نتایج جستجو برای: minimum aberration

تعداد نتایج: 172536  

2000
Edward R. Dowski Joseph van der Gracht

By optimum combination of optical pre-processing and digital post-processing, or optical coding and digital decoding of the image information, incoherent optical systems invariant to numerous aberrations can be formed. The theory of aberration invariance can also be used with low-cost, low-precision optics to produce systems that image with the performance of high-cost, high-precision, or near ...

Journal: :Journal of the Optical Society of America. A, Optics and image science 1988
P Artal J Santamaría J Bescós

The wave aberration of human eyes is retrieved from actual point-spread-function (PSF) data and the modulus of the pupil function. The PSF had been obtained previously by application of a hybrid optical-digital method developed recently. The retrieval is done by using a bidimensional Gerchberg-Saxton phase-retrieval algorithm joined to an iterative phase-unwrapping algorithm. To obtain an adequ...

Journal: :iranian journal of radiation research 0
h. samavat dept. of medical physics, hamedan university of medical sciences, hamedan, iran m. r. d. seaward d. h. gonzales gh. azizian

background: most of our current understanding of the biological effects of exposure to ionising radiation is based on conventional cytogenetic techniques, which enable us to determine the relationship between chromosomal aberration and dose received by radiation workers. however, conventional techniques have numerous limitations and chromosomal aberrations can be easily missed. since fish plays...

2007
A I Kirkland

Aberration correction in the TEM is now relatively well established with more than 20 corrected instruments installed worldwide. This paper will review these instrumental advances and will also describe the underlying theory and computation required to optimise data acquisition and interpret aberration corrected images. Finally the combination of direct electron optical correction and indirect ...

Journal: :Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada 2012
Andrew R Lupini Stephen J Pennycook

The resolution of conventional electron microscopes is usually limited by spherical aberration. Microscopes equipped with aberration correctors are then primarily limited by higher order, chromatic, and misalignment aberrations. In particular the Nion third-order aberration correctors installed on machines with a low energy spread and possessing sophisticated alignment software were limited by ...

2012
P Wang

Scanning confocal electron microscopy (SCEM) is a new imaging mode in electron microscopy. Spherical aberration corrected electron microscope instruments fitted with two aberration correctors can be used in this mode which provides improved depth resolution and selectivity compared to optical sectioning in a conventional scanning transmission geometry. In this article, we consider the depth res...

Journal: :Journal of the Optical Society of America. A, Optics, image science, and vision 2006
George Smith David A Atchison Sergio Barbero

We derive equations for defocus and primary spherical wave aberration coefficients caused by a shift in image plane of a perfect optical system. The spherical aberration equation is accurate at describing changes in the spherical aberration of an aberrated schematic eye.

2014
Yun Zhang Xueming Li Jianli Zhang Derui Song

and Applied Analysis 3 operator, the chromatic aberration Canny operator was used instead to extract the coastline. (1) Calculation of the Chromatic Aberration Amplitude by Means of Chromatic Aberration Canny Operator. In order to improve on deficiencies of the traditional Canny operator, an improved Canny operator was used based on the LAB color model as the main technical route in this paper,...

Journal: :Vision Research 1996
RUSSELL L WOODS ARTHUR BRADLEY DAVID A ATCHISON

As a single aperture, approximately monofocal optical system, the human eye generally creates a single image on the retina. However, the literature contains many reports of perceptual monocular diplopia. While it is easy to understand how distortion may produce monocular diplopia, its reported high incidence in normal eyes is less easily understood. We examine a model which ascribes monocular d...

Journal: :Vision Research 2005
Howard C. Howland

The scaling of root mean square (RMS) wave aberration in an isometrically growing eye is investigated, along with changes due to measurements made at different relative pupil sizes. It is found that, relative to an initial state, if an eye expands in all directions by the factor k, and the wave aberration is then measured at a relative pupil size which has changed over the pupil size used for t...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید