Image resolution analysis of atmospheric turbulence on the high-resolution space optical systems

2015 ◽  
Author(s):  
Lili Jiang ◽  
Xiaomei Chen ◽  
Guoqiang Ni
Keyword(s):  
High Resolution ◽  
Atmospheric Turbulence ◽  
Image Resolution ◽  
Optical Systems ◽  
Resolution Analysis ◽  
Space Optical Systems

scholarly journals Adaptive selective relaying in cooperative free-space optical systems over atmospheric turbulence and misalignment fading channels

2014 ◽  
Vol 22 (13) ◽  
pp. 16629 ◽  
Author(s):  
Rubén Boluda-Ruiz ◽  
Antonio García-Zambrana ◽  
Carmen Castillo-Vázquez ◽  
Beatriz Castillo-Vázquez
Keyword(s):  
Fading Channels ◽  
Atmospheric Turbulence ◽  
Free Space ◽  
Optical Systems ◽  
Free Space Optical ◽  
Space Optical Systems

scholarly journals A Single Motor-Driven Focusing Mechanism with Flexure Hinges for Small Satellite Optical Systems

2020 ◽  
Vol 10 (20) ◽  
pp. 7087
Author(s):  
Jinwon Jung ◽  
Nguyen Van Sy ◽  
Dongkyu Lee ◽  
Seonggun Joe ◽  
Jaihyuk Hwang ◽  
...  
Keyword(s):  
High Resolution ◽  
Optical System ◽  
High Vacuum ◽  
Longitudinal Direction ◽  
Image Resolution ◽  
Optical Systems ◽  
Modulation Transfer ◽  
Small Satellites ◽  
Single Motor ◽  
Flexure Hinges

For earth observation, the optical systems in small satellites are crucial to obtain high- resolution images. However, the alignment between a primary and a secondary mirror in an optical system can be disturbed due to the harsh environments inside vehicles or space (i.e., vibrations, shock loading during launch, dramatic temperature changes, or high vacuum pressure in space). To compensate for such undesired deformations, a focusing mechanism should be embedded into the optical system. In this paper, we propose a novel Single Motor-Driven Focusing mechanism with Flexure Hinges (SMFH), allowing the Flexure Hinge (FlexHe) to displace in the longitudinal direction. The presented FlexHe incorporates radial zig-zag-patterned slits to achieve flexibility, and preloading of the hinge structures to reduce the resulting hysteresis. To investigate an optimal configuration of FlexHe, a numerical simulation is performed by means of ANSYS 19.2. The variation of Modulation Transfer Function (MTF), corresponding to an image resolution, is evaluated by using an optics simulation program (CODE-V). The experimental setups are built by exploiting the fabricated SMFH and five LVDT (Linear Variable Differential Transformer) sensors with a high resolution of 0.031 µm. As a result, hysteresis can be reduced up to 6.52% with a pre-stretched length of 3 µm. The proposed SMFH allows not only the De-space to displace up to 23.93 µm, but also the De-center and the Tilt to achieve the desired displacements of 5.20 µm and 88.45 µrad, respectively. Conclusively, the SMFH shows promising characteristics to embed a feedback control, due to its high resolution (up to 0.1 µm) for De-space with the MTF of 37%.

Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid

1994 ◽  
Vol 144 ◽  
pp. 593-596
Author(s):  
O. Bouchard ◽  
S. Koutchmy ◽  
L. November ◽  
J.-C. Vial ◽  
J. B. Zirker
Keyword(s):  
High Resolution ◽  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Field Of View ◽  
Small Field ◽  
High Resolution Analysis ◽  
Ccd Observations ◽  
Resolution Analysis ◽  
Very High ◽  
Small Field Of View

AbstractWe present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5“, a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse.

Towards 1-Ångstrom-resolution STEM

1993 ◽  
Vol 51 ◽  
pp. 996-997
Author(s):  
H.S. von Harrach ◽  
D.E. Jesson ◽  
S.J. Pennycook
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Phase Contrast ◽  
Spherical Aberration ◽  
A Priori ◽  
Dark Field ◽  
Image Resolution ◽  
Objective Lens ◽  
Annular Dark Field ◽  
First Results

Phase contrast TEM has been the leading technique for high resolution imaging of materials for many years, whilst STEM has been the principal method for high-resolution microanalysis. However, it was demonstrated many years ago that low angle dark-field STEM imaging is a priori capable of almost 50% higher point resolution than coherent bright-field imaging (i.e. phase contrast TEM or STEM). This advantage was not exploited until Pennycook developed the high-angle annular dark-field (ADF) technique which can provide an incoherent image showing both high image resolution and atomic number contrast.This paper describes the design and first results of a 300kV field-emission STEM (VG Microscopes HB603U) which has improved ADF STEM image resolution towards the 1 angstrom target. The instrument uses a cold field-emission gun, generating a 300 kV beam of up to 1 μA from an 11-stage accelerator. The beam is focussed on to the specimen by two condensers and a condenser-objective lens with a spherical aberration coefficient of 1.0 mm.

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