149 research outputs found
Invariance of waveguide grating mirrors to lateral displacement phase shifts
We present a method to analyse the coupling of lateral displacements in
nanoscale structures, in particular waveguide grating mirrors (WGM), into the
phase of a reflected Gaussian beam using a finite-difference time-domain
simulation. Such phase noise is of interest for using WGMs in high-precision
interferometry. We show that WGMs do not couple lateral displacements into the
phase of a reflected beam to a precision of 10^{-7} rad and that WGMs are
therefore not subject to the same stringent alignment requirements as
previously proposed layouts using diffraction gratings.Comment: 3 Pages, 4 figure
Realization of a monolithic high-reflectivity cavity mirror from a single silicon crystal
We report on the first experimental realization of a high-reflectivity cavity
mirror that solely consists of a single silicon crystal. Since no material was
added to the crystal, the urgent problem of 'coating thermal noise' that
currently limits classical as well as quantum measurements is avoided. Our
mirror is based on a surface nanostructure that creates a resonant surface
waveguide. In full agreement with a rigorous model we realized a reflectivity
of (99.79+/-0.01)% at a wavelength of 1.55 {\mu}m, and achieved a cavity
finesse of 2784. We anticipate that our achievement will open the avenue to
next generation high-precision experiments targeting fundamental questions of
physics.Comment: Phys. Rev. Lett., accepte
Biomasseaufbereitung zur Vergärung - Aufarbeitung landwirtschaftlicher Biomasse für den Vergärungsprozess
Die Studie »Aufarbeitung landwirtschaftlicher Biomasse für den Vergärungsprozess« zeigt, dass eine dem Vergärungsprozess vorgeschaltete Aufarbeitung landwirtschaftlicher Biomasse mittels Doppelschneckenextruder, Multischroter oder Enzymen die Energieproduktion um bis zu 26,6 % steigern kann. Die beispielhafte Darstellung von Aufarbeitungsmöglichkeiten anhand einer Biogasanlage mit 500 kWel beweist, dass sich die Biogaserzeugung beim Einsatz von Maissilage lohnen kann. Eine Rentabilitätserhöhung ist dabei kaum ersichtlich, es kann jedoch mit frei werdender Anbaufläche für die Nahrungsmittelproduktion gerechnet werden. Eine wirtschaftliche Biogaserzeugung auf der Basis vorzerkleinerter Grassilagen konnte nicht nachgewiesen werden, lediglich eine deutliche Effizienzsteigerung. Wie sich die Gewinnerwartung bei zunehmendem Gülleanteil bei Grassilage verhält sowie ausführliche Betrachtungen der Versuche und deren Wertung lesen Sie im kompletten Ergebnisbericht
Geoarchaeology of Taman Peninsula (Kerch Strait, South-West Russia) – the Example of the Ancient Greek Settlement of Golubitskaya 2
In the framework of an extensive archaeological survey and excavation programme on Taman Peninsula, geoarchaeological research was carried out in this terra incognita of the north-eastern Black Sea region. In the present study, a small area was surveyed in detail with respect to its geomorphological and archaeological situation. Geoarchaeological scenarios were generated for the last seven millennia. For the first time, the sea level rise and its effect on the landscape could be documented in time and space, showing, among others, that Taman Peninsula had evolved out of an archipelago
Denoising Diffusion Probabilistic Models for Generation of Realistic Fully-Annotated Microscopy Image Data Sets
Recent advances in computer vision have led to significant progress in the
generation of realistic image data, with denoising diffusion probabilistic
models proving to be a particularly effective method. In this study, we
demonstrate that diffusion models can effectively generate fully-annotated
microscopy image data sets through an unsupervised and intuitive approach,
using rough sketches of desired structures as the starting point. The proposed
pipeline helps to reduce the reliance on manual annotations when training deep
learning-based segmentation approaches and enables the segmentation of diverse
datasets without the need for human annotations. This approach holds great
promise in streamlining the data generation process and enabling a more
efficient and scalable training of segmentation models, as we show in the
example of different practical experiments involving various organisms and cell
