1. High resolution magnetoresistive position sensor for the JWST Tobias Junginger

2. Contents The JWST  Scientific goals  Instruments Nirspec (near infrared spectrograph)  Microshutters  The Grating wheel position sensor

3. The James Webb Space Telescope Infrared space telescope scheduled for launch in 2013 large mirror 6.5 meters in diameter and a sunshield the size of a tennis court Both will fold up in space Orbit second sun-earth Langrangian point (1,5 million kilometers from earth)

5. Scientific goals Identify the first bright objects that formed in the early Universe Assembly of Galaxies The birth of stars and protoplanatary systems study the physical and chemical properties of solar systems

6. Instruments TypeWavelength Nircam imager with a large field of view and high angular resolution 0,6-5 μm Miri imager/spectrograph 5-27 μm Nirspec Spectrograph 1-5 μm

9. The Micro-shutters

10. The GWA (Grating Wheel Assembly)

11. The GWA Position Sensor

12. Can measure two dimensions Ready for using at a wide temperature range down to 4K High sensitivity in movement direction (0,3 arcsec) Low impact on the sensitivity by small deflections in Z axis Minimal power dissipation No forces in movement direction Compact size and very lightweight design (fieldplates + magnets < 10g) The GWA Position Sensor Requirements

13. The GWA Position Sensor Breadboard Michelson Interferometer Light Input from Laser Light output to photo diode Mount for the fieldplates Mount for the magnets Piezoelectric positioning unit