History

The company NOB Neutron Optics Berlin GmbH was founded in 2000 as a spin-off from the neutron optics group at the Hahn-Meitner-Institut Berlin, HMI, (now Helmholtz-Zentrum Berlin, HZB) to commercially exploit the accumulated know-how in the field of supermirrors and other neutron optical elements.
The concept of neutron supermirrors was first published by Ferenc Mezei in 1976 [1], [2]. In his group at the HMI Thomas Krist developed since 1986 neutron supermirrors, polarisers and collimators starting with Ni-Ti supermirrors and then polarising FeCo-Si and Fe-Si supermirrors [3].
With these supermirrors, many different devices were realised which are used at the HMI as well as at other research facilities worldwide. The polarising supermirrors were used for reflection and/or transmission polarisers [4], [5], [6], [7]. Later they were used to build solid-state benders in which the neutrons travel inside thin Si wafers which are coated with polarizing and absorbing layers [8]. In the beginning, these benders had the traditional C-shape but since about 2012 the polarisation efficiency of solid state benders was improved to values of 98% and above by using S-shape benders [9].
The analysing efficiency of a supermirror is limited to an angular divergence in the order of its critical angle. To overcome this limitation, radial benders were built which allow analysing also in the second dimension a wide angular range of neutrons scattered from a line source [10]. Also, the concept of the radial cavity was invented for this purpose [11].
In another development, inversely polarising Co-Cu supermirrors were built for the first time which reflect the spin down instead of the spin up component [12]. Also, solid-state collimators were built for the first time, including collimators with purely absorbing walls as well as with walls coated with a reflecting layer below the absorbing one [13]. This leads to a rectangular transmission function which results in an increased transmission without reducing the resolution. Radial collimators were realised as well [14]. Also, a solid state lens was tested which allows focusing neutron beams [15].


In 2016 NOB started to do research in the field of x-ray optics, supported by two substantial grants.
Attention to the dispersive properties of off-axis reflection zone plates (RZP) first arose in 1994.
They were applied as spectrometer elements in hard [16] and soft [17] X-ray radiation experiments to facilitate spectral analysis of laser - plasma sources. In the case of the soft X-ray range, the effect of total external X-ray reflection from super polished surfaces was applied, instead of Bragg reflection on a crystal or multilayer. Demonstrated first in [18], an RZP spectrometer for absorption spectroscopy on transition metals was built to facilitate measurements with nanosecond acquisition times This considerably increased the energy range of a dispersive element due to the polychromatic nature of reflection from a smooth surface, which is not limited by the energy selectivity of Bragg reflection.
With modern developments in methods for the study of ultra-fast material processes with the use of synchrotron radiation (SR), X-ray free-electron lasers (FEL) and laboratory sources, such as high-harmonic generators (HHG) and laser-plasma sources (LPS), Fresnel reflection optics have found wide application. Unique properties of reflective Fresnel optics or reflection zone plates (RZP) have proven to be useful in optical schemes for parallel spectrometers based on scanning electron microscopes (SM) [19] and ultra-high time resolution SR systems [20]. In addition to the possibility of Fourier time-energy resolution optimization, a combination of reflection, dispersion, and focusing in a single element increases the transmission efficiency of
optical schemes by orders of magnitude, as additional optical elements are not required to produce collimated beams or refocus them in conventional spectroscopy layouts.
For the fabrication of the RZP, the most advanced methods of nanotechnology were applied. The new ideas for RZP spectrometer designs could not be realized without associated nanotechnology advances. In [21], for the first time, e-beam lithography with a high-performance pattern generator was applied for the fabrication of reflective Fresnel structures. In comparison with other methods, the e-beam technique in combination with dry etching facilitated the production of three-dimensional diffraction structures with varying line space densities exceeds 1000% and line density up to 5000 l/mm with any required diffraction line shape.
The new technology step, fabrication of 3-D diffraction structures on curved substrates, promises considerable improvements for spectrometer and monochromator efficiency, resolution and energy range. Development of this technology will give possibilities for the design and construction of compact monochromators and spectrometers with unique parameters. 3-dimensional RZP can replace two or three elements in an optical scheme and, therefore, reduce absorption losses by several orders of magnitude.


In 2018 the company was renamed to NOB Nano Optics Berlin GmbH.

