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Articles 1 - 30 of 541
Full-Text Articles in Physics
Optimisation Of Photosensitive Recording Materials For Broadband Holographic Optical Elements, Michael Murray
Optimisation Of Photosensitive Recording Materials For Broadband Holographic Optical Elements, Michael Murray
Doctoral
The introduction of broadband (white) LED outdoor lighting has led to significant energy savings. However, this has come at the cost of increased light pollution which has negative impacts both on ecological systems and human health. This light pollution is largely the result of the lack of control measures for the directionality of the light emitted by outdoor LED lighting. The lack of directionality also results in higher energy consumption in order to compensate for the light scattered to the atmosphere and sufficiently illuminate the target area. In this thesis holographic optical elements (HOEs) are proposed as a complementary technology …
Reflection Hoes Recorded On Photopolymerisable Glass Layers: A Step Towards Holographic Mirrors For Ar Technologies, David Ma, Suzanne Martin, Mohamed Oubaha, Tatsiana Mikulchyk
Reflection Hoes Recorded On Photopolymerisable Glass Layers: A Step Towards Holographic Mirrors For Ar Technologies, David Ma, Suzanne Martin, Mohamed Oubaha, Tatsiana Mikulchyk
Conference Papers
Reflection Holographic Optical Elements (HOEs) offer a great potential for Augmented Reality (AR) display technologies due to their unique capability to redirect light with the predetermined wavelength in the opposite direction to the reconstructing light. AR displays based on HOEs enable a large variety of potential applications which necessitates the development of HOEs with long-term stable performance in challenging ambient conditions. Here, we present a study of the holographic recording capability of a photopolymerizable hybrid sol-gel (PHSG) which has shown to be a robust and water/temperature resistant material. Using optimal recording conditions, diffraction efficiency up to 18% has been achieved …
Shrinkage Study In Photopolymerisable Hybrid Sol-Gel Through Holographic Patterning, Jamshed Aftab, Izabela Naydenova, Tatsiana Mikulchyk
Shrinkage Study In Photopolymerisable Hybrid Sol-Gel Through Holographic Patterning, Jamshed Aftab, Izabela Naydenova, Tatsiana Mikulchyk
Articles
Photopolymerisation induced shrinkage of holographic materials is one of the main factors which needs to be considered for designing holographic optical elements (HOEs) with high accuracy in light redirection with maximum efficiency. This work studies the shrinkage in photopolymerisable hybrid sol-gel (PHSG) by examining the properties of volume transmission gratings recorded in PHSG layers. It explores both the dependence of shrinkage on the holographic grating parameters (thickness, spatial frequency, slant angle) and the effect of material aging. By using the fringe-plane rotation model, shrinkage is found to have the maximum value of 1.37 % at 765 lines/mm (19.36° slant angle) …
Investigation Of A Polymer-Based Holographic Grating For Visible Light Dosimetry Using A Bleachable Dye, Saoirse Maher, Denise Denning, Jackie Mccavana Dr., Seán Cournane Dr., Suzanne Martin Dr., Dervil Cody
Investigation Of A Polymer-Based Holographic Grating For Visible Light Dosimetry Using A Bleachable Dye, Saoirse Maher, Denise Denning, Jackie Mccavana Dr., Seán Cournane Dr., Suzanne Martin Dr., Dervil Cody
Conference Papers
Holographic sensors are of interest for a range of sensing tasks because of their high sensitivity, rapid response time, broad dynamic range, lightweight characteristics, and design flexibility. The practical application of holography makes it possible to design optical sensors that are effective in the visible and near-infrared ranges. The objective of this research is to construct a holographic grating that is customised to provide quantitative data in visible light dosimetry applications. Upon exposure to visible light, the proposed holographic grating will produce a measurable change in diffraction efficiency based on the bleaching of the grating material. In the evolution of …
Doping Hybrid Photopolymerisable Glass With Bodipy Photosensitiser: An Efficient Approach To Improve Uv-Resistance, Luca Sorridente, Tatsiana Mikulchyk, Metodej Dvoracek, Mikhail A. Filatov, Izabela Naydenova, Kevin P. Murphy
