Kerr Moke
Magneto-optical Kerr microscope & magnetometer
The macroscopic properties of a magnetic material (hysteresis, energy loss, magnetic noise, etc) are determined by its magnetic microstructure, i.e. by magnetic domains and their reaction to magnetic field excitation. Therefore domain observation is essential for the development of magnetic materials and understanding of magnetization processes.
The evico magnetics Kerr Microscope & Magnetometer systems are facilities for the visualisation of magnetic domains and magnetization processes as well as for optically recording magnetization curves on all kinds of magnetic materials, including bulk specimens like sheets or ribbons, magnetic films and multilayers, patterned films or micro- and nanowires. They are semi-automatic, contact-less, non-destructive measuring systems using the magneto-optical Kerr effect (MOKE) as contrast mechanism.
Two microscope systems, both based on Carl Zeiss optics, are offered:
- Standard Microscope, and
- Combined High-Resolution & Overview Microscope.
The Combined System is a more flexile setup that combines two microscope versions:
- a low-resolution version that allows to obtain an overview of the domain pattern of larger samples with a variable spot size ranging from approx. 30 x 30 mm to 8 x 8 mm
- a high-resolution optical microscope that allows for the same spot size- and resolution ranges as the Standard Microscope.
Both versions are implemented in the same setup and can be used optionally.
For all microscope systems, image processing capabilities are provided for contrast enhancement. Magnetic in-plane fields of arbitrary direction can be applied. Optionally, also out-of-plane magnets are available. Magnetization loops on selected spots of the sample surface can be optically measured (MOKE-magnetometry), observing and recording the corresponding domain images at the same time. The microscopes can readily be extended to high- and low temperature observations. Also, quantitative Kerr microscopy and stroboscopic (time-resolved) microscopy can be implemented.
The microscope systems have been developed by Prof. Dr. Rudolf Schäfer and Prof. Dr. Jeffrey McCord, who have long-lasting experience in the field. Prof. Dr. Schäfer is coauthor of Springer monography Magnetic Domains: The Analysis of Magnetic Microstructure.
Also, the philosophy of evico magnetics is unique: we offer Kerr microscopy, and not just the microscope system. We are glad to collaborate with our customers on a scientific basis, delivering ongoing help on domain interpretation and advice on optimizing the magneto-optical experiments.
Combined Microscope
The combined system is a highly flexile setup that combines two microscope versions:
- a low-resolution version and
- a high-resolution optical microscope.
Both versions are implemented in the same setup and can be used optionally.
High Pressure Milling Vial
A new and powerful method for the synthesis of hydrogen storage materials and monitoring of hydrogenation reactions by reactive ball milling under high hydrogen atmosphere has been developed. It involves high-energy ball milling in an especially designed vial, allowing in-situ monitoring of temperature and, more importantly, of hydrogen pressure by incorporating a newly developed gas-temperature measurement system as well as a radio emitter into the vial lid. An external receiver transmits the data to a data acquisition computer. (O. Gutfleisch et. al., J. Alloys and Comp. 427 (2007) 204)
- insight in physical and chemical processes during high-energy ball milling
- of functional materials such as hydrides, intermetallic compounds, ceramics, bulk metallic glasses etc.
- quick check of catalytic efficiency
- accelerated hydride formation and nanocrystallinity
Features:
- Continuous in-situ monitoring of pressure and temperature during ball milling
- pmax= 150 bar of hydrogen (smaller pressure ranges with higher resolution available: up to 1-2-5-10-20-50-100 bar)
- Operation time up to 40 h
- Resolution of data acquisition: 40 points/s
- Powerful dedicated software
- USB interface
- Volume of milling vial: 220 ml
- Vial material: hardened steel, swagelok ball valve
Options:
Two channel system for simultaneous use of two milling vials
Description
The Transmission DHM®-Series are designed for measuring transparent or semi-transparent samples. There are available in two configurations : DHM® T-1000 operating with a single laser, and DHM® T-2100 operating with two lasers.
In life sciences
DHM®-T provides precise Quantitative Phase Measurements (QPM) of living cell cultures up to confluence, without the use of any contrast agent and with very low illumination power. The DHM®-T is an ideal instruments for high content screening, time lapse measurements and diagnostic. Used in conjunction with the optional fluorescence module, it enables simultaneous DHM® and fluorescence measurements. It is compatible with motorized stages. and with a large choice of accessories for working with living cells.
