| 摘要 |
PURPOSE:To provide the subject method comprising the steps of imparting a step- wise variation to a current supplied to a wavelength variable laser, and seeking a derived function of a photo power on the basis of the variation of the photo power corresponding to the difference in the current, whereby the construction of an atmospheric contamination measuring system is economized and simplified. CONSTITUTION:The waveform of a laser current is stepwisely modulated by a current programming circuit 11 the vibration number of luminance of a waveform variable type semiconductor laser 1 varies similarly. Modulatd light rays are collected in an infrared ray detector 7 via a lens 2, chopper 8, a concave mirror 3, atmosphere containing noxious gases, a bent reflection mirror 5, atmosphere 4, a Cassegrain mirror 6, and holes of concave mirrors 6a. The output signal of the detector 7 is treated in a signal treating circuit 13 via a preamplifier 12, and the derived function Pr' of the power Pr of modulated light is sought and Pr'/Pr is sought in a division circuit 14. On the other hand, light rays passing through a light ray branching device 9 is similarly treated, and P'/P0 normalized by the output light power P0 is sought, a value proportional to the concentration of a noxious gas obtained by a differential circuit 18 is recorded by a recorder 19. |
