To obtain an accurate non-contact temperature-measuring sensor by arranging an optical filter with characteristic for cutting the long-wavelength side for the fundamental wavelength of a diffraction optical lens on an optical axis.
A diffraction optical lens 3 for condensing infrared rays is provided inside an enclosure 1 on the optical axis of an infrared light reception part 2. Also, a filter 5 for cutting a long-wavelength side for the fundamental wavelength of the optical lens 3 is arranged at incidence light-limiting window 4 on the optical axis of infrared rays at the other end of the enclosure 1. Infrared rays emitted from an object to be measured pass through the filter 5, are condensed by the optical lens 3, and enter the infrared light reception part 2. In this manner, the long-wavelength side is relaxed by the filter 5 for cutting the long-wavelength side. Further, by relaxing the short-wavelength side with the incidence light-limiting window, a visual field is narrowed, thus using an inexpensive diffraction-type lens and at the same tiem acquiring a small visual field angle and improving measurement accuracy.
FUJIKAWA KAZUHIKO
NOMURA KOJI
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