In material sciences
DHM®-T measures specimen shape and surface, as well as material optical parameters, internal structure and defects. It is an ideal tool for characterization of micro optics, providing shape, refractive index and optical transfer function. Refractive index liquids can be used for characterization of steep slope samples like micro-corner cubes and Fresnel lenses among other. Other major applications are characterization of micro-fluidics devices and 3D- particle flow velocimetry. Systems are compatible with motorized stages, stroboscopic module and the post-analysis software for MEMS analysis.
4-Pole Magnet
- Computer controlled rotating magnetic field (manual control with hand-wheel on control panel is also possible) For in-plane magnetic field
- Superposition of DC and AC fields at different angles
- Supported on a magnet holder with adjustable height, independent from sample holder
- Water-cooled
Perpendicular Coil
- Generates magnetic field along the direction of the objective axis
- Field strength up to 100 mT
- Supported on magnet holder with adjustable height, independent from sample holder
- Water-cooled
Perpendicular Electromagnet
- Generates magnetic field perpendicular to the sample surface (i.e. along direction of objective axis)
- Field strength up to 950 mT
- Supported on magnet holder with adjustable height, independent from sample holder
- Water-cooled
Single Sheet Magnet
- Magnetization stage for domain observation in electrical steel sheets in Epstein geometry (30 x 300 mm, sheet thickness variable) and amorphous and nanocrystalline ribbons of usual geometry
- Flux closure by laminated yoke
- In-situ application of tensile stress up to 100 MPa
- Pickup coil for measurement of AC hysteresis loop
DOMMIS: Texture-Analysis tool
Special tool in the software, designed for the semi-automatic determination of the (main) orientation angles of individual grains in Goss-textured FeSi transformer steel by domain analysis.
Non-Magnetic Objective Lenses
Non-magnetic lenses with strongly reduced ferromagnetic components.
Sample position stabilization (piezo-stage based)
Kerr microscopy strongly relays on digital image processing and especially on difference-imaging technique, thus any tiny displacement of the sample due to time drift of in-field movement may lead to a drastic deterioration in imagining quality.
To overcome this, we have developed an advanced sample holder with integrated Pizeo Stage. Sample, been mounted on this holder can be moved in all XYZ directions by approximately 80 microns, and special software traces any feature at the sample surface (defect or structure element) and if any displacement is detected, it moves the whole sample holder back to initial position, thus making imagining with subtraction possible
- Movement rage 80 microns in XYZ directions
- Automatic position stabilization in XY plane
- Automatic and manual in-situ focus adjustment
- Compatibility with in-plane coils and out-of-plane electromagnets
An example of the application of the sample stabilization to domain observation in NiFe film element is shown below: The observed live image is disturbed by sample movement in XY plane and later the quality is restored by counteraction of the piezo stage.
Cryo-stage
- Temperature range: 4 K – 325 K
- Especially adapted for the needs of Kerr microscopy: the sample is fixed by thermally conductive glue on an elongated cooling finger
- Observation through a glass window
- Cryostat can be used together with evico magnetics rotatable (“standard”) magnet and perpendicular coil
- Sample size: < 9 mm circular diameter
- Stage table, xy-shift by approx. ± 5 mm
- Long distance objective lenses (20x – 50x, corrected for glass window)
- Additions: temperature measurement and regulation system, isolation vacuum pumping system, liquid gas transfer line, vibration-damped pump stand etc
Optical heating stage
- Temperature range: 300 K – 890 K
- Especially adapted for the needs of Kerr microscopy: the sample is mechanically fixed on an elongated heating finger Observation through a glass window<.
- Stage can be used together with evico magnetics rotatable (“standard”) magnet and perpendicular coil Sample size: < 9 mm circular diameter
- Stage table, xy-shift by approx. ± 5 mm
- Long distance objective lenses (20x – 50x, corrected for 1 mm glass)
- Additions: temperature measurement and regulation system, isolation vacuum pumping system, liquid gas transfer line, vibration-damped pump stand etc
