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Preliminary imaging tests of lobster eye optics for nano-satellite

Preliminary imaging tests of lobster eye optics for nano-satellite. Vladim ír Tichý, Marco Barbera, Alfonso Collura, Martin Hromčík, René Hudec, Adolf Inneman, Jiří Maršík, Veronika Maršíková, Ladislav Pína, Vojtěch Šimon. Czech Technical University in Prague

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Preliminary imaging tests of lobster eye optics for nano-satellite

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  1. Preliminary imaging tests of lobster eye optics for nano-satellite Vladimír Tichý, Marco Barbera, Alfonso Collura, Martin Hromčík, René Hudec, Adolf Inneman, Jiří Maršík, Veronika Maršíková, Ladislav Pína, Vojtěch Šimon Czech Technical University in Prague Universitá degli Studi di Palermo INAF-Osservatorio Astronomico di Palermo Rigaku Innovative Technologies Europe, s.r.o. Academy of Sciences of the Czech Republic

  2. Lobster eye • Grazing incidence reflective X-ray optics • Schmidt design1: two sets of reflective surfaces - each set focuses in one plane • Wide field of view: up to ~100 square degrees • Can have small mass and dimensions Prototype lobster eye P-25, manufactured and provided by Rigaku Innovative Technologies Europe, s.r.o. [1] W. H. K. Schmidt, ”A proposed X-ray focusing device with wide field of view for use in X-ray astronomy”,Nucl. Instr. Meth. 127, 285-292 (1975)

  3. Lobster eye principle One-dimensional system:Flat mirrors are arranged in an uniform radial pattern around the perimeter of a cylinder. or Two orthogonally arranged systemsin sequence form double-focusing device Another LE prototype, also manufactured by Rigaku Innovative Technologies Europe, s.r.o.

  4. Prototype Lobster Eye P-25 • Manufactured and provided by Rigaku Innovative Technologies Europe, s.r.o. • Focal length 250mm • Outer dimensions 35G35G50 mm • Consists of 2G60 mirrors of diameters 24G24G0.1 mm • Optimal efficiency at 1 keV X-ray photon energy • Similar parameters we suppose for LE for nano-satellite

  5. Proposed application X-ray all-sky monitor like ASM/RXTE Preparatory goal Smaller and cheaper nano-satellite mission giving the practical proof of the LE technology. Questions Is that mission technologically feasible? Could nano-satellite lobster eye mission acquire scientifically relevant data?

  6. What the nomenclature “nano-satellite” does mean • Usually, the nomenclature nano-satellite means satellite of dimesions of orderof 10 cm and maximum mass of few kilograms. • Especially, the platform called CubeSat defines the base unit as a cube of dimensions of 10×10×10 cm3 and its maximal mass is limited to 1 kg. • Moreover, it is allowed to build specified multiples of the base unit, possible sizes are 0.5, 1.5, 2 and 3 times of the base unit. So, the whole spacecraft can have total dimensions 30×10×10 cm3 and total mass up to 3 kg.

  7. Tests of P-25 in X-rays Lobster eye P25 was tested in quasi parallel beam full imaging mode using the 35 meters long X-ray beam line in XACT facility of INAF-Osservatorio Astronomico di Palermo(Italy). X-ray images at the focal plane have been taken with a MCP detector with spatial resolution 100μm.

  8. Experimental setup Tested lobster eye was placed on device allowing remote controlled rotations figured by red color. MCP detector was placed on device allowing remote controlled translations in all directions.

  9. Simulations • One-dimensional system: The sufficient problem is to calculate shades and reflections of individual mirrors D1 = M1b − (M1z − Dz) tan() D2 = M4b − (M4z − Dz) tan() D1b = M1b − (M1z − I1z) tan(2 + ) D2b = M2b − (M2z − I2z) tan(2 + )  = −   = arctan[(M2b −M1b)/(M2z −M1z)]

  10. Shading between mirrors M’1z = (N2b − q1)/t M’1b = M2b M’2z = (q1 − q2)/t M’2b = tM’2z + q1 t = (M2b −M1b)/(M2z −M1z) q1 = M1b − tM1z q2 = N1b − 2tN1z One-dimensional system => one-dimensional martrix Two-dimensional system => outer product of these matrices

  11. Basic images 280eV 930eV 1500eV 2900eV 4500eV 8000eV

  12. Gain • Calculated as measured ratio between the flux incoming to LE and the measured averageflux of X-rays measured in the projection of the central chamber of size 300×300μm Simulations Experiment

  13. Spatial resolution Estimated FWHM spatial resolution 13±1 arcmin. If sum profile of the image with the shifted one to simulate profile of image of two point sources and if we find the limit when the intesity between peaks fall to 80% of intesity of peak level, we get the same value. Theoretical value is 5.5 arcmin.

  14. Field of view At the boundary positions, gain is decreased to approx. 1/2 Angle between boundary chambers is 2.8º Experimentally found boundary positions => FOV = 2.9±1º Yaw = -1.4˚ Yaw = +1.5˚

  15. Explanation There are some manufacturing deviation causing the smearing of the image. However, it is a common problem of any technology. Question: Can we still do some astronomical observations with this or similar lobster eye?

  16. Mission assumptions Field of view Measured value is in agreement with the theoretical. So, we can belive our model. Supposing manufacturing of larger LE, with active area of 8G8cm, we could reach FOV of 5G5º. Sensitivity The effective active area calculated from the incoming flux and the total amount of photons focused to spot (defined via FWHM) reaches 0.38cm2. We are conservative and we will suppose this value is unchanged. Also, we suppose 30% quantum efficiency of a used detector achievable for example using an MCP. We simply suppose the object is detected if at least 100 photons are focussed into spot. These very conservative assumptions based on measured values gives the minimal flux to be detected using 1ks exposure time as 1.4 × 10−9 erg cm−2 s−1≈ 60 mCrab

  17. Relevant scientific goal We could monitor low- and high-mass X-ray binaries (LMXBs and HMXBs) in area of 5G20º around the Galactic center. For this goal, also measured angular resolution around 13 arcmin is sufficient. The field of the center of the Galaxy (20×80º). The positions of known LMXBs and HMXBs are marked.The field proposed for the monitoring by lobster is marked by the oblong. It contains a number of the already knownLMXBs and HMXBs.

  18. Example #1: The light curve of a persistent source GX 3+1 observed by ASM/RXTE is in the 1.5-3 keV band. Example #2: The outburst of a transient source Aql X-1 observed by ASM/RXTE in the 1.5-3 keV band.

  19. Conclusions • Although we reported differences between the theoretical and measured values, presented results still indicatethat the proposed lobster eye nano-satellite mission is feasible using known and verified technologies. • Low and high mass X-ray binaries (LMXBs and HMXBs) laying in thecenter of the Galaxy seem to be good targets for the observations.

  20. Acknowledgnments • Thanks Prof. Salvatore Sciortino, director of INAF-Osservatorio Astronomico di Palermo • Thanks to Rigaku Innovative TechnologiesEurope s.r.o. for providing of the lobster eye specimen.

  21. Thank you for your attention

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