Micro-optical structure for wave aberration compensation of optical systems

2005 ◽  
Author(s):  
Chunlei Du ◽  
Xiaochun Dong ◽  
Chuankai Qiu ◽  
Hongtao Gao ◽  
Xuejun Rao ◽  
...  
Keyword(s):  
Optical Systems ◽  
Wave Aberration ◽  
Optical Structure

Decomposition of the total wave aberration in generalized optical systems

2017 ◽  
Vol 34 (10) ◽  
pp. 1856 ◽  
Author(s):  
Mateusz Oleszko ◽  
Ralf Hambach ◽  
Herbert Gross
Keyword(s):  
Optical Systems ◽  
Total Wave ◽  
Wave Aberration

scholarly journals Active optics with silk

Nanophotonics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 137-148 ◽  
Author(s):  
Giulia Guidetti ◽  
Yu Wang ◽  
Fiorenzo G. Omenetto
Keyword(s):  
Optical Response ◽  
Optical Systems ◽  
Research Directions ◽  
Active Optics ◽  
Optical Responses ◽  
Design Changes ◽  
Regenerated Silk Fibroin ◽  
New Research ◽  
Intrinsic Dynamic ◽  
Optical Structure

AbstractOptical devices have been traditionally fabricated using materials whose chemical and physical properties are finely tuned to perform a specific, single, and often static function, whereby devices’ variability is achieved by design changes. Due to the integration of optical systems in multifunctional platforms, there is an increasing need for intrinsic dynamic behavior, such as devices built with materials whose optical response can be programmed to change by leveraging the material’s variability. Here, regenerated silk fibroin is presented as an enabler of devices with active optical response due to the protein’s intrinsic properties. Silk’s abilities to controllably change conformation, reversibly swell and shrink, and degrade in a programmable way affect the form and the response of the optical structure in which it is molded. Representative silk-based devices whose behavior depends on the silk variability are presented and discussed with a particular focus on structures that display reconfigurable, reversibly tunable and physically transient optical responses. Finally, new research directions are envisioned for silk-based optical materials and devices.

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.

Electron Holography Improving Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 208-209
Author(s):  
Hannes Lichte
Keyword(s):  
Electron Microscopy ◽  
Transfer Functions ◽  
Imaging System ◽  
Spherical Aberration ◽  
Image Plane ◽  
Chromatic Aberration ◽  
Object Wave ◽  
Objective Lens ◽  
Electron Holography ◽  
Wave Aberration

Generally, the electron object wave o(r) is modulated both in amplitude and phase. In the image plane of an ideal imaging system we would expect to find an image wave b(r) that is modulated in exactly the same way, i. e. b(r) =o(r). If, however, there are aberrations, the image wave instead reads as b(r) =o(r) * FT(WTF) i. e. the convolution of the object wave with the Fourier transform of the wave transfer function WTF . Taking into account chromatic aberration, illumination divergence and the wave aberration of the objective lens, one finds WTF(R) = Echrom(R)Ediv(R).exp(iX(R)) . The envelope functions Echrom(R) and Ediv(R) damp the image wave, whereas the effect of the wave aberration X(R) is to disorder amplitude and phase according to real and imaginary part of exp(iX(R)) , as is schematically sketched in fig. 1.Since in ordinary electron microscopy only the amplitude of the image wave can be recorded by the intensity of the image, the wave aberration has to be chosen such that the object component of interest (phase or amplitude) is directed into the image amplitude. Using an aberration free objective lens, for X=0 one sees the object amplitude, for X= π/2 (“Zernike phase contrast”) the object phase. For a real objective lens, however, the wave aberration is given by X(R) = 2π (.25 Csλ3R4 + 0.5ΔzλR2), Cs meaning the coefficient of spherical aberration and Δz defocusing. Consequently, the transfer functions sin X(R) and cos(X(R)) strongly depend on R such that amplitude and phase of the image wave represent only fragments of the object which, fortunately, supplement each other. However, recording only the amplitude gives rise to the fundamental problems, restricting resolution and interpretability of ordinary electron images:

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