Doping Hybrid Photopolymerisable Glass With Bodipy Photosensitiser: An Efficient Approach To Improve Uv-Resistance, Luca Sorridente, Tatsiana Mikulchyk, Metodej Dvoracek, Mikhail A. Filatov, Izabela Naydenova, Kevin P. Murphy
Conference Papers
The development of photosensitive materials with improved performance and extended functionality is crucial for advancing holographic technologies. This study presents the modification and characterization of a recently reported photopolymerisable glass composition, focusing on achieving an optimal balance between maximizing photosensitivity of the material during recording and minimizing the impact of UV light on the performance of the recorded holographic structure. Building on these findings, the ultimate goal is to develop UV-resistant holographic optical elements for wavefront sensing in space applications. The research approach is based on introducing a photosensitiser with weaker UV absorption than the typically used in this material …
Modelling The Formation Of Unslanted Holographic Gratings In Hybrid Photopolymer Media, Jack Lyons, Dana Mackey, Izabela Naydenova
Modelling The Formation Of Unslanted Holographic Gratings In Hybrid Photopolymer Media, Jack Lyons, Dana Mackey, Izabela Naydenova
Articles
The theoretical modelling of holographic recording in photopolymers has been an important tool in their optimisation. More complex, hybrid organic/inorganic photopolymers have been developed in pursuit of materials with higher sensitivity, low shrinkage, high dynamic range and environmental stability. Recent attempts to augment the existing models for the redistribution of inorganic nanoparticles in holographic recording were successful but there is still a knowledge gap in regards to modelling optical losses, mutual cross-diffusion, the formation of slanted holographic gratings and polymerization induced shrinkage in hybrid photopolymer media. This paper will describe a novel approach to modelling the formation of unslanted holographic …
Highly Sensitive Diffractive Optical Structures For Detection Of Volatile Organic Compounds, Faolan Radford Mcgovern
Highly Sensitive Diffractive Optical Structures For Detection Of Volatile Organic Compounds, Faolan Radford Mcgovern
Doctoral
From aerospace to agriculture, sensors play a fundamental role in many aspects of modern life. Sensors form an integral part of the complex systems and devices required for the continued functioning and development of services and industries across society. The use of sensors is paramount in areas affecting human health, one such area being the monitoring of indoor air quality, in particular the detection of volatile organic compounds (VOCs). Human contact with VOCs has been associated with many health complications, including skin and eye irritation, cardiovascular damage, and cancers. Optical, electrical, gravimetric, and chemical sensors have been developed for VOC …
Improving The Performance Of The Modal Holographic Wavefront Sensor By Adapting To Prevailing Turbulence Conditions: Experimental Verification, Andreas Zepp, Emma Branigan, Kevin Murphy, Szymon Gladysz
Improving The Performance Of The Modal Holographic Wavefront Sensor By Adapting To Prevailing Turbulence Conditions: Experimental Verification, Andreas Zepp, Emma Branigan, Kevin Murphy, Szymon Gladysz
Conference Papers
The modal holographic wavefront sensor offers a promising alternative to established wavefront sensing techniques. Since the strengths of individual aberration modes are directly measured, there is no need for time-consuming signal processing and wavefront reconstruction. Bandwidths up to three orders of magnitude higher than those of commercial wavefront sensors can in principle be achieved. However, in practice the accuracy of measurements is compromised by intermodal crosstalk, which arises when the wavefront exhibits additional aberrations to those encoded in the modal wavefront sensor. This issue is particularly prominent when measuring wavefronts disturbed by atmospheric turbulence. To mitigate the effects of intermodal …
