Chapter Optical Coherence Tomography – Applications in Non- Destructive Testing and Evaluation

Optimizatio

3D printing and inspection

Non-destructive dimensional inspection of surfaces is an issue of utmost importance in a large number of situations in R&D and at the industrial world. An increasing number of surfaces and sur-face types must be microtopographically characterized in a non-destructive non-invasive way [1]. Statistical parameters, both 2D and 3D, are fundamental to a useful quantitative characterization of the surface’ relief. However the two and tridimensional magnified representation of the microtopo-graphic structure of the surface, allowing a comfortable and detailed visualization of the relief structure, gives very meaningful insights and is more and more requested.info:eu-repo/semantics/publishedVersio

Physical Modeling of Full-Field Time-Domain Optical Coherence Tomography

In this paper, a physical model of full-field time-domain optical coherence tomography (FF-TD OCT), which focuses the requirements of measuring inner textures of flexible layered samples in industrial applications, is developed and validated by reference measurements. Both the operating principle and the overall design of a FF-TD OCT correspond to that of classical white light interferometry (WLI), commonly used for the measurement of areal micro-topographies. The presented model accounts for optical and geometrical properties of the system, multiple scattering of light in turbid media and interference of partially coherent light. Applying this model, virtual measurements are used to exemplarily investigate the extent to which the principles of classical WLI can be directly transferred to obtain layer thickness measurements by simulating the use of a simple low-cost WLI system as OCT. Results indicate that a currently existing instrument setup can only be used as OCT to a very limited extent but not in general due to its initial design as a WLI

Optical Coherence Tomography and Its Non-medical Applications

Optical coherence tomography (OCT) is a promising non-invasive non-contact 3D imaging technique that can be used to evaluate and inspect material surfaces, multilayer polymer films, fiber coils, and coatings. OCT can be used for the examination of cultural heritage objects and 3D imaging of microstructures. With subsurface 3D fingerprint imaging capability, OCT could be a valuable tool for enhancing security in biometric applications. OCT can also be used for the evaluation of fastener flushness for improving aerodynamic performance of high-speed aircraft. More and more OCT non-medical applications are emerging. In this book, we present some recent advancements in OCT technology and non-medical applications

Fast and cost-effective in-process defect inspection for printed electronics based on coherent optical processing

This paper presents an all-optical difference engine (AODE) sensor for detecting the defects in printed electronics produced with roll-to-roll processes. The sensor is based on the principle of coherent optical subtraction and is able to achieve high-speed inspection by minimising data post-processing. A self-comparison inspection strategy is introduced to allow defect detection by comparing the printed features and patterns that have the same nominal dimensions. In addition, potential applications of the AODE sensor in an on-the-fly pass-orreject production control scenario are presented. A prototype AODE sensor using a digital camera is developed and demonstrated by detecting defects on several industrial printed electrical circuitry samples. The camera can be easily replaced by a low-cost photodiode to realise high-speed all-optical information processing and inspection. The developed sensor is capable of inspecting areas of 4 mm width with a resolution of the order of several micrometres, and can be duplicated in parallel to inspect larger areas without significant cost

Development and Characterization of a Dispersion-Encoded Method for Low-Coherence Interferometry

This Open Access book discusses an extension to low-coherence interferometry by dispersion-encoding. The approach is theoretically designed and implemented for applications such as surface profilometry, polymeric cross-linking estimation and the determination of thin-film layer thicknesses. During a characterization, it was shown that an axial measurement range of 79.91 µm with an axial resolution of 0.1 nm is achievable. Simultaneously, profiles of up to 1.5 mm in length were obtained in a scan-free manner. This marked a significant improvement in relation to the state-of-the-art in terms of dynamic range. Also, the axial and lateral measurement range were decoupled partially while functional parameters such as surface roughness were estimated. The characterization of the degree of polymeric cross-linking was performed as a function of the refractive index. It was acquired in a spatially-resolved manner with a resolution of 3.36 x 10-5. This was achieved by the development of a novel mathematical analysis approach

