scholarly journals Coherent-scattering two-dimensional cooling in levitated cavity optomechanics

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Marko Toroš ◽  
Uroš Delić ◽  
Fagin Hales ◽  
Tania S. Monteiro
Keyword(s):  
Coherent Scattering ◽  
Two Dimensional ◽  
Cavity Optomechanics

scholarly journals Focusing a round coherent beam by spatial filtering the horizontal source

2020 ◽  
Vol 27 (6) ◽  
pp. 1528-1538
Author(s):  
Eric M. Dufresne ◽  
Suresh Narayanan ◽  
Ruben Reininger ◽  
Alec R. Sandy ◽  
Larry Lurio
Keyword(s):  
Speckle Pattern ◽  
Spatial Filtering ◽  
Coherent Scattering ◽  
Correlation Spectroscopy ◽  
Two Dimensional ◽  
Array Detectors ◽  
Optical Layout ◽  
Pixel Array ◽  
Speckle Patterns ◽  
Photon Source

This paper illustrates the use of spatial filtering with a horizontal slit near the source to enlarge the horizontal coherence in an experimental station and produce a diffraction-limited round focus at an insertion device beamline for X-ray photon correlation spectroscopy experiments. Simple expressions are provided to guide the optical layout, and wave propagation simulations confirm their applicability. The two-dimensional focusing performance of Be compound refractive lenses to produce a round diffraction-limited focus at 11 keV capable of generating a high-contrast speckle pattern of an aerogel sample is demonstrated. The coherent scattering patterns have comparable speckle sizes in both horizontal and vertical directions. The focal spot sizes are consistent with hybrid ray-tracing calculations. Producing a two-dimensional focus on the sample can be helpful to resolve speckle patterns with modern pixel array detectors with high visibility. This scheme has now been in use since 2019 for the 8-ID beamline at the Advanced Photon Source, sharing the undulator beam with two separate beamlines, 8-ID-E and 8-ID-I at 7.35 keV, with increased partially coherent flux, reduced horizontal spot sizes on samples, and good speckle contrast.

scholarly journals Coherent Scattering of Ultraviolet Light by Avian Feather Barbs

The Auk ◽  
2003 ◽  
Vol 120 (1) ◽  
pp. 163-170 ◽  
Author(s):  
Richard O. Prum ◽  
Staffan Andersson ◽  
Rodolfo H. Torres
Keyword(s):  
Rayleigh Scattering ◽  
Power Spectra ◽  
Coherent Scattering ◽  
Mie Scattering ◽  
Two Dimensional ◽  
Structural Colors ◽  
Physical Mechanisms ◽  
Spatial Frequencies ◽  
Transmission Electron ◽  
Alternative Hypotheses

Abstract Ultraviolet (UV) structural colors of avian feathers are produced by the spongy medullary keratin of feather barbs, but various physical mechanisms have been hypothesized to produce those colors, including Rayleigh scattering, Mie scattering, and coherent scattering (i.e. constructive interference). We used two-dimensional Fourier analysis of transmission electron micrographs of the medullary keratin of UV-colored feather barbs of the Blue Whistling Thrush (Myiophonus caeruleus) (Turdidae) to test the alternative hypotheses for production of those UV structural hues. The two-dimensional Fourier power spectra of the tissue reveal a ring-like distribution of peak periodicity at intermediate spatial frequencies (∼0.078 nm −1), which documents that Myiophonus medullary keratin is substantially nanostructured and equivalently ordered in all directions. This nanoscale spatial order falsifies a basic assumption of both the Rayleigh scattering and Mie scattering. A predicted reflectance spectrum based on the Fourier power spectra matches hue of the measured reflectance spectra of the feathers (345 nm). These results demonstrate that the Myiophonus medullary keratin is ordered at the appropriately nanoscale to produce the observed UV hues by coherent scattering.

scholarly journals Colour-producing β-keratin nanofibres in blue penguin ( Eudyptula minor ) feathers

2011 ◽  
Vol 7 (4) ◽  
pp. 543-546 ◽  
Author(s):  
Liliana D'Alba ◽  
Vinodkumar Saranathan ◽  
Julia A. Clarke ◽  
Jakob A. Vinther ◽  
Richard O. Prum ◽  
...  
Keyword(s):  
Self Assembly ◽  
Coherent Scattering ◽  
Two Dimensional ◽  
Collagen Fibres ◽  
Separation Processes ◽  
New Class ◽  
X Ray Scattering ◽  
Absorption Of Light ◽  
Physical Interactions ◽  
Living Organisms

