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Category :
Languages : en
Pages :
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Abstract : We studied the effect of image enhancement techniques on digital holograms based on an in-line holographic system for air-borne cloud droplet measurements. A super-Gaussian filter is applied to pre-process the padded raw hologram prior to the reconstruction. The size distribution of pre-processed hologram with padding and filtering depicts a shift to the larger diameter of cloud particles due to the dilation of detected particle images. The dilated particles reside within the instrument's detectable size range. Two different padding methods: (1) zero padding and (2) mean padding show almost identical consequence for number concentration and particle size dilation. However, the pre-processed hologram with padding alone results in minimal improvement.
Author: Lifan Hua
Publisher:
ISBN:
Category :
Languages : en
Pages : 358
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Author:
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Category : Holography
Languages : en
Pages : 410
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The work embodied in this thesis describes software techniques developed to analyse digital inline holograms of suspended particle fields, particularly in aquatic environ- ments. The primary motivation behind this work has been development of tech- niques to extract useable information from individual holograms within holovideos, producing focused silhouettes of recorded plankton and other particulates with min- imal user intervention. Two automated focusing algorithms are developed and presented in this work, both of which obtain comparable results for holograms of sparse plankton populations. The first approach is based on rectangular regions of interest (ROIs), which are aligned to (x, y) dimensions, and localise particles within the two-dimensional recon- structed planes obtained from holovideo frames. Due to poor immunity to particle merging when applied to denser particle fields, a second approach was developed using arbitrary polygons with which to localise particle positions in reconstructed planes. This new approach offers a greater immunity to the merging of particles lying in close proximity in the (x, y) dimensions of the hologram, and allows better particle localisation for high density particle holograms. Both ROI and polygon based particle localisation are explored to identify strengths and weaknesses, and complete automated scanning procedures developed in both cases. Examples are provided of typical output from automated scanning algorithms when applied to a number of sample holograms, and areas of weakness highlighted for future work.
Author: Myung K. Kim
Publisher: Springer
ISBN: 1441977937
Category : Science
Languages : en
Pages : 251
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Book Description
Digital holography is an emerging field of new paradigm in general imaging applications. The book presents an introduction to the theoretical and numerical principles and reviews the research and development activities in digital holography, with emphasis on the microscopy techniques and applications. Topics covered include the general theory of diffraction and holography formations, and practical instrumentation and experimentation of digital holography. Various numerical techniques are described that give rise to the unique and versatile capabilities of digital holography. Representative special techniques and applications of digital holography are discussed. The book is intended for researchers interested in developing new techniques and exploring new applications of digital holography.
Author:
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Category : Aeronautics
Languages : en
Pages : 324
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Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 940
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Author: Geoff Dougherty
Publisher: Cambridge University Press
ISBN: 0521860857
Category : Computers
Languages : en
Pages : 463
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Book Description
Hands-on text for a first course aimed at end-users, focusing on concepts, practical issues and problem solving.
Author: Ronald J. Adrian
Publisher: Cambridge University Press
ISBN: 0521440084
Category : Science
Languages : en
Pages : 585
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Book Description
Particle image velocimetry, or PIV, refers to a class of methods used in experimental fluid mechanics to determine instantaneous fields of the vector velocity by measuring the displacements of numerous fine particles that accurately follow the motion of the fluid. Although the concept of measuring particle displacements is simple in essence, the factors that need to be addressed to design and implement PIV systems that achieve reliable, accurate, and fast measurements and to interpret the results are surprisingly numerous. The aim of this book is to analyze and explain them comprehensively.
Author: Zi-Lan Deng
Publisher: Springer Nature
ISBN: 3031023862
Category : Science
Languages : en
Pages : 68
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Book Description
The merging of metasurface and holography brings about unprecedented opportunities for versatile manipulation of light in terms of both far-field wavefront and near-field profile. In this book, a brief evolving history from surface plasmon polariton holography to metamaterial holography and finally to metasurface holography is introduced at first. Basic physical mechanisms that govern the phase modulation rules behind metasurface holography design are discussed later. Next, extended functionalities such as arbitrary polarization holography, vectorial holography, full-color holography, and hybrid holography achieved in the metasurface platform are presented. Surface wave and metagrating holography that bridges the on-chip surface wave and free-space wave is also introduced. In the end, we envisage practical applications of high-fidelity 3D holographic display, high-secure encryption, and high capacity digital encoding and also indicate remaining challenges based on metasurface holography.
Author: Izabela Naydenova
Publisher: BoD – Books on Demand
ISBN: 9533077298
Category : Technology & Engineering
Languages : en
Pages : 392
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Book Description
Advanced Holography - Metrology and Imaging covers digital holographic microscopy and interferometry, including interferometry in the infra red. Other topics include synthetic imaging, the use of reflective spatial light modulators for writing dynamic holograms and image display using holographic screens. Holography is discussed as a vehicle for artistic expression and the use of software for the acquisition of skills in optics and holography is also presented. Each chapter provides a comprehensive introduction to a specific topic, with a survey of developments to date.
