Reuben Hale, P.E.
Ph: (510) 507-1300
Magnetic Field Sensitivity Testing - Sensitivity to stray magnetic fields is important for tools the using ion beams for process and inspection. We have instrumentation to measure AC and DC fields from nano-Gauss levels to hundreds of Tesla. We design the right custom coils, amplifiers and geometries for the testing space and application. We enjoy discussing magnetic field applications and have the equipment and expertise to perform testing quickly and produce meaningful results. See our discussion on Magnetic Field Testing.
We have been working with magnetic field issues for sensitive tools for many decades from cutting edge development of scanning electron microscopes to active cancellation systems for MRI tools, to site surveys for specification compliance, debugging, and tool magnetic sensitivity testing.
We have worked for many years on the development of new scanning electron microscopes (SEMs). A SEM image disturbance will often be caused by a combination of environmental vibration, acoustic noise, and stray magnetic fields, as well as on board sources, such as fan noise, fan imbalance, stage transients, stage control related disturbances (servo instability) and field from stray grounding currents.
These mechanical disturbances are filtered by the structural dynamics of the system and combine with magnetically induced disturbances of the electron beam and result in very confounding image problems.
We have made the task of untangling these issues our work for many decades. Our extensive structural dynamics and acoustics experience is indispensable to our ability to sort out cause and effect from these very different disturbance source types. A very firm grasp of basic physics allow us a broad range of problem solving ability on real systems (see Diagnostic Testing for more details).
We provide site analysis to insure that magnetically sensitive tools will perform well prior to installation. We typically look at floor and pedestal vibration, acoustics noise, and magnetic fields when performing a site survey for a SEM, or electron beam based tool (see Site Evaluation for more details).
In the last 10 years MRI installations have become more common place and we have performed numerous site surveys for these sensitive imaging tools. In some instances we have created custom active cancellation systems to correct a magnetic field problem that could not be resolved by other means. Many spaces where a SEM or MRI tool can be placed have unique source and/or steel framing geometries that necessitate a custom cancellation geometry to effectively cancel a disturbing field.
We consider the concepts of magnetic flux path analysis and source geometry to debug and troubleshoot magnetic field issues. Mu metal shielding, flux containment, electrical current routing, and active cancellation are the tools we use to mitigate magnetic disturbances.
- Sensitivity Testing Topics Include:
Overview, Floor Vibration Sensitivity, Acoustic Noise Sensitivity, Magnetic Field Sensitivity