| 摘要 |
PURPOSE:To simplify a condensing optical system, by executing functions of each light emitting element and photodetecting element by one semiconductor laser. CONSTITUTION:A measuring light passage passing through the space of a gas G to be measured between a semiconductor laser D and reflection means M1-M3, is established. Radiate beams of light having different wavelength each other are radiated from the laser D with different timing in progress of time by connecting electron switches Q1-Q3 which supply selectively driving electric current having different value each other to the laser D and operating the switches Q1-Q3. Hereafter, the driving electric current of the laser D is turned off and the laser D is made into a photodetecting element. Then, reflecting beams of light by means of M1-M3 are photodetected and the concentration of the gas in the space of the gas to be measured is known from a photodetecting output corresponding to the radiated light having different wavelength each other. A p-n junction in the semiconductor laser is utilized as a PV type photodetector, that is, the photodetecting element and luminous and photodetecting elements are excuted by one semiconductor laser. |
