| 摘要 |
PCT No. PCT/CH78/00023 Sec. 371 Date May 23, 1979 Sec. 102(e) Date May 23, 1979 PCT Filed Oct. 2, 1978 PCT Pub. No. WO79/00180 PCT Pub. Date Apr. 19, 1979 In the measuring and control technics, indicators for a limit value and measurement value working for example on an optoelectronic basis are used to determine magnitudes of physical and chemical nature. For solving such problems, particularly in fields where there are risks of explosion, a reference light beam (20 to 23) is used in parallel to the measuring light beam (13,15 to 17) representing the magnitude measured. A difference signal (36) is obtained resulting from both light beams and representing the magnitude of the information. With this signal, indicators of universal use for limit value and measurement value can be built, working in a precise and reliable way, even in severe operating conditions, by using preferably light guides (15,17,21 to 23). With the use of flexible light guides (15,17,21 to 23) and of separate light transmitters (13,20) of different frequencies (f1,f2), and with an alternate operation of said light transmitters, etc., a wide field of application opens that will subsequently link to information processing. |
