1. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 EUS NI spectrograph design constraints EUS NI spectrograph design constraints Udo Schühle Max-Planck-Institute for Solar System Research Solar Orbiter 5th EUS consortium Meeting at RAL on 3. March 2006 Contents: 1.design of normal-incidence spectrograph with ZEMAX 2.optical quality of the single-mirror off-axis telescope 3.possibility of three wavelength ranges between 58 nm and 126.8 nm 4.design of focal plane with 116.8 nm to 126.8 nm channel 5.some thoughts on thermal aspects: a)Semi-transparent telescope mirror b)Heat rejection mirror

2. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 Based on previous design of Roger Thomas: development of varied-line-space grating surface for ZEMAX ZEMAX calculation with ellipsoid VLS grating modified RT design for longer wavelength channel verified the design complies with specs some possible thermal design solutions normal-incidence design optical calculations normal-incidence design optical calculations

3. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 off axis parabola telescope: aperture size: 70 mm distance from vertex: 50 mm focal length: 700 mm image scale: 1arcsec = 3.4 microns spectrograph: grating: varied-line-space on ellipsoid magnification: 3.6 image scale:12  m/arcsec dispersion: 5 A/mm spectral scale:60 mA/12  m (40 mA/8  m) 1 arcsec Design of NI spectrograph Design of NI spectrograph

4. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 Design of single-mirror telescope Design of single-mirror telescope 1 arcsec off axis parabola telescope: aperture size: 70 mm distance from vertex: 50 mm focal length: 700 mm image scale: 1arcsec = 3.4 microns

5. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 favoured wavelength ranges :52 nm – 63 nm 72 nm – 80 nm 97 nm – 104 nm 116.5 nm – 126.8 nm possible with siliconcarbide optics normal incidence design with three wavelength ranges from 58.0nm to 126.8nm Accommodation of three wavelength bands possible? Accommodation of three wavelength bands possible?

6. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 900 mm 70 mm TVLS grating - 71.0 nm - 80.0 nm - 116.5 nm (58 nm) - 126.8 nm (63 nm) - 97.0 nm - 104.5 nm 700 mm Accommodation of three wavelength bands possible! Accommodation of three wavelength bands possible! 250 mm slit

7. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 Accommodation of long-wavelength band Accommodation of long-wavelength band He I O VMg X O IV C III Si III N VC I Si I Mg X

8. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 Accommodation of long-wavelength band Accommodation of long-wavelength band More useful dynamic range with selective photocathode distribution Presentation of wavelength channels to be given by Luca Teriaca

9. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 Study of a dichroic telescope mirror for 58 nm up Study of a dichroic telescope mirror for 58 nm up mirror coating for wavelengths 58 nm and up: SiC (CVD, hex) a thin coating of ~10 nm provides good VUV reflectivity of 35% to 45% longer wavelengths can be transmitted by a transparent substrate mirror temperature can be minimised detailed thermal study is possible.  dichroic telescope mirror can transmit 90% of the heat!

10. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 Study of a dichroic telescope mirror for 58 nm up Study of a dichroic telescope mirror for 58 nm up Calculations of David Windt 2001 using optical constants of SiC

11. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 Study of a dichroic telescope mirror for 58 nm up Study of a dichroic telescope mirror for 58 nm up ==> heat will be transmitted towards a radiator 10 nm SiC on LiF substrate* * calculation using optical constants of Palik et al. independent study is ongoing with samples of SiO 2 and SiC coating of 5 nm, 10 nm, 20 nm thickness

12. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 Design of single-mirror telescope: heat rejection mirror and baffle Design of single-mirror telescope: heat rejection mirror and baffle  field of incident radiation at slit plane: +-2.6° (= size of solar image + pointing range)  corresponds to circular range of 64 mm diameter!  unpredictable thermal distortions during orbit and pointing changes  unpredictable stray light in front of the spectrometer slit  toroidal pre-slit mirror

13. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 Design of single-mirror telescope: heat rejection mirror and baffle Design of single-mirror telescope: heat rejection mirror and baffle radiator toroidal heat rejection mirror

14. Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 900 mm 70 mm TVLS grating - 75.0 nm - 85.0 nm - 97.0 nm - 104.0 nm 700 mm Thermal baffle design requires space for heat rejection mirror Thermal baffle design requires space for heat rejection mirror 250 mm slit heat rejection mirror - 116.5 nm (58 nm) - 126.8 nm (63 nm)