| 摘要 |
PROBLEM TO BE SOLVED: To provide a smog transmittance measurement apparatus used for transmittance measurement within a road tunnel capable of solving a problem of conventional apparatuses that, a long optical fiber cable of approx. 100 m has to be laid between a light projection section and a light receiving section for performing calibration causing a high work cost.SOLUTION: A calibration light receiving element 14 is provided within a light projection section 1 to detect the light which is emitted from a light source 3 and passes through a light projection lens 4 with a calibration light receiving element 14 via an optical fiber cable 10a to thereby calibrate the light projection section 1. Further, a calibration light source 15 is provided within a light receiving section 2 to detect the light which is emitted from a calibration light source 15 and passes through a light receiving lens 6 via an optical fiber cable 10b with a calibrate element 5 to thereby calibrate the light receiving section 2. Thus, the smog transmittance measurement apparatus can be calibrated with inexpensive means. |
