| 摘要 |
<p>A measuring instrument 1 for determining the percentage of a component in a fluid that is less affected by changes to the test radiation due to drift or thermal conditions. The instrument comprises a measuring chamber 2 having a first surface 3 housing an infrared radiation source 4 and a detector 5, on a second surface 6 are arranged two or more reflectors 71,72. The test beams 10,11 emitted by the radiation source 4 are reflected onto the receiving surface 12 and the area of each reflector 71,72 is designed so that its illuminated area near the detector 5 is greater than the receiving surface 12 of the detector 5. The instrument may comprise a reference detector (16,Fig2) having a receiving area (17,Fig2) whereby one reflector 71 is aligned with detector 5 and the other reflector 72 is aligned on the reference detector (16,Fig2) such that the illuminated area near the reference detector (16,Fig2) is greater than the reference receiving surface (17,Fig2).</p> |
