| 摘要 |
<p>PURPOSE:To reduce power consumption and to improve the possibility of the use of the title sensor in a place where explosion-proof effect is received and durability in corrosive atmosphere by supplying a measuring voltage to a liquid crystal filter and obtaining the attenuation factor of light. CONSTITUTION:Fixed light from a reference light source 1 is divided into two systems by a flow divider 2, one of which is conducted to a 1st photoelectric converter 7 through a 1st optical fiber 4, the liquid crystal filter 4 and a 2nd optical fiber 6 and the other of which is conducted to a 2nd photoelectric converter 9 through a 3rd optical fiber 8 so as to compare outputs in a comparator 10. The light transmitted quantity in the liquid crystal filter 5 is varied corresponding to the supplied voltage. On the other hand, the attenuation quantity of one of divided light which passes through the 1st and the 2nd optical fibers 5 and 6 is set to be equal to that of the other light which passes through the 3rd optical fiber 8. Thus, the output from the compartor 10 is changed corresponding to the voltage supplied to the liquid crystal filter 5 and the value of the voltage supplied to the liquid crystal filter 5, that is, measuring quantity, can be detected from the compared output.</p> |
