| 摘要 |
PURPOSE:To measure visual transmittance with good accuracy despite fluctuation in the coefft. of wavelength by using the spectral transmittance of two wavelengths only for 100% calibration of the visual transmittance in measuring the smoke conc. in a tunnel. CONSTITUTION:This is a method of making calibration of transmittance 100% after the optical axes of a light projecting part and a photodetecting part are set in a tunnel, wherein the zero correction value (e) of optical densities is calculated by the equation I from the total four signal outputs; the signal outputs S11, S12 for the optical densities of the wavelengths lambda1, lambda2 measured at smoke concn. C1, and the signal outputs S21, S22 corresponding to the optical densities of the wavelengths lambda1, lambda2 measured at smoke concn. C2, and the gain of an amplifier is adjusted according to the zero correction value (e) in the control part of a smoke transmittance measuring device. |
