| 摘要 |
PURPOSE:To cover a wide range area by a single detection unit by a method wherein measurement optical routes passing through detection points are sequentially changed over according to different combinations and position of pollution gas generation is read at detection points of a specific number or less in accordance with the combination of detection outputs. CONSTITUTION:Laiser light from a laser source 30 to measurement optical routes A, B, C are changed over by a selective insert and outset to and from optical axes of two optical route switching movable mirrors MS1 ans MS2. With this, on seven gas tanks 2-8 which are detection points, it is shaped that an n mesurement optical routes, for exmaple, three different measurement optical routes A, B, C are set in a mutually different combination. When an yes or no for existence of each optical route passing on each tank is indicated in a binary code, each tank can be indicated by each peculiar binary code. As a result, when the detection output of laser light from the laser source 30 introduced sequentially to the optical routes A, B, C is interpreted by means of a detection unit 20, a gas tank which is the generating source of pollution gas can be specified from among 2<n>-1 pieces of gas tanks. |
