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Aerotech’s engineered motion subsystem has been selected for an ultra-precision plate scanner at the Royal Observatory of Belgium.

The Damian ultra-precision scanning system at the Royal Observatory of Belgium (ROB) fulfils a significant part of a global programme for the digitisation of astrometric plates and aerial photographic images that span more than a century.

The programme was borne out of a need to provide a centralised archive to enhance the accuracy of predictive ephemerides and to preserve the heritage of this work where media deterioration is an increasing problem.

One particular exacting project example at the ROB involves digitising thousands of photographic plates for the US Naval Observatory.

Taken over a period of 30 years several decades ago, using a 26in refractor telescope, the photographs record the moons of Mars, Jupiter and Saturn.

By combining the process with sophisticated measurement and prediction software, Damian can actually fill in many gaps that have previously been difficult to calculate.

By improving this understanding of the interactive motions and internal structure models of these Solar System bodies, the accuracy of calculation for their future positions over time is significantly improved.

Other work carried out has similar significant implications for galactic kinematics, space surveillance and other areas of research in high-precision aerial mapping.

The ROB began development of the Damian (Digital Access to Metric Images Archives Network) digitiser with a study that produced design specifications for a 350mm x 350mm X-Y scanning motion system.

To ensure the perfect reproducibility of the original analogue photographic images, the positional accuracy and repeatability targets needed to be an order above the inherent accuracy for the plates.

This value was interpreted in the region of 0.5 microns over the whole scanning area with respect to a fixed telecentric objective of a sophisticated digital camera system.

To ensure the fastest possible throughput, the motion system required a full move displacement of 10mm in less than half a second, including acceleration, deceleration and settling time, and once in position, the stability (jitter) requirement was just 20 nanometres.

These factors would ensure that the plates could be fully scanned and archived in a matter of minutes rather than older methods that were less accurate and required hours of processing.

The machine specification also called for automatic loading of the glass photographic plates and film rolls, with a working duty cycle close to 24/7 continuous and unattended operation – so high reliability, low maintenance and long working life were also critical factors.

To realise such extreme precision and dynamic performance, the ROB chose Aerotech for a complete motion subsystem based upon its ABL3600 series open-frame air bearing table in a custom engineered system solution.

The system included a lapped granite base plate, a granite bridge with a vertical focussing axis for the camera and optical assembly, plus a photographic plate holder, plate storage tower and fully automatic transport system.

Now delivered and fully commissioned, the Damian digitiser is housed in a temperature and humidity-controlled clean room, maintained to within 0.1C and one per cent RH.

Aerotech’s ABL3600 series X-Y stage includes a preloaded, high-stiffness air bearing system that features dual brushless and slotless linear motors on each axis with glass-scale linear encoder servo feedback.

Two granite rails form a reference for the lower axis and both axes are referenced to a lapped granite surface plate with passive air isolation to maximise vibration stability.

In combination with this positioning system and fundamental to the machine’s overall dynamic performance, Aerotech said its linear technology servo amplifiers guarantee smooth motion, high bandwidth and in-position stability with zero backlash or hysterisis.

The friction-free mechanics also provide the added benefit of very low maintenance and an essentially limitless working life.

The large through aperture of the open-frame design allows back illumination for the plates and images.

The design of the ABL3600 has applications in semiconductor fabrication and test, and is a suitable for demanding scanning microscopy, imaging and step-and-repeat positioning applications.

For the ROB, Aerotech extended the ABL3600’s normal working travel range from 250mm to 350mm in both axes.

For such high-precision applications, Aerotech’s Halar calibration firstly ensures optimal levels of accuracy, bi-directional repeatability, straightness and flatness for each axis, then performs error mapping with laser-based measurement systems at Aerotech’s metrology lab – with the calibration file pre-configured on the motion controller.

During tests at Aerotech and on site at the ROB, object locations on a calibrated test plate were repeated to within 70 nanometres over a usable X-Y travel range of 335mm – this far exceeded the original working specification.

Other results included geometric test for accuracy and repeatability to better than +/- 0.1 micron and the displacement speed and in-position stability performance were fully met.

The Damian ultra-precision scanning system includes a full cable management system and was delivered complete with Aerotech’s A3200 automation platform motion control system, which controls the main X-Y axes as well as several other motion axes for film wind, plate stacking and tray height adjustment.

The ROB took care of interfacing the A3200 to its own imaging software using a step-and-repeat procedure with alignment accuracy ensured using selected objects on the photographic media.

Images are recorded at standstill, thus the need for such high in-position stability.

The PC-based software-only motion and machine controller provides position, velocity and time information to Firewire interfaced linear technology servo drives.

A range of optional modules include HMI, soft PLC and vision control.

The fully deterministic controller can be programmed using Aerotech’s own Aerobasic, RS274 G-code and Labview.

Alternatively, programmers can use the Microsoft .Net development environment to help reduce project development timescales with C, C++, Visualbasic or Delphi-based programming.


Aerotech — manufacturer of high-precision motion control components and systems

Aerotech — manufacturer of high-precision motion control components and systems

Aerotech manufactures the highest-performance motion control components and systems for our customers in industry, government, science and research institutions around the world. Our products include automated nanopositioners; planar and rotary air-bearing stages; high-speed gantries; mechanical-bearing linear, rotary and lift stages; brushless linear and rotary servomotors and drives; standalone and software-based motion controllers; goniometers; and gimbals/optical mounts. Custom, vacuum-prepped and cleanroom-ready positioning systems and components are available. Aerotech’s precision motion control products provide the critical performance for demanding applications in markets including medical devices and life sciences, semiconductors and flat panels, photonics, automotive, data storage, laser processing, military and aerospace, electronic manufacturing and test, assembly, research and development and others requiring high-precision, high-throughput motion solutions.

Motion controls, drives and motors

From our award-winning Automation 3200 32-axis machine controller to our Soloist series single-axis and Ensemble series multi-axis standalone motion controllers, Aerotech provides a controller solution to fit almost any need. Aerotech complements our controllers with our large selection of high-performance brushless linear and rotary servomotors and PWM and linear drives.

Linear and rotary stages, nanopositioners and gantries

Aerotech positioning stages range from economical ballscrew and gear-driven linear and rotary stages to the highest-performance direct-drive linear and rotary stages available, linear-motor-based Cartesian gantry systems, single- and multi-axis air-bearing systems and our complete range of ANT series long-travel nanopositioners.

Custom, vacuum and cleanroom-ready motion systems

If you don’t find a standard product suitable for your application, our expertise and ability to provide custom motion components and systems is unmatched. Our custom manufacturing capability is further augmented by our long history of providing systems for vacuum and cleanroom operation.

Since 1970, Aerotech has been committed to supporting our customers worldwide. We maintain a growing number of direct field sales and engineering offices throughout the US, as well as representatives across the globe. We also operate full sales and service facilities in the UK, Germany, Japan, Taiwan and China.

We’d be happy to assist you with your motion control application. Please use the contact information below to enquire about our services.

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