P R O J E C T   O V E R V I E W :

ELT Laser Guide Stars

credit: ESO

UH2.2 Meter Telescope Adaptive Secondary Mirror

MAIT manager for the UH2.2 Adaptive Secondary Mirror (ASM).

When observing the sky from the ground, images of stars and galaxies are distorted by the turbulence in the Earth’s atmosphere. To reduce these effects, modern observatories are equipped with adaptive optics (AO) systems. AO uses a bright reference star, close to the observed object. The blurring of the reference star is measured with a wavefront sensor, enabling a deformable mirror to correct the atmospheric distortions. TNO and industrial partners VDL ETG, AAC Hyperion and Fraunhofer IPT have developed a deformable mirror for the University of Hawaii (UH) 2.2-meter telescope secondary mirror. The UH2.2 Adaptive Secondary Mirror (ASM) design is based on a novel hybrid variable reluctance actuator with high efficiency, resulting in a compact system without the need for active cooling. The high actuator efficiency enables the use of a relatively thick and robust face sheet. The ASM can be retro-fitted within the same mass and space envelope of the existing passive UH2.2 secondary mirror.

UH2.2 Adaptive Secondary Mirror

credit: TNO/B. Dekker

VLT Laser Guide Star Launch Telescopes

Project manager, procurement manager and AIT manager for the Laser Launch Telescopes of the 4LGSF for the Very Large Telescope (VLT) at TNO.

The Laser Guide Star forms a part of the new adaptive optics (AO) system of the UT4 telescope. The AO system corrects for atmospheric turbulence disturbances, thereby vastly increasing the useful resolution of the telescope.

 

The 4 LGSF consists of a high power 25 W CW 589 nm laser, a Beam Conditioning and Diagnostics System (BCDS) and an Optical Tube Assembly (OTA). OTA is a 20x Galilean beam expander, with a 15 mm diameter input beam and a steerable 300 mm diameter collimated output beam. OTA employs four optical elements, a Quarter Wave Plate, a small double concave L1 lens, a Field Selector Mirror and a highly aspherical 380 diameter mm L2 lens. The design is passively athermalized over a large temperature range as well as under the influence of thermal gradients.
To achieve 4.8 arcmin radius field of view on-sky, the FSM has to tilt up to ±6.1 mrad, in combination with less than 1.5 µrad RMS absolute accuracy. The FSM design consists of a Zerodur mirror, bonded to a membrane spring and strut combination to allow only tip and tilt. Since the range is too large for piezos, two (self-locking) spindle drives actuate the mirror, using a stiffness based transmission to increase resolution. Absolute accuracy is achieved with two differential inductive sensor pairs.

 

 

 

VLT Laser Guide Star

credit: ESO/Fred Kamphues

VLT 4LGSF OTA

credit: ESO/Fred Kamphues

GAIA Basic Angle Monitoring system

Consultancy for TNO for the development of a Basic Angle Monitoring Opto Mechanical Assembly for GAIA. The Gaia mission will create an extraordinarily precise three-dimensional map of more than one billion stars in our Galaxy. Part of ESA's Cosmic Vision programme, the Gaia spacecraft was built by EADS Astrium and launched on December 19, 2013. TNO has developed the all Silicon Carbide Basic Angle Monitoring Opto-Mechanical Assembly (BAM OMA) for this mission.

 

The GAIA satellite measures the angles between stars using two telescopes set at a fixed angle of 106.5°, named the Basic Angle. The astrometric measurements will be accurate to 24 microarcsec (at 15 magnitude), comparable to measuring the diameter of a human hair at a distance of 1000 kilometres. This requires ultra high stability, which can only be achieved by using Silicon Carbide for the optical bench and telescopes. In addition the Basic Angle variation shall be measured within a precision of 0.5 microarcsec. Therefore GAIA is equipped with a Basic Angle Monitoring subsystem, a metrology system to monitor the angle between the two telescopes. This system consists of two laser interferometers. Two pairs of parallel laser bundles are sent to the two telescopes, which create two interference patterns on a detector. If the basic angle varies, the interference patterns will shift. With the BAM an Optical Path Difference (OPD) as small as 1.5 picometers RMS can be measured.

 

credit: TNO/Fred Kamphues

VLT Interferometer Delay Line

Assembly, Integration and Testing (AIT) manager and lead mechanical engineer for the overall mechanical design of the first three Delay Lines for the Very Large Telescope Interferometer (VLTI) for ESO, under the responsibility of Fokker Space (see also ESO press release).

The work consisted of the design of highly accurate mechanical components, with strong links to other disciplines (optics, electronics and software), as well as final adjustment of mechanical components of the first VLTI Delay Line at the VLT facility in Paranal, Chile.

