Walter Bien / Thomas Rauschenbach / Birgit Riedel (Hrsg.): Wer betreut Deutschlands Kinder? Berlin, Düsseldorf, Mannheim: Cornelsen Scriptor 2006 (317 S.) [Rezension]

Rezension von: Walter Bien / Thomas Rauschenbach / Birgit Riedel (Hrsg.): Wer betreut Deutschlands Kinder? Berlin, Düsseldorf, Mannheim: Cornelsen Scriptor 2006 (317 S.; ISBN 3-589-24518-5; 29,90 EUR)

Using the Gerchberg-Saxton algorithm to reconstruct non-modulated pyramid wavefront sensor measurements

Adaptive optics (AO) is a technique to improve the resolution of ground-based telescopes by correcting, in real-time, optical aberrations due to atmospheric turbulence and the telescope itself. With the rise of Giant Segmented Mirror Telescopes (GSMT), AO is needed more than ever to reach the full potential of these future observatories. One of the main performance drivers of an AO system is the wavefront sensing operation, consisting of measuring the shape of the above mentioned optical aberrations. Aims. The non-modulated pyramid wavefront sensor (nPWFS) is a wavefront sensor with high sensitivity, allowing the limits of AO systems to be pushed. The high sensitivity comes at the expense of its dynamic range, which makes it a highly non-linear sensor. We propose here a novel way to invert nPWFS signals by using the principle of reciprocity of light propagation and the Gerchberg-Saxton (GS) algorithm. We test the performance of this reconstructor in two steps: the technique is first implemented in simulations, where some of its basic properties are studied. Then, the GS reconstructor is tested on the Santa Cruz Extreme Adaptive optics Laboratory (SEAL) testbed located at the University of California Santa Cruz. This new way to invert the nPWFS measurements allows us to drastically increase the dynamic range of the reconstruction for the nPWFS, pushing the dynamics close to a modulated PWFS. The reconstructor is an iterative algorithm requiring heavy computational burden, which could be an issue for real-time purposes in its current implementation. However, this new reconstructor could still be helpful in the case of many wavefront control operations. This reconstruction technique has also been successfully tested on the Santa Cruz Extreme AO Laboratory (SEAL) bench where it is now used as the standard way to invert nPWFS signal

Characterization of diamond-turned optics for SCALES

High-contrast imaging has been used to discover and characterize dozens of exoplanets to date. The primary limiting performance factor for these instruments is contrast, the ratio of exoplanet to host star brightness that an instrument can successfully resolve. Contrast is largely determined by wavefront error, consisting of uncorrected atmospheric turbulence and optical aberrations downstream of AO correction. Single-point diamond turning allows for high-precision optics to be manufactured for use in astronomical instrumentation, presenting a cheaper and more versatile alternative to conventional glass polishing. This work presents measurements of wavefront error for diamond-turned aluminum optics in the Slicer Combined with an Array of Lenslets for Exoplanet Spectroscopy (SCALES) instrument, a 2-5 micron coronagraphic integral field spectrograph under construction for Keck Observatory. Wavefront error measurements for these optics are used to simulate SCALES' point spread function using physical optics propagation software poppy, showing that SCALES' contrast performance is not limited by wavefront error from internal instrument optics.Comment: Techniques and Instrumentation for Detection of Exoplanets X

Update on the Preliminary Design of SCALES: the Santa Cruz Array of Lenslets for Exoplanet Spectroscopy

SCALES (Santa Cruz Array of Lenslets for Exoplanet Spectroscopy) is a 2-5 micron high-contrast lenslet integral-field spectrograph (IFS) driven by exoplanet characterization science requirements and will operate at W. M. Keck Observatory. Its fully cryogenic optical train uses a custom silicon lenslet array, selectable coronagraphs, and dispersive prisms to carry out integral field spectroscopy over a 2.2 arcsec field of view at Keck with low ($<300$) spectral resolution. A small, dedicated section of the lenslet array feeds an image slicer module that allows for medium spectral resolution ($5000-10 000$), which has not been available at the diffraction limit with a coronagraphic instrument before. Unlike previous IFS exoplanet instruments, SCALES is capable of characterizing cold exoplanet and brown dwarf atmospheres ($<600$ K) at bandpasses where these bodies emit most of their radiation while capturing relevant molecular spectral features.Comment: 24 pages, 13 figures, SPIE Astronomical Instruments and Telescopes 2020 conferenc

