| 摘要 |
PURPOSE:To make a highly accurate calibration near a real measuirng condition possible by a small quantity of calibration gas, by enclosing zero gas and the calibration gas in two pairs of cells and obtaining a signal for span calibration by varing the quantity of light from a light source at a constant period. CONSTITUTION:Zero gas and measurement gas are introduced into cells 2a and 2b alternately at a constant period in accordance with switching and a cross flow system gas analysis is carried out. After a voltage damping modulation part 7 is incorporated in an electric power source circuit for light sources 1a, 1b, a signal in accordance with the unbalance of the sources 1a, 1b or both chambers 3 of a detector is given by enclosing the zero gas in the cells 2a, 2b and operating the part 7 and then, switching a quantity of light of the sources 1a, 1b at the same period as the constant period of measuring time. Next, calibration gas is enclosed in either of the cells 2a, 2b and a signal corresponding to the concentration of the calibration gas is given and then, a span calibration signal under nearly the same condition wth the real measurement is obtained by correcting this signal by the signal in accordance with the unbalance. Accordingly, a highly accurate calibration near the condition of the real measurement is performed by a small quantity of the calibration gas. |
