| 摘要 |
PURPOSE:To attain the simplification of adjustment and the enhancement of the accuracy of a VI value, by attaching a filler, which has an attenuation ratio such that the light receiving quantity of a light receiving part becomes same to the quantity of light received at a position separated by 100m in the atmosphere with a smog transmissivity value of 100%, to a correction stand. CONSTITUTION:In a main correction apparatus provided with a filter 3 having an attenuation ratio such that light receiving quantity at the time, when a light projection part 1 is separated by 100m from a light receiving part 2 in such a state that the transmissivity of air in a tunnel is 100%, becomes same to that of the light receiving part 2 at the time of adjustment, the light projecting part 1 and the light receiving part 2 in the tunnel are mounted to a correction stand 4 and a current is supplied to the lamp/motor power source of the light projecting part 1 and the power source of the light receiving part 2 from a light projecting side power source box 5 by prepared cables 8, 9 arranged to the side of the light projecting part 1 and the signal of the light receiving part having the same value as that, obtained when the transmissivity of air in the tunnel is 100%, is transmitted to a VI processing part 7 through the power source box 6 in the side of the light receiving part and 100% matching of a VI value is performed by the VI processing part 7. Next, the light projecting part 1 and the light receiving part 2 are returned to the initial mount positions and the cables are also returned to the initial positions to complete the adjustment of 100% matching and the accurate VI value can be measured. |