types.Comment: 9 pages, 2 figure
All-reflective coupling of two optical cavities with 3-port diffraction gratings
The shot-noise limited sensitivity of Michelson-type laser interferometers
with Fabry-Perot arm cavities can be increased by the so-called power-recycling
technique. In such a scheme the power-recycling cavity is optically coupled
with the interferometer's arm cavities. A problem arises because the central
coupling mirror transmits a rather high laser power and may show thermal
lensing, thermo-refractive noise and photo-thermo-refractive noise. Cryogenic
cooling of this mirror is also challenging, and thus thermal noise becomes a
general problem. Here, we theoretically investigate an all-reflective coupling
scheme of two optical cavities based on a 3-port diffraction grating. We show
that power-recycling of a high-finesse arm cavity is possible without
transmitting any laser power through a substrate material. The power splitting
ratio of the three output ports of the grating is, surprisingly, noncritical
Логіка
Зміст видання відповідає освітньо-професійній програмі бакалаврів
напрямів підготовки «Право», «Філософія» та інших напрямів.
Розглянуто матеріал дисципліни «Логіка», зокрема такі теми: «Основні
закони формальної логіки», «Поняття», «Судження», «Умовиводи»,
«Доведення і спростування», «Гіпотеза і теорія».
Сформульовано навчальні цілі змістових модулів дисципліни, що
окреслюють компетентності, навички й уміння бакалавра гуманітарних та
інших спеціальностей
Sonification of Arm Movements in Stroke Rehabilitation – A Novel Approach in Neurologic Music Therapy
Waveguide grating mirror in a fully suspended 10 meter Fabry-Perot cavity
We report on the first demonstration of a fully suspended 10m Fabry-Perot
cavity incorporating a waveguide grating as the coupling mirror. The cavity was
kept on resonance by reading out the length fluctuations via the
Pound-Drever-Hall method and employing feedback to the laser frequency. From
the achieved finesse of 790 the grating reflectivity was determined to exceed
99.2% at the laser wavelength of 1064\,nm, which is in good agreement with
rigorous simulations. Our waveguide grating design was based on tantala and
fused silica and included a ~20nm thin etch stop layer made of Al2O3 that
allowed us to define the grating depth accurately during the fabrication
process. Demonstrating stable operation of a waveguide grating featuring high
reflectivity in a suspended low-noise cavity, our work paves the way for the
potential application of waveguide gratings as mirrors in high-precision
interferometry, for instance in future gravitational wave observatories
Michelson interferometer with diffractively-coupled arm resonators in second-order Littrow configuration
Michelson-type laser-interferometric gravitational-wave (GW) observatories
employ very high light powers as well as transmissively- coupled Fabry-Perot
arm resonators in order to realize high measurement sensitivities. Due to the
absorption in the transmissive optics, high powers lead to thermal lensing and
hence to thermal distortions of the laser beam profile, which sets a limit on
the maximal light power employable in GW observatories. Here, we propose and
realize a Michelson-type laser interferometer with arm resonators whose
coupling components are all-reflective second-order Littrow gratings. In
principle such gratings allow high finesse values of the resonators but avoid
bulk transmission of the laser light and thus the corresponding thermal beam
distortion. The gratings used have three diffraction orders, which leads to the
creation of a second signal port. We theoretically analyze the signal response
of the proposed topology and show that it is equivalent to a conventional
Michelson-type interferometer. In our proof-of-principle experiment we
generated phase-modulation signals inside the arm resonators and detected them
simultaneously at the two signal ports. The sum signal was shown to be
equivalent to a single-output-port Michelson interferometer with
transmissively-coupled arm cavities, taking into account optical loss. The
proposed and demonstrated topology is a possible approach for future
all-reflective GW observatory designs
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