 

References


[1] F. Mezei, Novel polarized neutron devices: supermirror and spin component amplifier; Communications on Physics 1 (1976) 81.
[2] F. Mezei, P. A. Dagleish, Corrigendum and first experimental evidence on neutron supermirrors; Communications on Physics 2 (1977) 41.
[3] T. Krist, C. Lartigue, F. Mezei: Transmission geometry supermirror neutron polarizer device;
Physica B 180 & 181 (1992) 1005-1006.
[4] Th. Krist, C. Pappas, Th. Keller, F. Mezei:The polarizing beam splitter guide at BENSC; Physica B 213 & 214 (1995) 939-941.
[5] Th. Krist, F. Klose, G. P. Felcher: A white beam neutron spin splitter; Physica B 248 (1998) 372-376.
[6] T. Keller, T. Krist, A. Danzig, U. Keiderling, F. Mezei, A. Wiedenmann: The polarized neutron small angle scattering instrument at BENSC Berlin; Nucl. Instr. and Methods in Phys. Res. A 451 (2000) 474-479.
[7] Th. Krist, C. Pappas, A. Teichert, C. Fehr, D. Clemens, E. Steichele and F. Mezei: New polarizing
guide for neutron wavelengths above 2.5 Å; J. Phys.: Conf. Ser. 251 (2010) 012081.
[8] Th. Krist, S. J. Kennedy, T. J. Hicks, F. Mezei: New compact neutron polarizer; Physica B 241-243 (1998) 82-85.
[9] Th. Krist, F. Rucker, G. Brandl, R. Georgii: High performance, large cross section S-bender for neutron polarization; Nuclear Inst. and Methods in Physics Research A 698 (2013) 94-97.
[10] Th. Krist, H. Fritzsche, F. Mezei: Large-angle neutron polarisation analyser; Appl. Phys. A 74 [Suppl.] (2002) s221-s223.
[11] Péter Falus, Alexei Vorobiev, Thomas Krist: Test of a two-dimensional neutron spin analyser; Physica B 385-386 (2006) 1149-1151.
[12 ]Th. Krist, J. Hoffmann, P. Schubert-Bischoff, F. Mezei: Inversely polarizing Co-Cu neutron
supermirrors; Physica B 241-243 (1998) 86-88.
[13] Th. Krist and F. Mezei: High performance, short solid state collimators with reflecting walls; Nucl. Instr. and Methods in Phys. Res. A 450 (2000) 389-390.
[14] Markus Bleuel, Ed Lang, Thomas Krist, Werner Wagner and Jyotsana Lal: SANSPOL at a Pulsed Source; Physica B 397 (2007) 85-87.
[15] R. Bartmann, N. Behr, A. Hilger and Th. Krist: New solid state lens for reflective neutron focusing; Nuclear Instruments and Methods in Physics Research A 634 (2011) S104–S107.
[16]Ya.Faenov, S.A. Pikuz, A.I. Erko, B.A. Bryunetkin, V.M. Dyakin, G.V. Ivanenkov, A.R. Mingaleev, T.A. Pikuz, V.M. Romanova, T.A. Shelkovenko, PhysicaScripta, 50, 333-338, (1994)..
[17] T.Wilhein, D. Hambach, B. Niemann, M. Berglund, L. Rymell, and H. M. Hertz, Appl. Phys. Lett. 71, 190-192 (1997).
[18] U. Vogt, M. Wieland, T. Wilhein, M. Beck, and H. Stiel, Rev. Sci. Instrum. 72(1), 53 – 57 (2001).
[19] A Erko, A Firsov, R Gubzhokov, A Bjeoumikhov, A Günther, N Langhoff, M. Bretschneider, Y. Höhn, R. Wedell, Optics Express, 22 (14), 16897-16902, (2014).
[20] M. Brzhezinskaya, A. Firsov, K. Holldack, T. Kachel, R. Mitzner, N. Pontius, J.-S. Schmidt, M.
Sperling, C. Stamm, A. Föhlisch, A. Erko J. Synchrotron Rad. (2013). 20, 522-530
[21] S.V. Babin, A.I. Erko, Fabrication of diffraction X-Ray Elements, Nuclear Instruments and Methods in Physics Research, A282, 529-531, (1989)

 

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