Confocal Raman Spectroscopy Coupled With In Vitro Permeation Testing To Study The Effects Of Formalin Fixation On The Skin Barrier Function Of Reconstructed Human Epidermis, Hichem Kichou, Franck Bonnier, Amanda C. Caritá, Hugh Byrne, Igor Choupra, Emilie Munnier
Confocal Raman Spectroscopy Coupled With In Vitro Permeation Testing To Study The Effects Of Formalin Fixation On The Skin Barrier Function Of Reconstructed Human Epidermis, Hichem Kichou, Franck Bonnier, Amanda C. Caritá, Hugh Byrne, Igor Choupra, Emilie Munnier
Articles
Confocal Raman Spectroscopy is recognised as a potent tool for molecular characterisation of biological specimens. There is a growing demand for In Vitro Permeation Tests (IVPT) in the pharmaceutical and cosmetic areas, increasingly conducted using Reconstructed Human Epidermis (RHE) skin models. In this study, chemical fixation of RHE in 10% Neutral Buffered Formalin for 24 hours has been examined for storing RHE samples at 4°C for up to 21 days. Confocal Raman Spectroscopy, combined with Principal Components Analysis, revealed the molecular-level effects of fixation, notably in protein and lipid conformation within the stratum corneum and viable epidermis. IVPT by means …
Three-Dimensional Printing Limitations Of Polymers Reinforced With Continuous Stainless Steel Fibres And Curvature Stiffness, Alison J. Clarke, Andrew N. Dickson, Vladimir Milosavljevic, Denis P. Dowling
Three-Dimensional Printing Limitations Of Polymers Reinforced With Continuous Stainless Steel Fibres And Curvature Stiffness, Alison J. Clarke, Andrew N. Dickson, Vladimir Milosavljevic, Denis P. Dowling
Articles
This study investigates the printability limitations of 3D-printed continuous 316L stainless steel fibre-reinforced polymer composites obtained using the Materials Extrusion (MEX) technique. The objective was to better understand the geometric printing limitations of composites fabricated using continuous steel fibres, based on a combination of bending stiffness testing and piezoresistive property studies. The 0.5 mm composite filaments used in this study were obtained by co-extruding polylactic acid (PLA), with a 316 L stainless steel fibre (SSF) bundle. The composite printability limitations were evaluated by the printing of a series of ’teardrop’ shaped geometries with angles in the range from 5◦ to …
Wavefront Sensor Based On Angle Selectivity Of An Optical Filter, Andreas Zepp, Emma Branigan, Julien Garnier, Kevin Murphy, Raphael Bellossi, Karin Stein, Szymon Gladysz
Wavefront Sensor Based On Angle Selectivity Of An Optical Filter, Andreas Zepp, Emma Branigan, Julien Garnier, Kevin Murphy, Raphael Bellossi, Karin Stein, Szymon Gladysz
Conference Papers
The effectiveness of free-space laser communications is limited due to wavefront deformations caused by atmospheric optical turbulence. To determine these deformations, we propose a wavefront sensor that utilizes the angular selectivity of an optical transmission filter to measure the first derivative of the wavefront. The transmission filter converts the gradients of the incident wavefront into an intensity distribution. For each direction (x and y) this distribution is captured twice, with different angles between filter and optical axis for each measurement. The contrast of both measurements (calculated for each pixel of the used detector) and the local gradients of the wavefront …
Comparing Thin And Volume Regimes Of Analog Holograms For Wavefront Sensing, Emma Branigan, Andreas Zepp, Suzanne Martin, Matthew Sheehan, Szymon Gladysz, Kevin Murphy
Comparing Thin And Volume Regimes Of Analog Holograms For Wavefront Sensing, Emma Branigan, Andreas Zepp, Suzanne Martin, Matthew Sheehan, Szymon Gladysz, Kevin Murphy
Articles
Two analog holographic wavefront sensors, for measurement of defocus, have been fabricated as both thin and volume phase transmission holograms in a self-developing photopolymer. This represents the first reported direct comparison of hologram regimes when designed for wavefront sensing. An analysis of the effect of crosstalk in the presence of one other aberration mode (astigmatism X (0/90°), coma X (horizontal), and primary spherical aberration) was carried out with each version of the sensor. The performance of thin and volume analog holographic wavefront sensors was characterized under emulated conditions associated with moderate atmospheric turbulence.
