The opto-mechanical performance prediction of thin mirror segments for E-ELT

The mirror segments for the E-ELT and TLT are nearly equal in size and shape (hexagonal, 1.2 m over flat sides). They are very thin (about 50 mm) compared to their size. Supporting these mirrors and obtaining high optical performance is a challenge from design and manufacturing point of view. TNO has designed and build (together with VDL-ETG)...

Designing the primary mirror support for the E-ELT

Described is the M1 segment support, as designed by TNO in the period 2015- 2016. The design has significantly changed and improved compared to the earlier designs. During the period 2009-2010 prototypes for the primary mirror support of the E-ELT have been developed. These have been extensively tested by ESO. Design improvement were found to be...

Primary mirror control for large segmented telescopes: Combining high performance with robustness

Future large telescopes, such as E-ELT and TMT, will need feedback control of the thousands of actuators underneath their segmented primary mirrors (M1). Differences in actuator dynamics and spatially and temporally changing disturbances make it extremely diffcult to formulate classical controllers which are both suffciently robust and highly...

Nanometre-accurate form measurement machine for E-ELT M1 segments

To enable important scientific discoveries, ESO has defined a new ground-based telescope: the European Extremely Large Telescope (E-ELT). The baseline design features a telescope with a 39-m-class primary mirror (M1), making it the largest and most powerful telescope in the world. The M1 consists of 798 hexagonal segments, each about 1.4 m wide,...

Design of an E-ELT M1 segment measurement machine with nanometer accuracy

The baseline design of the European Extremely Large Telescope features a telescope with a 39-meter-class primary mirror (M1), consisting of 798 hexagonal segments. A measurement machine design is presented based on a non-contact single-point scanning technique, capable of measuring the form error of each segment with nanometer uncertainty, fast,...

High performance control of mirror segment actuators for the European Extremely Large Telescope

Segmented primary mirror telescopes require dedicated piston-tip-tilt actuators for optimal optical performance. TNO has developed various prototypes of such actuators, in particular for the E-ELT. In this paper the control results of a specific two-stage prototype will be presented.

A set of innovative immersed grating based spectrometer designs for METIS

We present innovative, immersed grating based optical designs for the SMO (Spectrograph Main Optics) module of the Mid-infrared E-ELT Imager and Spectrograph, METIS. The immersed grating allows a significant reduction of SMO volume compared to conventional echelle grating designs, because the diffraction takes place in high refractive index...

Development of silicon immersed grating for METIS on E-ELT

We have developed the technology to manufacture an immersed grating in silicon for the Mid-infrared E-ELT Imager and Spectrograph, METIS. We show that we can meet the required diffraction-limited performance at a resolution of 100000 for the L and M spectral bands. Compared to a conventional grating, the immersed grating drastically reduces the...

PACT: the actuator to support the primary mirror of the ELT

The European Southern Observatory (ESO) has started technology development for their next generation optical telescope. Due to its ultra large collecting area, The European Extremely Large Telescope (E-ELT) will require a paradigm shift in telescope design to keep the overall program cost at an acceptable level. The E-ELT will feature a 42 meter...