Magneto optics
Magneto-optics deals with visualisation of magnetic fields. Such investigations use magneto-optical sensors based on the Faraday effect. The sensor technology is applied for field analysis and quality assurance of different magnetic materials.
Magneto-optics at the MOS department comprises application-oriented growth and preparation of magneto-optical sensor films and the development of systems for visualisation of magnetic stray fields. For fabrication of magneto-optical sensors we use liquid phase epitaxy based on high quality single crystalline films.
Service
- Customised development of magneto-optical sensors and systems
- Magnetic stray field investigation of different magnetic materials
- Faraday rotation measurements
- Optical film thickness measurements via prism coupler
If you have any questions, please contact us.
Faraday effect
The magneto-optical effect describes the rotation of the polarisation plane of linear polarised light inside the sensor. The magnitude of Faraday rotation depends on the magnetic field strength of the test sample. The field parallel to the propagation direction of light is sensory detected. You get an optical image, which illustrates a 2-dimensional cut through the magnetic stray field of the test sample.
Configuration
For visualisation the magneto-optical sensor works in reflexion mode in direct contact to the magnetic sample surface. The formed image contrast depends on the local strength and direction of the magnetic field. The sensor transforms one field direction to a bright intensity and reversely to a dark intensity.
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Sensor material
The best material for magneto-optical imaging is bismuth substituted rare earth (RE) iron garnet (stoichiometry (Bi,RE)3(Fe,Ga)5O12). Garnet layers are grown by liquid phase epitaxy on 1 inch and 3 inch gadolinium gallium garnet substrates (Gd3Ga5O12).
Characteristics
Typical properties of our magneto-optical sensors:
| specific Faraday rotation | 1.3 °/µm | working temperature |
25 °C |
| magnetic range |
0.01 to 160 kA/m |
sensor size | Ø ≤ 70 mm |
| resolution | 1 to 20 µm | sensor thickness | 0.5 mm |
| transmission range (VIS) | λ > 530 nm |
Sensor design
For optimised application conditions magneto-optical sensors will be coated by customised mirrors and scratch resistance layers optionally.
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Handheld device for fast checking of magnets, magnetic stripe cards, magnetic encoders and banknotes |
Direct magneto-optical imaging of magnetic materials: One-shot field mapping and stray field analysis of magnets, cards, encoders and banknotes using camera technique and software applications |
Forensic investigations of different audio tapes by a camera-based system (acquisition and analysis) |
contact: Mr. M. Lindner phone: ++49 (0)3641 282541