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European Extremely Large Telescope

Operational in 2024

Recently, the first sod was turned for the E-ELT telescope in the Atacama desert in Chile. It will become the world’s largest optical telescope.

The E-ELT uses CANopen-connected servo-controllers to position the telescope’s mirrors (Photo: National Instruments)

Chilean President Michelle Bachelet inaugurated the construction of the E-ELT. Located on a 3000-m high mountain, the optical telescope will start operations as an integral part of the Paranal Observatory in 2024. The telescope is said to be five times larger than many of its existing counterparts. With its enormous size, the E-ELT could change our perspective of the universe, according to its backers, who are optimistic about the performance of the telescope's primary mirror that can measure some 39 m across.

"The E-ELT will vastly advance astrophysical knowledge by enabling detailed studies of planets around other stars, the first galaxies in the Universe, super-massive black holes, and the nature of the Universe's dark sector," European Southern Observatory (ESO) said on its website. The active optics comprise a control system and combination of sensors and actuators so that the telescope can maintain the correct mirror shape or collimation. The positioning precision is about 1 nm.

Labview and PXI hardware by National Instruments (NI) positions the primary mirror. The actuator application is composed of a module in the NI PXIe-8130 real-time controller and a module in the PXI-7842R FPGA card. The real-time software includes the functionality of each actuator – initial self-checking, a state machine, a status word, an error register, and the management of configurable parameters. Other tasks carried out include checking input coming from the FPGA card with serial peripheral interface (SPI) external commands, implementing the coarse stage servo-controller to be transmitted via a CANopen network to a brushless motor driver. Via the CANopen network the servo-controllers receive commands, which provide information about the end of stroke switches and hardware warnings.


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