| 摘要 |
PURPOSE:To detect quantitatively and with high accuracy the irradiance extending over a wide wavelength range, by intermitting an input radiation to a pyroelectric type radiation detecting element, by an optical shutter, and thereafter, converting it to a DC output. CONSTITUTION:A photodetecting angle sensitivity characteristic of a photodetector is made approximate to a cosine rule by a transmission diffusion structure 2. A diffused light beam from the transmission diffusion structure 2 is intermitted by an iris shutter 3, and placed in the vicinity of the photodetecting surface of a pyroelectric type radiation detecting element 1. A concentrical opening and closing center of this iris shutter 3 is made to a coincide with the center of the transmission diffusion structure 2 and the center of the photodetecting surface of the pyroelectric type radiation detecting element 1, by which even if the opening of the iris shutter 3 is in any state hourly, the photodetecting angle sensitivity characteristic of the photodetector is made approximate to a cosine angle. Accordingly, it does not occur that the photodetecting angle sensitivity characteristic of the photodetector is varied hourly by opening and closing of the iris shutter 3, and its cosine rule approximation is not deteriorated. |
