| 摘要 |
<p>PURPOSE: To continuously detect desired arbitrary two or three gas components by forming the concentration signal corresponding to the thickness of a fixed birefringent plate and a concentration signal corresponding to the sum of or difference between the thicknesses of the different birefringent plates at the planned instantaneous angular positions of the different birefringent plates. CONSTITUTION: The light from a light source 27 is made incident on a fixed birefringent planar plate 12 through a condenser 28, a lens 29, a measuring path 30, and a polarizer 11. The parallel plate 12 has a thickness d1 selected in the manner suitable for a gas component to be measured and birefringent planar parallel plates 14 and 20 respectively having thicknesses of d2 and 3 are arranged on the optical axis 15 of the plate 12. When, for example, the optical axis d2 of the plate 14 is positioned at an angle of 45 deg. against the direction of polarization during the rotational movement of the plate 14, the thicknesses d1 and d2 of the plates 12 and 14 are added and it is regarded that a single plate having the thickness corresponding to the sum of the thicknesses exists. When a lock-in amplifier 24 is actuated by means of an amplifier 34 in this state, a concentration signal C1 representing the gas component corresponding to the output of the amplifier 24 appears.</p> |