Thermal Effects On The Voc-Sensitive Polydimethylsiloxane Holographic Gratings, Aleksandra Hernik, Faolan Radford Mcgovern, Patrick Iftime, Izabela Naydenova
Thermal Effects On The Voc-Sensitive Polydimethylsiloxane Holographic Gratings, Aleksandra Hernik, Faolan Radford Mcgovern, Patrick Iftime, Izabela Naydenova
Conference Papers
The imperative for monitoring volatile organic compounds (VOCs) emerges from their harmful impact on human health when inhaled excessively over a long term. Polydimethylsiloxane (PDMS), valued for its transparency and excellent flexibility, has already been demonstrated as a promising biocompatible and cost-effective transducer for optical VOCs sensing. Moreover, it facilitates further functionalisation with adsorbing materials to enhance sensitivity and selectivity for specific VOCs detection. We fabricated and examined PDMS-based surface diffraction gratings after exposure to selected VOCs, demonstrating different response for polar and non-polar molecules. Investigated gratings were prepared by replicating sinusoidal surface relief structures inscribed in acrylamide photopolymer using …
Investigation Of The Uv-Resistance Of Photopolymerisable Glass For Space Applications, Luca Sorridente, Tatsiana Mikulchyk, Izabela Naydenova, Kevin Murphy
Investigation Of The Uv-Resistance Of Photopolymerisable Glass For Space Applications, Luca Sorridente, Tatsiana Mikulchyk, Izabela Naydenova, Kevin Murphy
Articles
The progress of space based scientific research leads to an increasing demand for more efficient and less bulky instruments. Conventional refractive elements make up a critical part of many optical instruments launched into space; however, they can be bulky and heavy. Holographic optical elements are an efficient alternative to replace the conventional optical elements as they are lightweight and can be miniaturized. Current materials typically used for volume holographic optical elements are not robust enough for use in space environment. Recently a promising photopolymerisable glass has been developed using a sol-gel technique, which can provide dry layers suitable for holographic …
Photopolymer Material Durability And Safety In Holographic Diffusers For Visual Applications, Matthew Hellis, Alan Casey, Edoardo Splendi, Suzanne Martin, Matthew Sheehan, Kevin Murphy
Photopolymer Material Durability And Safety In Holographic Diffusers For Visual Applications, Matthew Hellis, Alan Casey, Edoardo Splendi, Suzanne Martin, Matthew Sheehan, Kevin Murphy
Articles
This study introduces novel holographic diffuser applications employing acrylamide- or diacetone acrylamide-based photopolymers, patterned within the volume on a micron scale by a single-beam holographic recording process. These diffusers have previously been presented as potential treatments for amblyopia and diplopia. This work has now been extended to spectrometric analysis to determine their properties under broadband light. Diffusive elements with higher diffusion efficiencies exhibited a marginal reduction (< 5%) in diffusion efficiency across most of the visible spectrum. Given the intended application of these holographic diffusers, cytotoxicity assessments were also performed. This is significant as there is a difference in toxicity between the crystalline acrylamide (classified as a category 3 material) and diacetone acrylamide (classified as a category 4 material). The findings indicated substantially lower toxicity in holograms produced with diacetone acrylamide-based photopolymer. The accelerated ageing of both formulations of holographic diffusers indicated that the acrylamide-based holographic diffusers did not reduce efficacy in the 292 days of ageing. The diacetone acrylamide-based holographic diffusers exhibited reduced efficacy by day 182. Despite this, both formulations have been shown to perform for prolonged periods as the treatment modality would require. These results emphasise that holographic diffusers exhibit minimal spectral impact, and longevity on the scale of treatment regimes which are crucial considerations for their prospective use case as treatments for amblyopia and diplopia.
Modeling Redistribution Of Nanozeolites In Holographic Recording, Dana Mackey, Jack Lyons Dr, Izabela Naydenova
Modeling Redistribution Of Nanozeolites In Holographic Recording, Dana Mackey, Jack Lyons Dr, Izabela Naydenova
Articles
Zeolite doped photopolymers have been studied experimentally due to their potential application in the develop- ment of optical sensors. It has been shown that dopant redistribution can be achieved by holographic recording and has a direct influence on the sensitivity of the recorded grating. To achieve better theoretical understanding of these processes, this paper proposes an extended photopolymerization-diffusion mathematical model for describing the dynamics of nanozeolite redistribution during recording in an acrylamide-based photopolymer. Using numerical simulations of this model, we investigate how recording conditions, dopant transport parameters, and initial load affect the refractive index modulation of the resulting photonic structure.
