| 摘要 |
PURPOSE:To know which sensor operates by putting an optical fiber which cuts off light with specific wavelength in and out of between rod lenses of a light collimation system consisting of two optical fibers and two rod lenses. CONSTITUTION:Light emitted by an optical fiber 21a is converted by a rod lens 22a into a parallel light beam 26, which is passed through a hole 27 bored in a movable member 23 and converted by a rod lens 22b, so that the light is incident on a fiber 21b. When outside air temperature rises, a spiral bimetal 24 contracts, for example, so the optical fiber 28 which cuts off light with wavelength lambda is lowered to cover the hole 27. Consequently, the light 26 with the wavelength lambda is cut off and only light with other wavelengths is transmitted through the filter 28 and incident on the fiber 21b. For the purpose, a multiplexer is connected to the optical fiber (b) to demultiplex the incident light 26 by specific wavelengths and then the light with the wavelength lambda is not detected. Therefore, no light is detected, so it is known that a sensor having the filter 28 which cuts off the wavelength lambda is in operation.
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