| 摘要 |
PURPOSE:To improve measurement accuracy by using lenses and prisms. CONSTITUTION:A lamp 1, condenser lens 5, the 2nd prism 9, lens group 6, glass plate 8 which delineates the smoke density measuring section A, the 1st prism 7, and the 1st, the 2nd photo detectors 11, 12 are arrayed in a cylindrical barrel 10. As a result of this, part of the light from the lamp 1 is reflected by the 2nd prism 9 and is received in the 1st photo detector 11. The rest is parallelized by the lens group 6 and passes through the smoke density measuring section A. This light is reflected by the 1st prism 7 and again passes through the smoke density measuring section A and is received in the 2nd photo detector 12 via the lens group 6 and the 2nd prism 9. Since the 1st and the 2nd photo detectors 11, 12 are thermally coupled and have the same characteristic, the smoke density which is compensated with respect to temperature characteristics is measured from the ratio of both the photo detecting outputs. |
