Principle
Faraday effect in reflection
The Faraday effect describes the rotation of the polarization plane of linearly polarized light within the magneto-optical sensor film. The Faraday rotation inside the sensor is caused by the magnetic field of the sample. Magneto-optical sensor primarily detects magnetic field components parallel to the direction of the light propagation.
Sensor technology
Magneto-optical sensors operate in reflection mode in direct contact (near field) to the magnetic surface of the sample. The resulting optical contrast is influenced by the local strength and direction (polarity) of the magnetic field. The result is an optical image that represents a two-dimensional slice through the magnetic stray field of the sample. Using camera-based sensor technology (CMOS-MagView), magneto-optical images can be recorded under defined conditions as high-resolution grayscale images. This enables industrial image processing.
Image generation and profile extraction
A magnetic linear encoder has a sinusoidal-alternating field polarity in the direction of motion. If the magnetic surface of the encoder is positioned on the sensor area, the magneto-optical image is directly generated. The image data qualitatively corresponds to the local stray field distribution.
A calibrated CMOS-MagView makes it possible to quantitatively convert the obtained grayscale image into magnetic field values. Thus, a field image is generated from the magneto-optical image pixel-by-pixel. This field image now represents the magnetic field strength distribution. Image evaluation allows various analyses, such as amplitudes and pole pitches of field profiles, e.g. in the direction of motion of the encoder.
The magnetic field distribution of the sample can be analyzed within a few seconds.
