An intelligent and confident system for automatic surface defect quantification in 3D

Automatic surface defect inspection within mass production of high-precision components is growing in demand and requires better measurement and automated analysis systems. Many manufacturing industries may reject manufactured parts that exhibit even minor defects, because a defect might result in an operational failure at a later stage. Defect quantification (depth, area and volume) is a key element in quality assurance in order to determine the pass or failure criterion of manufactured parts. Existing human visual analysis of surface defects is qualitative and subjective to varying interpretation. Non-contact and three dimensional (3D) analyses should provide a robust and systematic quantitative approach for defect analysis. Various 3D measuring instruments generate point cloud data as an output, although they work on different physical principles. Instrument’s native software processing of point cloud data is often subject to issues of repeatability and may be non-traceable causing significant concern with data confidence. This work reports the development of novel traceable surface defect artefacts produced using the Rockwell hardness test equipment on flat metal plate, and the development of a novel, traceable, repeatable, mathematical solution for automatic defect detection and quantification in 3D. Moreover, in order to build-up the confidence in automatic defect analysis system and generated data, mathematical simulated defect artefacts (soft-artefact) have been created. This is then extended to a surface defect on a piston crown that is measured and quantified using a parallel optical coherence tomography instrument integrated with 6 axis robot. The results show that surface defect quantification using implemented solution is efficient, robust and more repeatable than current alternative approaches

Polymer based microscale and nanoscale technologies for optical and biomedical application

Polymer based micro and nano systems has emerged as a mainstream research in recent times with advent of bio-inspired design of opto-MEMS as wells as bio-MEMS. Polymers have tunable materials characteristics ranging for elastic to brittle nature, optically transparent and biocompatible and biodegradable for application in optics and biomedicine. I tackled four different technological challenges in this research work using novel biomimetic design and biopolymers as listed below. First, I designed wide acceptance angle thin and flat miniaturized solar concentrator by mimicking the wide acceptance angle found in compound eye of insects. I integrated lens, conic spacer and light guide to concentrate and redirect sunlight into small area where PV cell can be installed. My design can have total concentration up to ~40 for acceptance angle of 15ð. Second, I designed and fabricated automated light control switch using IR part of solar spectrum and to change a paraffin micro-chamber volume and actuate the cantilever structure. The cantilever structure when activated frustrates the TIR guided light in the lightguide and control the illumination level. We obtained rms value of illumination change to be 0.012 for input change of 0.018. Third, I developed rapid, inexpensive, reproducible method to make nanoscale patterns in PLLA films using replica-molding techniques. We produce very high fidelity replication of PLLA using double replication from master polycarbonate to PDMS mold and from PDMS mold to PLLA film by drop casting process. The surface characteristics of the nano-patterned film changed drastically form hydrophilic to hydrophobic due to patterning. We also investigate the drug coating process in this film for its use in controlled drug release platform. Finally, I used the drug coated and nano-patterned PLLA film for its potential application in biodegradable coronary stents. We fabricated the stents by rolling the PLLA films into the tube. The controlled drug release was studied by releasing the control and patterned PLLA surface into phosphate buffer saline. We used advanced high performance liquid chromatography coupled with mass spectrometer to measure the amount of drug released as a function of time. The nano-patterned surface has up to 20% slower drug release rate in comparison to the flat surface

Texture and Colour in Image Analysis

Research in colour and texture has experienced major changes in the last few years. This book presents some recent advances in the field, specifically in the theory and applications of colour texture analysis. This volume also features benchmarks, comparative evaluations and reviews

A Review and Analysis of Automatic Optical Inspection and Quality Monitoring Methods in Electronics Industry

Electronics industry is one of the fastest evolving, innovative, and most competitive industries. In order to meet the high consumption demands on electronics components, quality standards of the products must be well-maintained. Automatic optical inspection (AOI) is one of the non-destructive techniques used in quality inspection of various products. This technique is considered robust and can replace human inspectors who are subjected to dull and fatigue in performing inspection tasks. A fully automated optical inspection system consists of hardware and software setups. Hardware setup include image sensor and illumination settings and is responsible to acquire the digital image, while the software part implements an inspection algorithm to extract the features of the acquired images and classify them into defected and non-defected based on the user requirements. A sorting mechanism can be used to separate the defective products from the good ones. This article provides a comprehensive review of the various AOI systems used in electronics, micro-electronics, and opto-electronics industries. In this review the defects of the commonly inspected electronic components, such as semiconductor wafers, flat panel displays, printed circuit boards and light emitting diodes, are first explained. Hardware setups used in acquiring images are then discussed in terms of the camera and lighting source selection and configuration. The inspection algorithms used for detecting the defects in the electronic components are discussed in terms of the preprocessing, feature extraction and classification tools used for this purpose. Recent articles that used deep learning algorithms are also reviewed. The article concludes by highlighting the current trends and possible future research directions.Framework of the IQONIC Project; European Union’s Horizon 2020 Research and Innovation Program

Non-volatile liquid-film-embedded microfluidic valve for microscopic evaporation control and contactless bio-fluid delivery applications