Thomas Walsh, Primary Education in Ireland, 1897-1990. Curriculum and Context. Oxford, Bern, Berlin, Bruxelles, Frankfurt am Main, New York, Wien: Peter Lang 2012 (466 S.) [Rezension]

Rezension von: Thomas Walsh, Primary Education in Ireland, 1897-1990. Curriculum and Context. Oxford, Bern, Berlin, Bruxelles, Frankfurt am Main, New York, Wien: Peter Lang 2012 (466 S.; ISBN 978-3-0343-0751-2

Wolfgang Einsiedler / Margarete Götz / Christian Ritzi / Ulrich Wiegmann (Hrsg.), Grundschule im historischen Prozess. Zur Entwicklung von Bildungsprogramm, Institution und Disziplin in Deutschland. Bad Heilbrunn: Klinkhardt 2012 (310 S.). [...] [Sammelrezension]

Sammelrezension von: 1. Wolfgang Einsiedler / Margarete Götz / Christian Ritzi / Ulrich Wiegmann (Hrsg.), Grundschule im historischen Prozess. Zur Entwicklung von Bildungsprogramm, Institution und Disziplin in Deutschland. Bad Heilbrunn: Klinkhardt 2012 (310 S.; ISBN 978-3-7815-1837-7). 2. Johannes Jung / Bettina König / Katharina Krenig / Katrin Stöcker / Verena Stürmer / Michaela Vogt (Hrsg.), Die zweigeteilte Geschichte der Grundschule 1945 bis 1990. Ausgewählte und kommentierte Quellentexte zur Entwicklung in Ost- und Westdeutschland. Berlin: LIT 2011 (262 S.; ISBN 978-3-643-11087-9). 3. Johannes Jung, Der Heimatkundeunterricht in der DDR. Die Entwicklung des Faches in den unteren vier Jahrgangsstufen der Polytechnischen Oberschule zwischen 1945 und 1989. Bad Heilbrunn: Klinkhardt 2011 (163 S.; ISBN 978-3-7815-1817-9

Joachim Scholz, Die Lehrer leuchten wie die hellen Sterne. Landschulreform und Elementarlehrerbildung in Brandenburg-Preußen. Bremen: edition lumière 2011 (266 S.) [Rezension]

Rezension von: Joachim Scholz, Die Lehrer leuchten wie die hellen Sterne. Landschulreform und Elementarlehrerbildung in Brandenburg-Preußen. Bremen: edition lumière 2011 (266 S.; ISBN 978-3-934686-86-1

Frank Hellmich (Hrsg.): Lehr-Lernforschung und Grundschulpädagogik. Bad Heilbrunn: Klinkhardt 2008 (282 S.) [Rezension]

Rezension von: Frank Hellmich (Hrsg.): Lehr-Lernforschung und Grundschulpädagogik. Bad Heilbrunn: Klinkhardt 2008 (282 S.; ISBN 978-3-7815-1633-5; 19,90 EUR)

Dietmut Kucharz / Matthea Wagener: Jahrgangsübergreifendes Lernen. Eine empirische Studie zu Lernen, Leistung und Interaktion von Kindern in der Schuleingangsphase. Baltmannsweiler: Schneider Hohengehren 2007 (171 S.) [Rezension]

Rezension von: Dietmut Kucharz / Matthea Wagener: Jahrgangsübergreifendes Lernen. Eine empirische Studie zu Lernen, Leistung und Interaktion von Kindern in der Schuleingangsphase. Baltmannsweiler: Schneider Hohengehren 2007 (171 S.; ISBN 978-3-8340-0199-3; 16,00 EUR)