Shape transition between symmetric and asymmetric structures in epitaxial three-dimensional strained islands

2008 ◽  
Vol 92 (3) ◽  
pp. 031905 ◽  
Author(s):  
Y. C. Chu ◽  
C. J. Tsai
Keyword(s):  
Three Dimensional ◽  
Shape Transition ◽  
Asymmetric Structures

scholarly journals Imaging the disc rim and a moving close-in companion candidate in the pre-transitional disc of V1247 Orionis

2018 ◽  
Vol 621 ◽  
pp. A7 ◽  
Author(s):  
Matthew Willson ◽  
Stefan Kraus ◽  
Jacques Kluska ◽  
John D. Monnier ◽  
Michel Cure ◽  
...  
Keyword(s):  
Dust Emission ◽  
Three Dimensional ◽  
Position Angle ◽  
Asymmetric Structures ◽  
North East ◽  
The North ◽  
Band Emission ◽  
Upper Limits ◽  
Multi Wavelength ◽  
Differential Imaging

Context. V1247 Orionis harbours a pre-transitional disc with a partially cleared gap. Earlier interferometric and polarimetric observations revealed strong asymmetries both in the gap region and in the outer disc. The presence of a companion was inferred to explain these asymmetric structures and the ongoing disc clearing. Aims. Using an extensive set of multi-wavelength and multi-epoch observations we aimed to identify the origin of the previously detected asymmetries. Methods. We have observed V1247 Ori at three epochs spanning ~678 days using sparse aperture masking interferometry with Keck/NIRC2 and VLT/NACO. In addition, we search for signs of accretion through VLT/SPHERE-ZIMPOL spectral differential imaging in Hα and R-band continuum. Our SMA sub-millimetre interferometry in 880 μm continuum and in the CO(3-2) line allows us to constrain the orientation and direction of rotation of the outer disc. Results. We find the L′-band emission to be dominated by static features which trace forward-scattered dust emission from the inner edge of the outer disc located to the north-east. In H- and K-bands, we see evidence for a companion candidate that moved systematically by 45° within the first ~345 days. The separation of the companion candidate is not well constrained, but the observed position angle change is consistent with Keplerian motion of a body located on a 6 au orbit. From the SMA CO moment map, the location of the disc rim, and the detected orbital motion, we deduced the three-dimensional orientation of the disc. We see no indication of accretion in Hα and set upper limits for an accreting companion. Conclusions. The measured contrast of the companion candidate in H and K is consistent with an actively accreting protoplanet. Hence, we identify V1247 Ori as a unique laboratory for studying companion–disc interactions and disc clearing.

scholarly journals Influence of Illumination Polarization and Target Structure on Measurement Sensitivity of Through-Focus Scanning Optical Microscopy

2018 ◽  
Vol 8 (10) ◽  
pp. 1819 ◽  
Author(s):  
Yufu Qu ◽  
Renju Peng ◽  
Jialin Hao ◽  
Hui Pan ◽  
Jiebin Niu ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Three Dimensional ◽  
Polarized Light ◽  
Target Structure ◽  
Measurement Sensitivity ◽  
Dimensional Inspection ◽  
Asymmetric Structures ◽  
Enhanced Sensitivity ◽  
Focus Image ◽  
Scanning Optical Microscopy

Unlike the optical information taken from a single in-focus image of general optical microscopy, through-focus scanning optical microscopy (TSOM) involves scanning a target through the focus and capturing of a series of images. These images can be used to conduct three-dimensional inspection and metrology with nanometer-scale lateral and vertical sensitivity. The sensitivity of TSOM strongly depends on many mechanical and optical factors. In this study, how illumination polarization and target structure affect the sensitivity of TSOM is analyzed. Firstly, the complete imaging procedure of the polarized light is investigated. Secondly, through-focus scanning results of different targets with two illumination polarizations are simulated using the finite-difference time-domain method. Thirdly, a few experiments are performed to verify the influence of illumination polarization and target structures on the sensitivity of TSOM. Both the results of the simulation and experiments illustrate an apparent influence of polarization on the sensitivity of inspecting the targets with center asymmetric structures. For enhanced sensitivity, illumination polarization should be perpendicular to the target texture. This conclusion is meaningful to adjust illumination polarization purposefully for different structure characteristics and improve the sensitivity of metrology.

scholarly journals Shape transition of coherent three-dimensional (In,Ga)As islands on GaAs(100)

2001 ◽  
Vol 79 (25) ◽  
pp. 4219-4221 ◽  
Author(s):  
Wenquan Ma ◽  
Richard Nötzel ◽  
Hans-Peter Schönherr ◽  
Klaus H. Ploog
Keyword(s):  
Three Dimensional ◽  
Shape Transition

The Extended Adaptive Capacity Spectrum Method for the Seismic Assessment of Plan-Asymmetric Buildings

2014 ◽  
Vol 30 (2) ◽  
pp. 683-703 ◽  
Author(s):  
Carlos Bhatt ◽  
Rita Bento
Keyword(s):  
Adaptive Capacity ◽  
Three Dimensional ◽  
Seismic Assessment ◽  
Capacity Spectrum Method ◽  
Existing Structures ◽  
Asymmetric Structures ◽  
Asymmetric Buildings ◽  
Spectrum Method ◽  
Capacity Spectrum ◽  
N2 Method

The use of nonlinear static procedures (NSPs) on the seismic assessment of real existing plan-irregular structures has so far been studied by a limited number of authors. This fact limits the application of such methods to assess current existing structures, the majority of which are irregular in plan. An extended version of the adaptive capacity spectrum method (ACSM) for the seismic assessment of plan-irregular buildings is presented in this paper. The novelty of this proposal is to comprise the most accurate features of commonly used NSPs in order to overcome the problems that subsist in three-dimensional pushover analyses. The accuracy of the procedure is tested in three plan-irregular real buildings. The results are compared with the capacity spectrum method (CSM) with the features proposed in FEMA 440, with the extended N2 method for plan-asymmetric structures, with the adaptive capacity spectrum method (ACSM) and with the most exact nonlinear dynamic analyses. Several seismic intensities are tested, in order to evaluate the performance of the procedure in different stages of structural inelasticity.

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