- document
-
Huisman, R. (author), Paalvast, S. (author), Brandl, B.R. (author), van den Dool, T.C. (author), Eggens, M. (author), Janssen, H. (author), Aitink-Kroes, G. (author), Molster, F. (author), Teuwen, M. (author), Venema, L. (author), Jayawardhana, B. (author)We present the main results of the performance test campaign of the Mid-Infrared European Extremely Large Telescope Imager and Spectrograph (METIS) Cold Chopper Demonstrator (MCCD). This tip/tilt mirror, which operates at a temperature of 77 K, is one of the critical components in the METIS for the European Extremely Large Telescope. The...article 2016
- document
-
Navarro, R. (author), Elswijk, E. (author), te Voert, M.J.A. (author), Venema, L. (author)NOVA-ASTRON has delivered a suite of cryogenic astronomical instruments for large ground based telescopes as well as space missions. The instruments include polarimeters, spectrometers, cameras and interferometers, mostly operating at infrared. Several methods have been developed to verify or measure, under cryogenic conditions, the performance...conference paper 2014
- document
-
Agócs, T. (author), Navarro, R. (author), Venema, L. (author), van Amerongen, A.H. (author), Tol, P.J.J. (author), van Brug, H. (author), Brandl, B.R. (author), Molster, F. (author), Todd, S. (author)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...conference paper 2014
- document
-
van Amerongen, A.H. (author), Agocs, T. (author), van Brug, H. (author), Nieuwland, G. (author), Venema, L. (author), Hoogeveen, R.W.M. (author)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...conference paper 2012
- document
-
Korkiakoski, V. (author), Venema, L. (author), Agocs, T. (author), Keller, C.U. (author), Doelman, N.J. (author), Fraanje, P.R. (author), Andrei, R. (author), Verhaegen, M. (author)We investigate the potential of phase-diversity (PD) and Gerchberg-Saxton (GS) algorithms in the calibration of active instruments. A set of images is recorded with the focal-plane scientific camera, each image having a known and unique defocus. The phase-retrieval algorithms are used, with those images, to estimate the non-common path...conference paper 2012
- document
-
van Dalen, E.J. (author), Groen, S. (author), van Houtert, L. (author), Jansen, B. (author), Leede J. de, (author), Oegema, K. (author), Peltzer, F. (author), van de Riet, A. (author), van Tuyl, J. (author), Venema, L. (author), Vos, P. (author), Walter J., (author), van Zandvoord, E. (author)Zelf je eigen werktijden bepalen, zo luiden de krantenkoppen die over zelfroosteren gaan. Het is een fenomeen dat recent in de media en bij werkgevers en werknemers veel aandacht trekt. Zelfroosteren zou zowel de werkgever als de werknemer voordelen bieden. Maar kan dat wel, een rooster zonder nadelen? De werkelijkheid is ingewikkelder dan een...book 2009