qinetiq chris dorn lightweight optics for extreme uv spectrometer 9 july 2002

QinetiQChris DornLightweight optics for Extreme UV Spectrometer9 July 2002

Medium Wave Infra Red (MWIR)Space Telescope

Pushing technology harder

3

Copyright QinetiQ 2002

Dead Pixels

M1

Railway and station

A5(T) Grand Union Canal

MWIR

Pixels: 35m

Orbit: 450 x 1750km, 69°

Milton Keynes 12th August 2000 14:42 UTC

Level 2 processing;

stagger bar re-sampling

TopSat

RutherfordAppletonLaboratory

A new chapter in optical missions

5


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

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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

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Results

• Interferogram of:-

– “flat” CFC mirror

– unpolished

• The Spherical Mirror is

– more accurate

– has been polished

• ~5.6 kg/m2

– Topsat 164 kg/m2

– Hubble 180 kg/m2

ALCAMIST(Adaptive Lightweight CArbon MIrror SysTem)

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ALCAMIST• Faraday Partnership project,

Smart Optics

• 55cm adaptive mirror

• CFC faceplate

• 19 actuators

• Greater understanding of:-– CFC mirrors– Manufacturing issues– Practical problems

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Timeline

1995 20111997 1999 2001 2003 2005 2007 2009

EUS Phase B

start

Now Launch

MWIR

LW mirrorsALCAMIST

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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; [email protected]

qinetiq chris dorn lightweight optics for extreme uv spectrometer 9 july 2002

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