QinetiQ Chris Dorn Lightweight optics for Extreme UV Spectrometer 9 July 2002

Medium Wave Infra Red (MWIR) Space Telescope Pushing technology harder

Copyright QinetiQ Dead Pixels M1 Railway and station A5(T)Grand Union Canal MWIR Pixels: 35m Orbit: 450 x 1750km, 69° Milton Keynes 12 th August :42 UTC Level 2 processing; stagger bar re-sampling

TopSat A new chapter in optical missions

Copyright QinetiQ TopSat - overview 2.5m target resolution, panchromatic baseline + 3 band colour at 5m 15% system MTF, 50:1 SNR 15km FoV 1 year mission life Near real time operations In-theatre demonstration Launch planned 2004

Copyright QinetiQ Lightweight Optics Variety of materials tested Carbon fibre selected, due to:- –High specific stiffness –“Controllable” CTE –Low cost –Relatively simple process Coatings technologies –Durable –Polishable Zerodur 24 x 28cm, 4300g CFC 28cmØ, 250g

Copyright QinetiQ Results Interferogram of:- –“flat” CFC mirror –unpolished The Spherical Mirror is –more accurate –has been polished ~5.6 kg/m 2 –Topsat 164 kg/m 2 –Hubble 180 kg/m 2

ALCAMIST (Adaptive Lightweight CArbon MIrror SysTem)

Copyright QinetiQ ALCAMIST Faraday Partnership project, Smart Optics 55cm adaptive mirror CFC faceplate 19 actuators Greater understanding of:- –CFC mirrors –Manufacturing issues –Practical problems

Copyright QinetiQ Timeline EUS Phase B start Now Launch MWIR LW mirrors ALCAMIST

Copyright QinetiQ Post Meeting Notes/Comments Following our attendance at the Cosener’s House meeting, several issues, questions, actions and comments arose:- –Some further work is recommended to define the physical dimensions of the science module, so that only viable optical designs are investigated. –Further work is recommended on the realistic electrical noise environment within the detector and ADC (including quantisation noise). By setting an acceptable signal to noise ratio, the suitability of optical designs can be evaluated. –Consideration should be given to novel observation strategies that are limited by the data transfer and instrument power limitations, while simplifying the thermal management situation. Eg. looking away from the sun or use a shutter to reduce solar input. –The operating temperature range for a “typical” carbon fibre (eg. EX1515/M46J) has been qualified for space at +120°C to -170°C. Our materials specialists suggest that +200°C is probbaly achievable with that resin/matrix system, however, they have not been tested at such temperatures. The advatnageof composite materials is that the resin and matrix can be selected for the expected conditions and several alternative resin/matrix systems are available that have been tested to significantly higher tempeatures. The ALCAMIST technology allows a mirror to be adjusted over this temperature range, hence maintaining optical requirements. A short test programme to demonstrate this and suitable coatings would ensure that this technology was available for consideration in the design. –With optical systems, there are 2 main design routes; fixed and adaptive. Engineering a “fixed” optical system (on a 2m scale) that remains within tolerance over such a wide operating temperature range and within a realistic mass budget is extremely risky. By following the adaptive or “smart structure” route, the changes in the optical system can be sensed and corrected. This trades mass for technical complexity, but careful selection of mature technologies will minimise this. An ALCAMIST style mirror can also provide the raster scan function. –My contact details;