Microgate picks Vicor to power ESO’s Extremely Large Telescope adaptive optics
Microgate is collaborating with the European Southern Observatory (ESO), an intergovernmental research organisation for ground-based astronomy, to construct the adaptive mirror for the latest and largest generation of Extremely Large Telescopes (ELTs). Microgate picked Vicor to provide the DC-DC converter power modules to power the adaptive optics used by this unique mirror.
ELTs serve as the epicentre for discovering new galaxies, stars, and planets. The primary challenge facing these telescopes is to capture light from the distant past to gain further insights into the origins of our Universe.
Based in the Atacama Desert in Chile, the new ELT being developed by the ESO will have a pioneering five-mirror optical design that will allow it to unveil the Universe in unprecedented detail. It will capture 20 times more light than a Very Large Telescope (VLT). The primary mirror, M1, comprised of hundreds of individual hexagonal segments, will be by far the largest ever made for an optical telescope. This giant 39-metre concave mirror will collect the scarce photons available from distant stars and galaxies and reflect them to the secondary mirror (M2).
The convex M2, the largest secondary mirror ever employed on a telescope, will be positioned above M1 and will reflect light back down to M3, which in turn will then relay it to an adaptive flat mirror (M4) situated above it. This fourth mirror will adjust its shape a thousand times per second to correct for distortions caused by atmospheric turbulence before directing the light to M5 — a flat tiltable mirror that will stabilise the image and transmit it to the ELT instruments.
The adaptive M4 mirror
The M4 mirror is the largest deformable mirror ever constructed. Its surface can be distorted and adapted to correct for atmospheric turbulence and the residual vibrations of the telescope itself. Here, the ELT will employ sophisticated ‘adaptive optics’ technologies to compensate for the turbulence of the Earth’s atmosphere and to ensure its images are sharper than those of any other telescope. It will also include other components, such as a prefocal station that serves as the link between the telescope and its instruments. Lastly, it will feature a modern control system to enable the user to operate the telescope for scientific observations and maintenance activities.
The ESO-ELT M4 mirror is 2.4 metres in diameter and is made of highly specialised glass with a thickness of about 1.9 millimetres. The mirror uses voice-coil motors that are driven by a precise current driver and a series of co-located permanent magnets to provide the necessary force to deform the mirror. This process is performed across the entire surface of the mirror using 5,316 motors, each with an inter-axis distance, or pitch, of about 30 millimetres.
The adaptive M4 mirror physically floats on the magnetic field generated by the motor coils. This allows a dedicated control current to locally deform the mirror and correct the shape using an equivalent number of highly-sensitive capacitive or position sensors with an accuracy in the nanometer (millionth of a millimetre) range. Using electronic systems which operate at a frequency of about 100 kHz, Microgate engineers can completely redefine the shape of the mirror in one millisecond. The result is an extremely sharp and cleanly rendered image without having to launch a telescope into space.
Vicor power-dense modules
Precise manipulation and thermal management of the adaptive optics system is critical and requires all exposed surfaces to be kept close to ambient temperature to avoid local turbulence. The power system challenge is made even more difficult by the limited space.
Vicor’s DCM3623 series of DC-DC converter power modules was specifically selected by Microgate to power this process. The power system board is mounted on the underside of the gas-cooled cold plate, and each module powers up to 36 motor channels, eliminating complex wiring.
“Vicor’s high-efficiency and high-power density modules are very compact and reliable and take up very little space on the circuit board,” said Gerald Angerer, Hardware Engineer at Microgate. “These miniaturised power converters are the best option for us. We have been using them for more than 10 years, and there is currently no comparable substitute.”
Further information on the ESO Extremely Large Telescope
www.vicor.com
www.microgate.it/en
If you enjoyed this article, you will like the following ones: don't miss them by subscribing to :
