MESSWANDLER AUF DER BASIS DES ELEKTRO- BZW. MAGNETOOPTISCHEN EFFEKTES

1. Measuring transducer based on the electro-optical or magneto-optical effect, comprising a detector constituted by an optical fibre coil having a large electro-optical or magneto-optical constant as a modulator (2) and a succeeding analyser (3) for detecting a rotation of the plane of polarisation, characterized in that - the analyser (3) is designed to respond only to one or several certain predetermined angular positions of the plane of polarisation of the light and moreover detects the direction of passage of the plane of polarisation, - the optical fibre coil is formed of an optical fibre (5) of sufficient length for the influencing electrical or magnetic field to cause such a large rotation of the plane of polarisation that the analyser (3) responds several times to the value which is to be measured, and - counting means is provided which is comprised of a logic circuit (41, 42) for detecting the analyser pulses and for discriminating a forward or reverse rotation of the plane of polarisation, and of a digital up-down counter (43) to the parallel outputs of which the measured value is applied in digital form.