Holographic Multiplexing In A Photopolymerisable Hybrid Sol-Gel, Pamela Stoeva, Tatsiana Mikulchyk, Izabela Naydenova, Kevin Murphy
Holographic Multiplexing In A Photopolymerisable Hybrid Sol-Gel, Pamela Stoeva, Tatsiana Mikulchyk, Izabela Naydenova, Kevin Murphy
Articles
Holographic multiplexing techniques enhance functionality and information storage by leveraging the inherent selectivity of holograms. This is crucial for advancing holographic sensors, which excel in simultaneously detecting multiple parameters from a single input signal. This study explores the potential of the recent photopolymerisable hybrid sol-gel (PHSG) material for application in Space sensing systems through the investigation of its holographic angular multiplexing capabilities. For the first time, to the best of our knowledge, we report the successful recording of up to five angularly multiplexed gratings with diffraction efficiencies (DE) ≥ 15% in 187 ± 18 µm PHSG layers. A 3 mW/cm2 …
Spectralomics – Towards A Holistic Adaptation Of Label Free Spectroscopy, Hugh Byrne
Spectralomics – Towards A Holistic Adaptation Of Label Free Spectroscopy, Hugh Byrne
Articles
Vibrational spectroscopy, largely based on infrared absorption and Raman scattering techniques, is much vaunted as a label free approach, delivering a high content, holistic characterisation of a sample, with demonstrable applications in a broad range of fields, from process analytical technologies and preclinical drug screening, to disease diagnostics, therapeutics, prognostics and personalised medicine. However, in the analysis of such complex systems, a trend has emerged in which spectral analysis is reduced to the identification of individual peaks, based on reference tables of assignments derived from literature, which are then interpreted as biomarkers. More sophisticated analysis attempts to unmix the spectrum …
Modelling Hoe Performance With An Extended Source; Experimental Investigation Using Misaligned Point Sources, Jorge Lasarte, Kevin Murphy, Izabela Naydenova, Maria Victoria Collados, Jesús Atencia, Suzanne Martin
Modelling Hoe Performance With An Extended Source; Experimental Investigation Using Misaligned Point Sources, Jorge Lasarte, Kevin Murphy, Izabela Naydenova, Maria Victoria Collados, Jesús Atencia, Suzanne Martin
Articles
Holographic optical elements (HOEs) have the potential to enable more compact, versatile, and lightweight optical designs, but many challenges remain. Volume HOEs have the advantage of high diffraction efficiency, but they present both chromatic selectivity and chromatic dispersion, which impact their use with wide spectrum light sources. Single-color light emitting diode (LED) sources have a narrow spectrum that reduces these issues and this makes them better suited for use with volume HOEs. However, the LED source size must be taken into consideration for compact volume HOE-LED systems. To investigate the design limits for compact HOE-LED systems, a theoretical and experimental …
Hamiltonian Models For The Propagation Of Long Gravity Waves, Higher-Order Kdv-Type Equations And Integrability, Rossen Ivanov
Hamiltonian Models For The Propagation Of Long Gravity Waves, Higher-Order Kdv-Type Equations And Integrability, Rossen Ivanov
Book chapter/book
A single incompressible, inviscid, irrotational fluid medium bounded above by a free surface is considered. The Hamiltonian of the system is expressed in terms of the so-called Dirichlet-Neumann operators. The equations for the surface waves are presented in Hamiltonian form. Specific scaling of the variables is selected which leads to a KdV approximation with higher order nonlinearities and dispersion (higher-order KdV-type equation, or HKdV). The HKdV is related to the known integrable PDEs with an explicit nonlinear and nonlocal transformation.
Spectroscopic Serology For The Quantitative Screening Of Carotenoid Compounds In Human Blood – Correlation With Clinical Macular Pigment Factors, Joy Udensi
Doctoral
Carotenoids represent a wide range of naturally occurring pigmented compounds with an obvious presence in many plants and some animals. They constitute an important component of the human diet and have been widely recognised for their antioxidant and vision protection advantages.
