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:
The Combined System is a more flexile setup that combines two microscope versions:
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.
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)
Two channel system for simultaneous use of two milling vials
|Objective||Single, fixed||Multiple on a turret||Multiple on a turret|
|Configuration||One laser source||One laser source||Two laser sources|
|Measurement modes||Single wavelength||Single wavelength||Single and dual wavelength|
|Accuracy (as demonstrated by taking the temporal standard deviation on 1 pixel over 30 measurements)||1.0 nm 1||1.0 nm 1||1.0 / 5.0 nm 1 *|
|Vertical resolution (defined as twice the accuracy)||2.0 nm 1||2.0 nm 1||2.0 / 10.0 nm 1 *|
|Repeatability (as demonstrated by taking the one sigma Rq value of 30 repeatability measurements on SiC reference mirror)||0.02 nm 1||0.02 nm 1||0.02 / 0.05 nm 1 *|
|Vertical measuring range (without any scanning)||
|Max. height of steps with sharp edges (Depends on the laser source(s) and operating wavelength(s)||
1) Converted value for measurements in air and with sample refractive index n=1.5
2) Converted value for measurements in water and with sample refractive index n=1.5 * With / Without single wavelength mapping
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.
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.
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.
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
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.