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Heason Technology has been awarded a contract by Synchrotron Soleil to design a system for a soft X-ray scanning photo-emission microscope project called Antares.

Heason is to design and manufacture four nanopositioning manipulators that combine as a 14-axis ultra-high vacuum and low magnetic motion system.

Antares will provide the scientific community with the means to examine structures at the atomic level and will be of benefit to pioneering research in soft condensed matter in areas of interest such as microelectronics and nanotechnology.

Antares will include a powerful scanning photo-emission microscope (SPEM) technique that will use the Heason-designed manipulators to focus the beam and perform sample scanning with nanometre precision in combination with three independent detectors producing precise sample mapping, revealing the location of the elements, their relative abundances and their chemical state.

Antares’ motion requirements involve linear and rotary positioning of the sample with a five-axis nanometre resolution manipulator in combination with three separate, three-axis, beam modification manipulators to ensure nanometre-level linear alignment of the specialist optical system, which comprises several Fresnel zone plates, an order sorting aperture (OSA) and a pinhole.

Each of the four manipulators will be arranged on an intricate adapter plate system to effectively form a single assembly, which is housed inside a 550mm inner-diameter vacuum chamber that also includes a granite isolation plate base, laser interferometer optics, and various other components including complex detector systems.

The challenge to design a customised solution within the severe space restriction of the ultra-high vacuum chamber is intensified by the need to limit magnetic materials throughout the manipulators’ bearing and mechanical support system as well as restrict motor heat to within a desired operational temperature and range of 25C, +/-1C with vacuum bake-out temperatures up to 120C.

Heason will choose ceramic servomotor technology from its specialist partner Nanomotion to ensure the high-precision motion, non-magnetic and low thermal characteristics for each manipulator axis, including both rotary positioners for sample positioning.

The Nanomotion ceramic motor has the ability to hold and lock position with zero position shift when power is removed to further ensure temperature stability.

Each axis will include Renishaw optical encoders with either 0.1 or 0.05 micron feedback resolution to ensure the overall positioning specification is achieved.

To maintain the low magnetic requirement, ensure the high stiffness and minimise harmonic sensitivity within the positioning system, specialised stainless-steel cross roller bearings with low magnetic permeability will be used.

Where possible, within the tight dimensions provided by the vacuum chamber, all axes will include over-travel switches and datum position switches for homing the complete assembly.

Heason will also provide the customer with detailed manufacturing and electrical scheme documentation, design and motor sizing calculations, and material selection information for the complete project.

Throughout the design phase, Heason design engineers will liaise with Synchrotron Soleil scientists and engineering teams to develop the final design in conjunction with the selection of other specialised components that will also be housed in the vacuum chamber.

The design specification includes areas that require detailed evaluation before a final specification can be defined.

One such area is the provision of a single vertical axis for the sample positioner, which is used to set a course position at initial set-up and will be satisfied with a stepper motor drive.

During the design phase Heason will carry out full evaluation to determine whether this motor is to be located within or outside the vacuum chamber.

The contract also includes full acceptance tests and site visits to Synchrotron Soleil to assist with installation.

During the design phase and at installation, Heason will also liaise with Synchrotron Soleil’s motion control system supplier to provide specialist software support.

This includes developing an auto-homing routine so that all axes can safely establish a datum position without collision, and a thermal prediction program for each the ceramic motors based upon duty cycle and environmental conditions.

These requirements will also be pre-calculated and determined using a separate motion controller at Heason Technology during the design phase with the main parameters transferred to Synchrotron Soleils’ existing motion control system.

The expected installation date for the complete system is during the autumn of 2009 with acceptance tests and full commissioning by early 2010.

Heason Technology

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