Quick evaporation speed of microfluids can cause many unexpected problems and failures in various microfluidic devices and systems. In this dissertation, a new evaporation speed controlling method is demonstrated using a thin liquid-film based microfluidic valve. Microfluidic droplet ejectors were designed, fabricated and integrated with the liquid-film based microfluidic valve. The thin liquid film with nonvolatility and immiscibility exhibited excellent microfluidic valve functionality without any stiction problem between valve components, and provided a very effective evaporation protection barrier for the microfluids in the device. Successful evaporation control by the liquid-film-embedded (LiFE) microfluidic valve has been demonstrated. In addition, guided actuation of the microfluidic valve along predefined paths was successfully achieved using newly developed oil-repellent surfaces, which were later used for developing ‘virtual walls’ for confining low surface tension liquids within predefined areas. Moreover, bioinspired slippery surfaces for aiding the microfluidic valve along the ejector surface have also been developed. These slippery surfaces were evaluated for their effectiveness in reducing microfluidic valve driving voltages. Finally, a sliding liquid drop (SLID) shutter technique has been developed for a normally closed functionality with aid from nanostructures. The SLID shutter resolves many issues found in the previous LiFE microfluidic valve. Smooth and successful printing results of highly volatile bio-fluids have been demonstrated using the SLID shutter technique. I envision that these demonstrated techniques and developed tools have immense potential in various microfluidic applications

Application of polarized Raman spectroscopy for analysis of phase transitions and anisotropic behavior of soft condensed matter

The importance of soft matter research, as a major class of materials including liquid crystals, polymers, colloids, emulsions, and forms, is attributed to the behavior resemblances in each branch of soft matter responding to the external perturbations. Hence, one of the most required inquiries in soft matter physics is understanding how the structures with characteristic length scales evolve in response to external perturbations, and concomitant phase transitions. We have focused on adopting polarized Raman spectroscopy to probe phase transitions in soft materials consisting of anisometric components and the evolution of molecular orientational ordering as a complementary tool to other methodologies, but distinct in some respects. The primary task is quantifying the degree of molecular orientation, i.e., obtaining orientational order parameters, in liquid crystal (LCs) system. Thermal evolution of orientation degree in a hitherto elusive biaxial nematic (Nb) phase as well as a commonly known uniaxial nematic (Nu) phase were interrogated from the measurements of anisotropy in polarized Raman intensities. We demonstrated reliable and applicable method to quantify the orientation degree for systems possessing anisotropic ordering. We also addressed a strong potential of Raman spectroscopy that the changes of vibrational energy reflect the variations of intermolecular interactions and structural changes on the molecular level induced by phase transitions. As a subfield of soft matter, we characterized phase transitions and anisotropic ordering observed in an evaporating conjugated polymer solution and elucidated the mechanism of the entities undergoing phase transitions using mainly polarized Raman spectroscopy. In addition, we have shown that tracking Raman spectral changes can provide valuable information for understanding structure-property relations when the measurements of the evolution in physical properties are carried out simultaneously.PhDCommittee Chair: Srinivasarao, Mohan; Committee Member: El-Sayed, Mostafa; Committee Member: Fernandez, Alberto; Committee Member: Griffin, Anselm; Committee Member: Park, Jung Ok; Committee Member: Reichmanis, Elsa; Committee Member: Rey, Alejandro; Committee Member: Tolbert, Lare

The Flexoelectro-optic Effect for Photonics Applications

The flexo-electro-optics effect in chrial nematic liquid crystals is developed towards new photonics and display applications. The short-pitch uniform-standing helix device is proposed, and improved performance in uniform lying helix devices through polymer network stabilisation is shown.This thesis comprises an account of research carried out into the flexoelectro-optic effect, as observed in chiral nematic liquid crystals, and its potential for application in fibre optic communications components. The flexoelectro-optic effect provides a mechanism of fast, analogue rotation of the optic axis in chiral nematic materials via the application of an electric field to the sample. In particular, bimesogenic liquid crystal materials exhibit very large flexoelectro-optic tilt angles, and a large tilt angle per unit field in comparison to other mesogenic materials. In this work a new geometry for the flexoelectro-optic effect is developed in which the chiral nematic liquid crystal is aligned with its helical axis along the normal to the cell walls and the electric field is applied in the plane of the cell. It is shown that polymer stabilization of this device by the addition of a small percentage of reactive mesogen to mixture increases greatly the ability of the device to withstand high amplitude a.c. electric fields. Applied fields of up to 6.8 V/μm are shown to induce a maximum birefringence of ∆n=0.037, due to both flexoelectric and dielectric coupling, and ∆n=0.012 due to flexoelectric coupling only in a sample based on symmetric difluorinated bimesogens. This induced birefringence is shown to consistently respond to field application and removal on the sub millisecond timescale. Polymer stabilization of the same mixtures in the uniform lying helix texture is shown to affect the electro-optic response of the samples in a manner which is dependent on the concentration of reactive mesogen used, and the temperature at which the reactive mesogen is cured. A concentration of approximately 3% weight/weight, however, has little detrimental impact on the device characteristics, and curing of the sample at the lower end of the chiral nematic temperature range is shown to allow optimization of both tilt angle and response time of the samples. The effect is also employed to demonstrate a new method of fast electrical tuning of the output wavelength from chiral nematic photonic band edge lasers. An 8nm shift was induced in these devices by a 3.5 V/μm applied field.EPSR