Faseroptischer Transmissionssensor mit Modulator

摘要

Fibre-optic sensors are used in reflection or transmission mode in almost all fields of measuring technology, among others, for monitoring industrial plants, in medical diagnostics and in aerospace. In these applications, the effects of mechanical, electrical, magnetic, acoustic, thermal and chemical signals are analysed. To provide for simpler signal analysis, laser light is coupled from a light source (1) into an optical feed line fibre (2) parallel to one of its two major axes. In a first splice (3), the light is introduced into a first optical reference fibre (4), the major axes of which are rotated by 45 DEG compared with those of the optical feed line fibre (2). In a second splice (5), the light passes into a second optical reference fibre (6) which has the same length as the first optical reference fibre (4) and which is rotated by 90 DEG with its major axes with respect to the first optical reference fibre (4). At a third splice (7), the light is coupled into an optical fibre (8) with low birefringence, which first forms a lambda /4 optical fibre loop (9) and then an optical sensor (10). The phase shift of the light can be statically or dynamically influenced by means of a phase modulator (M) in conjunction with the first optical reference fibre (4).