1. HELAS, Nice 27 September 2006 Visible light Imager and Magnetograph T.Appourchaux on behalf of the VIM team IAS

2. HELAS, Nice 27 September 2006 Contents Scientific objectives Instrument design Instrument challenges What now ?

3. HELAS, Nice 27 September 2006 Scientific objectives Probe the Solar Dynamo: –High-latitude fields, flows and seismic waves Explore at all latitudes: –Energetics, dynamics and fine-scale structure of the Sun’s magnetized atmosphere Investigate links: –Between the solar surface, corona and inner heliosphere

4. HELAS, Nice 27 September 2006 Stereoscopic helioseismology

5. HELAS, Nice 27 September 2006 What are the observables? High and low resolution imaging Vector magnetic field Solar radial velocities

6. HELAS, Nice 27 September 2006 How can we do that? High and low resolution imaging –Full Disk Telescope (FDT), Field of view >2.5 deg, 2.5 cm dia. –High Resolution Telescope (HRT), 150 km resolution at 0.22 AU (1”), Field of view >15, 16 cm dia; Vector magnetic field –Stokes polarimetry in FeI 6173 Angström Solar radial velocities –5 to 6 positions on the line profile

7. HELAS, Nice 27 September 2006 VIM: Subsystems FDT: –Off-pointing mechanism: wedge prism (2.5 deg) HRT: –Image Stabilization System (0.02” overs 10 s) –Filtergraph (passband of 75 mAngström) –Polarization modulation package (PMP based on Liquid Crystal Variable Retarder) Camera: 2k x 2k Active Pixel Sensor Electronic box

8. HELAS, Nice 27 September 2006 The VIM team Germany: –PI ship, management, HRT, Structure:MPS –Pointing: KIS Spain: –FDT, PMP: INTA –E-box: IAA –Structural and thermal analysis: IDR France: –Filtergraph: IAS

9. HELAS, Nice 27 September 2006 Filtergraph concept Telecentric –No velocity change –Passband shifted and widened –All defects imaged on the solar image –Aperture apodization Baseline solution: Lithium Niobate Fabry-Pérot, 6 cm dia. Back-up: Fabry-Pérot with piezoelectric spacers

10. HELAS, Nice 27 September 2006 Tunability requirement (TN-VIM-2005-02 and 03)

11. HELAS, Nice 27 September 2006 Response (TN-VIM-2005-01)

12. HELAS, Nice 27 September 2006

13. Challenges Space qual. of LCVR Space qual. Of LiNb0 3 etalons High solar flux 25 solar constant… Reduced telemetry: 20 kbits/s

14. HELAS, Nice 27 September 2006 What now ? Call for Letter of Intent (ESA, 11 July 06) MPS response as of 15 September 06 Heat Shield study till end 2007 AO hopefully in 2008 Launch in 2017 Observation till 2023-2028…