The colours of living organisms are produced by the differential absorption of light by pigments (e.g. carotenoids, melanins) and/or by the physical interactions of light with biological nanostructures, referred to as structural colours. Only two fundamental morphologies of non-iridescent nanostructures are known in feathers, and recent work has proposed that they self-assemble by intracellular phase separation processes. Here, we report a new biophotonic nanostructure in the non-iridescent blue feather barbs of blue penguins ( Eudyptula minor ) composed of parallel β-keratin nanofibres organized into densely packed bundles. Synchrotron small angle X-ray scattering and two-dimensional Fourier analysis of electron micrographs of the barb nanostructure revealed short-range order in the organization of fibres at the appropriate size scale needed to produce the observed colour by coherent scattering. These two-dimensional quasi-ordered penguin nanostructures are convergent with similar arrays of parallel collagen fibres in avian and mammalian skin, but constitute a novel morphology for feathers. The identification of a new class of β-keratin nanostructures adds significantly to the known mechanisms of colour production in birds and suggests additional complexity in their self-assembly.

scholarly journals Deformable two-dimensional photonic crystal slab for cavity optomechanics

2011 ◽  
Vol 36 (17) ◽  
pp. 3434 ◽  
Author(s):  
Thomas Antoni ◽  
Aurélien G. Kuhn ◽  
Tristan Briant ◽  
Pierre-François Cohadon ◽  
Antoine Heidmann ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Two Dimensional ◽  
Cavity Optomechanics ◽  
Dimensional Photonic Crystal ◽  
Photonic Crystal Slab ◽  
Two Dimensional Photonic Crystal

scholarly journals Coherent light scattering by nanostructured collagen arrays in the caruncles of the malagasy asities (Eurylaimidae: aves)

1999 ◽  
Vol 202 (24) ◽  
pp. 3507-3522 ◽  
Author(s):  
R.O. Prum ◽  
R. Torres ◽  
C. Kovach ◽  
S. Williamson ◽  
S.M. Goodman
Keyword(s):  
Power Spectra ◽  
Coherent Scattering ◽  
Reflectance Spectra ◽  
Two Dimensional ◽  
Collagen Fibres ◽  
Discrete Fourier Analysis ◽  
Near Ultraviolet ◽  
Avian Communication ◽  
Dark Blue ◽  
Prominent Peak

We investigated the anatomy, nanostructure and biophysics of the structurally coloured facial caruncles of three species in a clade of birds endemic to Madagascar (Philepittinae, Eurylaimidae: Aves). Caruncle tissues of all species had reflectance spectra with prominent, peak hues between 403 and 528 nm. Dark blue Neodrepanis tissues had substantial reflectance in the near ultraviolet (320–400 nm), which is visible to birds but not to humans, providing the first evidence of ultraviolet skin colours in birds and the first indications of the possible function of ultraviolet skin colours in avian communication. These structural colours are produced by coherent scattering from arrays of parallel collagen fibres in the dermis. Tissues of Philepitta castanea were organized into hexagonal, crystal-like arrays, whereas Neodrepanis tissues were quasiordered. Predictions of the peak hues of reflectance (λ (max)) using Bragg's law were relatively accurate, but Bragg's law requires physical assumptions that are obviously violated by these structures. A two-dimensional discrete Fourier analysis of the spatial variation in refractive index within the tissues documented that all the tissues are substantially nanostructured at the appropriate spatial scale to scatter visible light coherently. Predicted reflectance spectra based on the two-dimensional Fourier power spectra are relatively accurate at predicting the hue and shape of the reflectance spectra of the tissues. These results confirm that the nanostructure of the collagen arrays determines the colours that are coherently scattered by these tissues. The evolution of the anatomy and nanostructure of asity caruncles is discussed.

Spectrophotometric measurements of objective-prism spectra

1966 ◽  
Vol 24 ◽  
pp. 118-119
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
Progress Report ◽  
Two Dimensional ◽  
Objective Prism ◽  
Made In

I should like to give you a very condensed progress report on some spectrophotometric measurements of objective-prism spectra made in collaboration with H. Leicher at Bonn. The procedure used is almost completely automatic. The measurements are made with the help of a semi-automatic fully digitized registering microphotometer constructed by Hög-Hamburg. The reductions are carried out with the aid of a number of interconnected programmes written for the computer IBM 7090, beginning with the output of the photometer in the form of punched cards and ending with the printing-out of the final two-dimensional classifications.

Introductory paper

1966 ◽  
Vol 24 ◽  
pp. 3-5
Author(s):  
W. W. Morgan
Keyword(s):  
Line Intensity ◽  
Classification Scheme ◽  
Two Dimensional ◽  
Spectral Classification ◽  
Dimensional Array ◽  
Rr Lyrae ◽  
Metallic Line ◽  
Introductory Paper ◽  
Parameter Varying ◽  
Definition Of

1. The definition of “normal” stars in spectral classification changes with time; at the time of the publication of theYerkes Spectral Atlasthe term “normal” was applied to stars whose spectra could be fitted smoothly into a two-dimensional array. Thus, at that time, weak-lined spectra (RR Lyrae and HD 140283) would have been considered peculiar. At the present time we would tend to classify such spectra as “normal”—in a more complicated classification scheme which would have a parameter varying with metallic-line intensity within a specific spectral subdivision.

Sign in / Sign up

Export Citation Format

Share Document