Disaggregating Longer-Term Trends From Seasonal Variations In Measured Pv System Performance, Chibuisi Chinasaokwu Okorieimoh, Brian Norton, Michael Conlon
Disaggregating Longer-Term Trends From Seasonal Variations In Measured Pv System Performance, Chibuisi Chinasaokwu Okorieimoh, Brian Norton, Michael Conlon
Articles
Photovoltaic (PV) systems are widely adopted for renewable energy generation, but their performance is influenced by complex interactions between longer-term trends and seasonal variations. This study aims to remove these factors and provide valuable insights for optimising PV system operation. We employ comprehensive datasets of measured PV system performance over five years, focusing on identifying the distinct contributions of longer-term trends and seasonal effects. To achieve this, we develop a novel analytical framework that combines time series and statistical analytical techniques. By applying this framework to the extensive performance data, we successfully break down the overall PV system output into …
Analysis Of Macular Pigment Carotenoids In Human Blood Serum Of Glaucoma Patients As A Measure Of Ocular Health: A Raman Spectroscopic Study., Joy Udensi, Ekaterina Loskutova, James Loughman, Hugh J. Byrne
Analysis Of Macular Pigment Carotenoids In Human Blood Serum Of Glaucoma Patients As A Measure Of Ocular Health: A Raman Spectroscopic Study., Joy Udensi, Ekaterina Loskutova, James Loughman, Hugh J. Byrne
Datasets
Carotenoids are a major component of the human diet and have been widely studied for their antioxidant, and vision protection roles in the human body, and dietary supplementation is promoted in particular for ocular health. An initial trial (European Nutrition in Glaucoma Management (ENIGMA)), which assessed macular pigment optical density (MPOD) as well as ocular structural, functional and perceptual parameters before and after the 18-month supplementation of glaucoma patients with macular pigment (MP) carotenoids (lutein, zeaxanthin, meso-zeaxanthin), confirmed supplementation significantly improved the clinical ocular health of participants. Blood contains all major dietary carotenoids, presenting it as a suitable and efficient …
Development Of An Optical Test Bed For The Fabrication And Characterisation Of An Analog Holographic Wavefront Sensor, Emma Branigan, Andreas Zepp, Suzanne Martin, Matthew Sheehan, Szymon Gladysz, Kevin Murphy
Development Of An Optical Test Bed For The Fabrication And Characterisation Of An Analog Holographic Wavefront Sensor, Emma Branigan, Andreas Zepp, Suzanne Martin, Matthew Sheehan, Szymon Gladysz, Kevin Murphy
Conference Papers
A new holographic recording setup has been developed for the fabrication of single- and multi-mode photopolymer-based analog holographic wavefront sensors. A second setup has been built and used to characterise the sensor at several wavelengths.
Renormalized Stress-Energy Tensor For Scalar Fields In Hartle-Hawking, Boulware, And Unruh States In The Reissner-Nordström Spacetime, Julio Arrechea, Cormac Breen, Adrian Ottewill, Peter Taylor
Renormalized Stress-Energy Tensor For Scalar Fields In Hartle-Hawking, Boulware, And Unruh States In The Reissner-Nordström Spacetime, Julio Arrechea, Cormac Breen, Adrian Ottewill, Peter Taylor
Articles
In this paper, we consider a quantum scalar field propagating on the Reissner-Nordström black hole spacetime. We compute the renormalized stress-energy tensor for the field in the Hartle-Hawking, Boulware and Unruh states. When the field is in the Hartle-Hawking state, we renormalize using the recently developed “extended coordinate” prescription. This method, which relies on Euclidean techniques, is very fast and accurate. Once, we have renormalized in the Hartle-Hawking state, we compute the stress-energy tensor in the Boulware and Unruh states by leveraging the fact that the difference between stress-energy tensors in different quantum states is already finite. We consider a …
Raman Spectroscopic Analysis Of Human Serum Samples Of Convalescing Covid-19 Positive Patients, Hugh Byrne, Naomi Jackson, Jaythoon Hassan
Raman Spectroscopic Analysis Of Human Serum Samples Of Convalescing Covid-19 Positive Patients, Hugh Byrne, Naomi Jackson, Jaythoon Hassan
Articles
