AXRO, DECEMBER X-ray Optics: Wolter versus KB system Veronika Marsikova a, Libor Sveda b, Adolf Inneman a, Jiri Marsik a, Rene Hudec c, Ladislav Pina b a) Rigaku Innovative Technologies Europe, s.r.o. b) Czech Technical University in Prague, FNSPE c) Astronomical Institute of Academy of Sciences of Czech Republic

AXRO, DECEMBER Motivation Manufacturing Wolter system needs very expensive mandrels (3D aspheric). Manufacturing KB system can be easier and cheaper (2D aspheric). Substrates can be glass and/or silicon with excellent flatness and micro-roughness which is necessary for long focus optics.

AXRO, DECEMBER Wolter system Double reflection X-ray Optics - Wolter type I optics consists of rotationally symmetric mirrors which are parabolic mirror followed by a hyperbolic mirror. Set of nested mirrors is arranged concentrically to the optical axis. Each ray coming is reflected at the parabolic surface first, then at the hyperbolic surface. The quality of the focal spot image of the X- ray source depends on quality of substrates (shape, microroughness). Optical error is rectified (astigmatic and coma error). Replicated technology requires very expensive mandrel. XMM

horizontal focusing mirror vertical focusing mirror AXRO, DECEMBER KirckPatrick Baez system Double reflection X-ray Optics consists of two mirror sets – one is aligned vertically and the second is aligned horizontally. Both mirrors have to be curved parabolically – the first mirror focuses in vertical plane and the second mirror focuses in horizontal plane. Single focal point is formed in the crossection of the two focal planes. The quality of the focal spot image depend on quality of substrates (shape, microroughness). Technology is not necessarily based on precise and expensive mandrel. Classic technologies for laboratory KB- mirrors are expensive, complicated and based on heavy optics.

Design and simulation AXRO, DECEMBER 20095

6 Comparison KBW Type of opticsParabolic-parabolic planarParabolic-hyperbolic rotational Number of reflections22 Focal length - Aperture 20 m – 913 x 913 mm 40 m – 1826 x 1826 mm 10 m – dia 913 mm 20 m – dia 1826 mm First mirror 134 mm from axis 268 mm from axis 134 mm from axis 268 mm from axis Number of mirrors Length of substrate300 mm Material substratesiliconglass Surfacegold

AXRO, DECEMBER Focal length W system KB system If W and KB have the same aperture, focal length of KB system is twice as large as Wolter system. L 2L

AXRO, DECEMBER Input conditions Minimum distance between mirrors: 1 mm Energy range: 1.0 – 10.0 keV Last mirror reflection: 70% reflection (after 1 st 1keV) ‏ 50% reflection (after 2 nd 1keV) ‏

AXRO, DECEMBER Aperture optics system KB system W system

AXRO, DECEMBER Reflectivity at first mirror set (Focal length 10m KB and 20m W) ‏ KB system W system

AXRO, DECEMBER Source spectrum Crab Nebula Images of Crab Nebula from Chandra X-ray Observatory. Physics News Graphics, AIP. Toor & Seward (1974)

AXRO, DECEMBER Off-axis source images (Focal length 10m KB and 20m W) ‏ KB systemW system

AXRO, DECEMBER Off-axis source images (Focal length 20m KB and 40m W) ‏ KB systemW system

Focal peak intensity – not normalized AXRO, DECEMBER

Focal peak intensity - normalized AXRO, DECEMBER

Focal FWHM [mm] – not normalized AXRO, DECEMBER

Focal FWHM [arcsec] – normalized AXRO, DECEMBER

Focal length optimization AXRO, DECEMBER “ideal” focal length for both sets results in asymmetric peak focal length of mirror set one was optimized Difference ideal- optimal ~ 4 mm

Next year enhancements Reflectivity efficiency maps. Segment based KB design as a result of efficiency maps (flower-like KB) ‏. Comparison to standard designs. AXRO, DECEMBER

Flower – like KB AXRO, DECEMBER

Manufacturing AXRO, DECEMBER

AXRO, DECEMBER RITE technologies Based on industrial substrates (glass and or Si wafer) with very good surface quality (shape, microroughness) => low cost. Technology process retains surface quality and polishing process is not needed. Technology allows composite materials and/or relatively light- weight materials. Cubic geometry means easer assembling of the system. Gorenstein, Paul,Proc. SPIE Vol. 3444, p

ISRO Meeting Prague, October MFO technology X-ray optics –Substrates Glass Silicon Nickel –Type of optics KB system Lobster Eye

Si substrates AFTERBEFORE

AXRO, DECEMBER Si substrates Analysis of formed Si wafer by TH profilometer. Analysis of formed Si wafer by AFM. Comparison of convex side of bent Si wafers (left) and flat Si wafer (right)

AXRO, DECEMBER RITE modules Model based on ray-tracing (11 profiles) ‏ Two sets of mirrors from Si chips 100x100x0.525 mm Total optics length 600 mm, aperture 40x40 mm

Tests AXRO, DECEMBER

AXRO, DECEMBER Conclusion KB vs. W Comparable effective area at f=2*f KB has more homogeneous intensity KB has comparable angular resolution KB samples manufactured from multiple small Si chips (substrates) Tests are expected at the beginning of 2010 Future enhancements of KB (simulation + manufacturing – silicon and glass substrates)

AXRO, DECEMBER Acknowledgment We acknowledge support of: Grant Ministry of Education, Youth and Sports, grant “Applications of Kirkpatrick Baez Imaging Systems in Space”, No. ME Grant ESA - PECS, grant “Novel X-ray Optics Technologies for ESA X-ray Astrophysics Missions”, No Grant Agency of Academy of Sciences of the Czech Republic, grant “Material and X-Ray Optical Properties of Formed Silicon Monocrystals”, No. IAAX Project MSMT INGO “Vyzkum v ramci Mezinarodniho centra husteho magnetizovaneho plasmatu”.

AXRO, DECEMBER THANK YOU FOR YOUR ATTENTION.