| 摘要 |
PROBLEM TO BE SOLVED: To provide a smog transmittance measurement apparatus used for visual transmittance measurement within a road tunnel capable of solving a problem of conventional smog transmittance measurement apparatuses in which, since a light projection section and a light receiving section are generally disposed being separated 100 m from each other, after a system is installed, the electric signals are hardly corrected in a standard state of transmittance 100% resulting in some variations in calculation of the electric signals into the transmittance depending on the apparatus; while an optical fiber used causes a system to be expensive.SOLUTION: Transmittance correction timing and a standard transmittance are calculated based on time-base-changes of electric signals from the light receiving section 2 which collects electric signals at constant intervals. A high reliable calculation of the transmittance can be made without requiring additional correction device. |