 

VLTI delay lines in the tunnel at Cerro Paranal

credit: ESO/Fred Kamphues

 P U B L I C A T I O N S : 

• Development of a laser projection system for the ELT, Jan Nijenhuis et al, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V, 29 August - 6 September 2022, Montréal, QC, Canada, 1218837 (1218837)

• Manufacturing and integration status of the UH2.2 adaptive secondary mirror, Wouter Jonker et al, Proceedings Volume 12188, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V; 1218816 (2022), SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

• Hot forming of a large deformable mirror facesheet, Wouter Jonker et al, Proceedings Volume 12188, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V; 121880S (2022), SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

• Preliminary design of the Adaptive Secondary Mirror for the European Solar Telescope, Stefan Kuiper et al, Proceedings Volume 12185, Adaptive Optics Systems VIII; 1218528 (2022),SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

• Warping Harness actuator for the Thirty Meter Telescope Primary Mirror segments, F. Kamphues et al, SPIE Proceedings Volume 11451, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV; 1145150 (2020)

• Harnessing The Next Generation Of Extremely Large Telescopes, L. Visser et al, Mikroniek Nr. 4 2017

• 30 M Diameter for 7 milli-arcsec resolution, F. Kamphues, Mikroniek Nr. 6 2016

• Damping in space constructions, Jan de Vreugd et al, European Conference on Spacecraft Structures, Materials & Environmental Testing, Braunschweig, April 2014

• Star Separators for the Very Large Telescope Interferometer - Increasing sensitivity for distant planets and supermassive black holes, J. N. Nijenhuis et al, Mikroniek, Vol. 53, issue 3, June 2013

• Design, analysis, and testing of the optical tube assemblies for the ESO VLT four laser guide star facility, SPIE Volume 8447-172, July 2012

• Gaia basic angle monitoring system, SPIE Volume 8442-61, July 2012

• Optical Tube Assemblies for the ESO VLT Four Laser Guide Star Facility, Second international conference on Adaptive Optics for Extremely Large Telescopes, Victoria, BC, Canada, September 2012.

• Athermal design of the Optical Tube Assemblies for the ESO VLT Four Laser Guidestar Facility (Conference Proceedings Paper), Optical Engineering + Applications, SPIE Volume 8149-04, August 2011.

• Picometer metrology for the GAIA mission (Conference Proceedings Paper), Astronomical and Space Optical Systems, SPIE Volume 7439, August 2009

• Corrective polishing of strongly curved aspheric silicon carbide mirrors (Conference Proceedings Paper), SPIE Optifab, May 2009

• Picometer metrologie voor de Gaia missie, NVR Ruimtevaart 2009-2

• Astronomische Telescopen, article in NVPT Yearbook 2009, November 2008, NVPT 

• Pico Meter Metrology for Gaia mission, International Conference on Space Optics (ICSO) 2008, October 2008 

• Picometre metrology in space, article in Mikroniek, periodical for precision technology, June 2008

• Picometer metrology for the Gaia mission (Conference Proceedings Paper), Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter, 12 July 2008, SPIE Volume 7010

• Simultaneous observation of two stars using the Prima Star Separator (Conference Proceedings Paper), Space Telescopes and Instrumentation 2008: Instruments, July 2008, SPIE Volume 7013

• PACT: the actuator to support the primary mirror of the E-ELT (Conference Proceedings Paper), Space Telescopes and Instrumentation 2008: Segment mirror technologies, July 2008, SPIE Volume 7018

• The development of a breadboard cryogenic optical delay line for Darwin (Conference Proceedings Paper), Cryogenic Optical Systems and Instruments XII, 66920A, 17 September 2007, SPIE Volume 6692

• The development of a breadboard cryogenic optical delay line for Darwin, 12th European Space Mechanisms and Tribology Symposium (ESMATS) 2007

• Darwin - Een optische vertragingslijn voor een ruimtetelescoop, NVPT Yearbook 2007, text: Ben Braam, Teun van den Dool, Fred Kamphues

• The DARWIN breadboard optical delay line verification programme (Conference Proceedings Paper), Advances in Stellar Interferometry, 62682O, 28 June 2006, SPIE Volume 6268

• The Darwin Breadboard Cryogenic Optical Delay Line, Sixth International Conference on Space Optics, Proceedings of ESA/CNES ICSO 2006, held 27-30 June 2006 at ESTEC, Noordwijk, The Netherlands. Edited by A. Wilson. ESA SP-621. European Space Agency, 2006.

• The manufacturing, assembly and acceptance testing of the breadboard cryogenic optical delay line for DARWIN, SPIE  Conference Optics and Photonics [5904- p. 367-377], August 2005, San Diego, USA

• The development of a cryogenic delay line for DARWIN, ICMENS  Conference, July 2005, Banff, Canada

• Magnetic Bearing optical delay line,  SPIE Conference Optical Science and Technology [5528A-37], August 2004, Denver, USA

• Metrology concept design of the GAIA basic angle monitoring system,  SPIE Conference Astronomical Telescopes and Instrumentation SPIE [5495-02], june 2004, Glasgow, UK

• DARWIN cryogenic optical delay line, SPIE Conference Astronomical Telescopes and Instrumentation [5495-40], June 2004, Glasgow, UK

• Advanced optical delay line demonstrator, SPIE Conference Astronomical Telescopes and Instrumentation [5495-41], June 2004, Glasgow, UK

• Test results of the VLTI delay line system verification program, H. Hogenhuis, Fokker Space B.V. (Netherlands), SPIE Conference Astronomical Telescope and Instrumentation [4006-22], March 2000, Munich, Germany

Mikroniek 2022-5

credit: DSPE/ESO/Fred Kamphues