Rapid screening, detection and monitoring of viral infection is of critical importance, as exemplified by the rapid spread of SARS-CoV-2, leading to the worldwide pandemic of COVID-19. This is equally the case for the stages of patient convalescence as for the initial stages of infection, to understand the medium and long terms effects, as well as the efficacy of therapeutic interventions. Optical spectroscopic techniques potentially offer an alternative to currently employed techniques of screening for the presence, or the response to infection. In this study, the ability of Raman spectroscopy to distinguish between samples of the serum of convalescent COVID-19 …
Raman Spectral Cytopathology For Cancer Diagnostic Applications, Fiona Lyng, Damian Traynor, Isha Behl, Declan O'Dea, Hugh Byrne
Raman Spectral Cytopathology For Cancer Diagnostic Applications, Fiona Lyng, Damian Traynor, Isha Behl, Declan O'Dea, Hugh Byrne
Books/Book Chapters
Histopathology is currently regarded as the “gold standard” patient sampling technique for cancer diagnostics. It involves extraction of a tissue sample, or biopsy, which is then sectioned and stained for evaluation by a pathologist [1]. Cytopathology, on the other hand, is the field of disease diagnosis at the cellular level [2], necessitating only the microscopic evaluation of samples of cells which can be harvested by less invasive methods such as exfoliative brushing, needle probes or from biofluids. Based on the identification of abnormalities in cellular appearance, cytopathology is currently widely used to aid in the screening of cancer, as well …
Optical Characterisation Of Holographic Diffusers And Bangerter Foils For Treatment Of Amblyopia, Matthew Hellis, Suzanne Martin, Matthew Sheehan, Kevin Murphy
Optical Characterisation Of Holographic Diffusers And Bangerter Foils For Treatment Of Amblyopia, Matthew Hellis, Suzanne Martin, Matthew Sheehan, Kevin Murphy
Articles
Amblyopia is a significant issue for children worldwide, and current treatment methods have drawbacks that can hinder treatment effectiveness and/or patient experience. This study proposes a new treatment method using holographic diffusers while also comparing their optical characteristics to a current treatment method (Bangerter foils). Holographic diffusers were developed by optically patterning thin polymer layers on a micron scale. Two compositions of photopolymer (acrylamide and diacetone acrylamide based) are analysed herein. Characterisation shows that holographic diffusers of either composition can achieve a wide range of on-axis intensity reductions, allowing for precise and customisable treatment levels by altering recording exposure time …
Modelling Hoe Performance With An Extended Source; Experimental Investigation Using Misaligned Point Sources, Jorge Lasarte, Kevin Murphy, Izabela Naydenova, Jesús Atencia, Mª Victoria Collados, Suzanne Martin
Modelling Hoe Performance With An Extended Source; Experimental Investigation Using Misaligned Point Sources, Jorge Lasarte, Kevin Murphy, Izabela Naydenova, Jesús Atencia, Mª Victoria Collados, Suzanne Martin
Conference Papers
Holographic Optical Elements (HOEs) have the potential to enable more compact, versatile and lightweight optical designs, but many challenges remain. Volume HOE’s have the advantage of high diffraction efficiency but they present both chromatic selectivity and chromatic dispersion which impact on their use with wide spectrum light sources. Single-colour LED sources have a narrow spectrum that reduces these issues and this makes them better suited for use with volume HOEs. However, the LED source size must be taken into consideration for compact volume HOE-LED systems. To investigate the design limits for compact HOE-LED systems, a theoretical and experimental study was …
Analog Holographic Wavefront Sensor For Defocus And Spherical Aberration Measurement Recorded In A Photopolymer, Emma Branigan, Suzanne Martin, Matthew Sheehan, Kevin Murphy
Analog Holographic Wavefront Sensor For Defocus And Spherical Aberration Measurement Recorded In A Photopolymer, Emma Branigan, Suzanne Martin, Matthew Sheehan, Kevin Murphy
Articles
An analog holographic wavefront sensor (AHWFS), for measurement of low and high order (defocus and spherical aberration) aberration modes has been developed as volume phase holograms in a photopolymer recording medium. This is the first time that high order aberrations such as spherical aberration can be sensed using a volume hologram in a photosensitive medium. Both defocus and spherical aberration were recorded in a multi-mode version of this AHWFS. Refractive elements were used to generate a maximum and minimum phase delay of each aberration which were multiplexed as a set of volume phase holograms in an acrylamide based-photopolymer layer. The …