Optics and Fluid Dynamics Department annual progress report for 2002

research within three scientific programmes: (1) laser systems and optical materials, (2) optical diagnostics and information processing and (3) plasma and fluid dynamics. The department has core competences in: optical sensors, optical materials, optical storage, biophotonics, numerical modelling and information processing, non-linear dynamics and fusion plasma physics. The research is supported by several EU programmes, including EURATOM, by Danish research councils and by industry. A summary of the activities in 2002 is presented. ISBN 87-550-3197-8 (Internet

Brief overview of the current status of the research in optics and photonics in Portugal

The Portuguese Optics and Photonics Society, SPOF, Sociedade Portuguesa para a Investi-gação e Desenvolvimento em Óptica e Fotónica, [1] was established in November 2009 reflecting the development of the scientific and technological research in Optics and Photonics in Portugal over last decades. Since then the research in optics and photonics both at academic level but also, notably and increasingly, at the industry, is experiencing a remarkable development. In this communication we will proceed with a brief presentation of the main research groups and research lines in Portugal. The very positive experience with the newly established photonics companies and spin-offs is going to be presented as well as SPOF main activities that included the organization of the last edition of RIAO/OPTILAS [2] and the 12th Education and Training in Optics and Photonics Conference and in 2013 [3] and two major AOP conferences in 2011 [4] and 2014 [5]. The next edition of SPOF’ triennial conference AOP2017 will be held at the University of Algarve in Faro, Portugal, May 8 to 12, 2017 [6].info:eu-repo/semantics/draf

Continuous In‐Line Chromium Coating Thickness Measurement Methodologies:An Investigation of Current and Potential Technology

Coatings or films are applied to a substrate for several applications, such as waterproofing, corrosion resistance, adhesion performance, cosmetic effects, and optical coatings. When applying a coating to a substrate, it is vital to monitor the coating thickness during the coating process to achieve a product to the desired specification via real time production control. There are several different coating thickness measurement methods that can be used, either in-line or off-line, which can determine the coating thickness relative to the material of the coating and the substrate. In-line coating thickness measurement methods are often very difficult to design and implement due to the nature of the harsh environmental conditions of typical production processes and the speed at which the process is run. This paper addresses the current and novel coating thickness methodologies for application to chromium coatings on a ferro-magnetic steel substrate with their advantages and limitations regarding in-line measurement. The most common in-line coating thickness measurement method utilized within the steel packaging industry is the X-ray Fluorescence (XRF) method, but these systems can become costly when implemented for a wide packaging product and pose health and safety concerns due to its ionizing radiation. As technology advances, nanometer-scale coatings are becoming more common, and here three methods are highlighted, which have been used extensively in other industries (with several variants in their design) which can potentially measure coatings of nanometer thickness in a production line, precisely, safely, and do so in a non-contact and non-destructive manner. These methods are optical reflectometry, ellipsometry and interferometry

OCT for non-destructive examination of the internal biological structures of mosquito specimen

The Study of mosquitoes and their behavioral analysis are of crucial importance to control the alarmingly increasing mosquito-borne diseases. Conventional imaging techniques use either dissection, exogenous contrast agents. Non-destructive imaging techniques, like x-ray and microcomputed tomography uses ionizing radiations. Hence, a non-destructive and real-time imaging technique which can obtain high resolution images to study the anatomical features of mosquito specimen can greatly aid researchers for mosquito studies. In this study, the three-dimensional imaging capabilities of optical coherence tomography (OCT) for structural analysis of Anopheles sinensis mosquitoes has been demonstrated. The anatomical features of An. sinensis head, thorax, and abdomen regions along with internal morphological structures like foregut, midgut, and hindgut were studied using OCT imaging. Two-dimensional (2D) and three-dimensional (3D) OCT images along with histology images were helpful for the anatomical analysis of the mosquito specimens. From the concurred results and by exhibiting this as an initial study, the applicability of OCT in future entomological researches related to mosquitoes and changes in its anatomical structure is demonstrated