up of a base 21 and a cap 22 and has an infrared sensor 20 inside. A transmission window section on the top of a cap 22 is provided with two filters 4 of roughly the same characteristic comprising a band pass filter or the like and an output of the element 20 is taken out of a lead pin 23 of the base 21. In this manner, the filter 4 has a transmissivity of 0.7X0.7=0.49 above 6mum enough for measurement and that of 0.001X0.001=0.000001 below 6mum and a disturbing light L is mostly attenuated. This removes a disturbing light with an undesired wavelength such as sunlight significantly, thereby achieving a higher accuracy of measuring and detecting infrared rays. |
