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%.

Comparison of Design and Spatial Stability of Two Kinds of Optical Systems for Stereoscopic Mapping Camera

2013 ◽  
Vol 760-762 ◽  
pp. 368-372
Author(s):  
Tian Jin Tang ◽  
Wei Jun Gao
Keyword(s):  
Optical System ◽  
Linear Array ◽  
Focal Length ◽  
Optical Systems ◽  
Modulation Transfer ◽  
Working Temperature ◽  
Edge Field ◽  
Performance Requirements ◽  
And Performance ◽  
Structure Layout

To achieve a certain precision when mapping in accord with a particular proportion or scale with stereo mapping camera, the change of chief ray height of the edge field due to the fluctuation of working temperature is required to be within the range of microns, and at the meantime the size and structure layout of three-linear array stereo mapping camera are determined directly by the configuration of optical system. Based on the requirements of refractive optical system with long focal length, academic calculation and actual optical designs based on two typical configurations for stereoscopic mapping camera are made,the actual working temperature and performance requirements are also taken into consideration, the results including the modulation transfer function, distortion and stability comparison are also given.

Design of Athermalized Infrared Telephoto Lens

2013 ◽  
Vol 552 ◽  
pp. 8-13
Author(s):  
Yu Zhang ◽  
Ji Yang Shang ◽  
Yue Xu ◽  
Wen Sheng Wang
Keyword(s):  
Image Quality ◽  
Optical System ◽  
Power Distribution ◽  
Focal Length ◽  
Diffraction Limit ◽  
Field Of View ◽  
Optical Systems ◽  
Modulation Transfer ◽  
Full Field ◽  
Telephoto Lens

IR optical system is much more appropriate to be applied in cluttered and formidable conditions. The change of temperature could degrade image quality of the infrared optical system. So the athermalization becomes the difficult part and key factor in the designing of MWIR optical systems for working under temperature range of -40°C~60°C. In this paper, the infrared telephoto lens is designed; it meets the designing requirements and has good image quality. The effective focal length is 240mm and the F-number is 2.The full field of view is 3.2°. In order to balance the chromatic aberration, an aspherical surface is used in the athermalized infrared optical system. Through carefully selected optical material and reasonable optical power distribution, passive optical athermalization can be realized. The curve of MTF is close to diffraction limit. Within the working temperature, the value of MTF at 30cy/mm is always large than 0.6. The results show that the modulation transfer function (MTF) of optical system in all field of view approaches the diffraction limit at different temperature, and 80% energy concentrates in 1 pixel.

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

A Field Emission System For Transmission Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 298-299
Author(s):  
Michel Troyonal ◽  
Huei Pei Kuoal ◽  
Benjamin M. Siegelal
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Optical System ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Objective Lens ◽  
Electron Optical System ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Emission System

A field emission system for our experimental ultra high vacuum electron microscope has been designed, constructed and tested. The electron optical system is based on the prototype whose performance has already been reported. A cross-sectional schematic illustrating the field emission source, preaccelerator lens and accelerator is given in Fig. 1. This field emission system is designed to be used with an electron microscope operated at 100-150kV in the conventional transmission mode. The electron optical system used to control the imaging of the field emission beam on the specimen consists of a weak condenser lens and the pre-field of a strong objective lens. The pre-accelerator lens is an einzel lens and is operated together with the accelerator in the constant angular magnification mode (CAM).

A Base Specific Single Heavy Atom Stain for Electron Microscopy

1972 ◽  
Vol 30 ◽  
pp. 184-185
Author(s):  
J. P. Langmore ◽  
N. R. Cozzarelli ◽  
A. V. Crewe
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
Elastic Scattering ◽  
Heavy Atom ◽  
High Vacuum ◽  
Heavy Atoms ◽  
Large Movement ◽  
Base Sequencing ◽  
Scanning Electron

A system has been developed to allow highly specific derivatization of the thymine bases of DNA with mercurial compounds wich should be visible in the high resolution scanning electron microscope. Three problems must be completely solved before this staining system will be useful for base sequencing by electron microscopy: 1) the staining must be shown to be highly specific for one base, 2) the stained DNA must remain intact in a high vacuum on a thin support film suitable for microscopy, 3) the arrangement of heavy atoms on the DNA must be determined by the elastic scattering of electrons in the microscope without loss or large movement of heavy atoms.

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.

Atomic Resolution in Crystal Aperture Stem

1990 ◽  
Vol 48 (1) ◽  
pp. 236-237
Author(s):  
J T Fourie
Keyword(s):  
Optical System ◽  
Spherical Aberration ◽  
Three Dimensional ◽  
Transmission Function ◽  
Optical Systems ◽  
Bragg Angle ◽  
Electron Optical System ◽  
Intimate Contact ◽  
Diffraction Effects ◽  
Design Aspect

The attempts at improvement of electron optical systems to date, have largely been directed towards the design aspect of magnetic lenses and towards the establishment of ideal lens combinations. In the present work the emphasis has been placed on the utilization of a unique three-dimensional crystal objective aperture within a standard electron optical system with the aim to reduce the spherical aberration without introducing diffraction effects. A brief summary of this work together with a description of results obtained recently, will be given.The concept of utilizing a crystal as aperture in an electron optical system was introduced by Fourie who employed a {111} crystal foil as a collector aperture, by mounting the sample directly on top of the foil and in intimate contact with the foil. In the present work the sample was mounted on the bottom of the foil so that the crystal would function as an objective or probe forming aperture. The transmission function of such a crystal aperture depends on the thickness, t, and the orientation of the foil. The expression for calculating the transmission function was derived by Hashimoto, Howie and Whelan on the basis of the electron equivalent of the Borrmann anomalous absorption effect in crystals. In Fig. 1 the functions for a g220 diffraction vector and t = 0.53 and 1.0 μm are shown. Here n= Θ‒ΘB, where Θ is the angle between the incident ray and the (hkl) planes, and ΘB is the Bragg angle.

scholarly journals Set-up of a high-resolution 300 mK atomic force microscope in an ultra-high vacuum compatible 3He/10 T cryostat

2016 ◽  
Vol 87 (7) ◽  
pp. 073702 ◽  
Author(s):  
H. von Allwörden ◽  
K. Ruschmeier ◽  
A. Köhler ◽  
T. Eelbo ◽  
A. Schwarz ◽  
...  
Keyword(s):  
High Resolution ◽  
Atomic Force Microscope ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Atomic Force ◽  
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