| 摘要 |
<p>PURPOSE:To perform a stable measurement in which the influence of a noise is comparatively small by a method wherein visual-field ranges viewing the inside of a measuring cell via opening parts in an optical shielding plate from infrared detection elements for measurement and for compensation are made nearly equal. CONSTITUTION:Optical-shielding plates 19 which are provided with rotation central axes 12 and whose positions can be adjusted are arranged respectively with reference to two sets of detection elements #1, #2. When the position of the shielding plates 19 is adjusted, the shielding plates 19 are provided with opening part which are opened at equal intervals on both sides from an action line passing through the center of a photodetection face 11 in an infrared sensor 6. The shielding plates 19 are turned from parts in which they have been adjusted fully to the right, the incident light quantity on the sensor 6 can be adjusted fine so as to be nearly proportional to their rotation angle. By this constitution, since the central line of the opening parts coincides with the center of the photodetection face 11, visual-field ranges viewing the inside of a measuring cell 1 from the photodetection face are symmetric with respect to a perpendicular line from the center of the photodetection face 11. Consequently, while visual fields for both detection elements are kept identical, an optical adjustment can be performed.</p> |
