Physics Commons^™

Spectral Cross Correlation As A Supervised Approach For The Analysis Of Complex Raman Datasets: The Case Of Nanoparticles In Biological Cells, Mark Keating, Franck Bonnier, Hugh Byrne

Articles

Spectral Cross-correlation is introduced as a methodology to identify the presence and subcellular distribution of nanoparticles in cells. Raman microscopy is employed to spectroscopically image biological cells previously exposed to polystyrene nanoparticles, as a model for the study of nano-bio interactions. The limitations of previously deployed strategies of K-means clustering analysis and principal component analysis are discussed and a novel methodology of Spectral Cross Correlation Analysis is introduced and compared with the performance of Classical Least Squares Analysis, in both unsupervised and supervised modes. The previous study demonstrated the feasibility of using Raman spectroscopy to map cells and identify polystyrene …

Diacetone Acrylamide-Based Non-Toxic Holographic Photopolymer, Dervil Cody, Izabela Naydenova, Emilia Mihaylova

Conference Papers

A new low-toxicity diacetone acrylamide-based photopolymer is developed and characterized. The environmentally-compatible photopolymer has been modified with the inclusion of glycerol. The incorporation of glycerol results in a uniform maximum refractive index modulation for recording intensities in the range of 1-20 mW/cm². This may be attributed to glycerol’s nature as a plasticizer, which allows for faster diffusion of un-reacted monomer within the grating during holographic recording. An optimum recording intensity of 0.5 mW/cm² is observed for exposure energies of 20-60 mW/cm². The modified photopolymer achieves a refractive index modulation of 2.2x10^-3, with diffraction …

Modelling Two-Dimensional Photopolymer Patterns Produced With Multiple-Beam Holography, Dana Mackey, Tsvetanka Babeva, Izabela Naydenova, Vincent Toal

Conference papers

Periodic structures referred to as photonic crystals attract considerable interest due to their potential applications in areas such as nanotechnology, photonics, plasmonics, etc. Among various techniques used for their fabrication, multiple-beam holography is a promising method enabling defect-free structures to be produced in a single step over large areas.

In this paper we use a mathematical model describing photopolymerisation to simulate two-dimensional structures produced by the interference pattern of three noncoplanar beams. The holographic recording of different lattices is studied by variation of certain parameters such as beam wave vectors, time and intensity of illumination.

Real Time Shrinkage Studies In Photopolymer Films Using Holographic Interferometry, Mohesh Moothanchery, Izabela Naydenova, Viswanath Bavigadda, Suzanne Martin, Vincent Toal

Conference Papers

Polymerisation induced shrinkage is one of the main reasons why photopolymer materials are not more widely used for holographic applications. The aim of this study is to evaluate the shrinkage in an acrylamide photopolymer layer during holographic recording using holographic interferometry. Shrinkage in photopolymer layers can be measured by real time capture of holographic interferograms during holographic recording. Interferograms were captured using a CMOS camera at regular intervals. The optical path length change and hence the shrinkage were determined from the captured fringe patterns. It was observed that the photopolymer layer shrinkage is in the order of 3.5%.

Photonic Crystal Fiber Interferometer For Dew Detection, Jinesh Mathew, Yuliya Semenova, Gerald Farrell

Articles

A novel method for dew detection based on photonic crystal fiber (PCF) interferometer that operates in reflection mode is presented in this paper. The fabrication of the sensor head is simple since it only involves cleaving and fusion splicing. The sensor shows good sensitivity to dew formation with a large wavelength peak shift of the interference pattern at the onset of dew formation. The device’s response to ambient humidity and temperature are also studied and reported in this paper. From our experiment it is also concluded that by attaching a thermoelectric cooler with temperature feedback, the sensor head demonstrated can …

The Effect Of Participating In Continuing Optometric Education: A Pilot Study, Claire E. Mcdonnell, Martina Crehan

Other

Purpose: To determine whether participation in two different post graduate optometry workshops resulted in a change in practice for the participants, in their subsequent practice.

Methods: 38 optometrists, who had attended a continuing professional development (CPD) workshop on punctal plugs and lacrimal syringing, were surveyed by email and telephone, between four and thirteen months post workshop, to ascertain if they had made a change to their practice. A second group of 32 optometrists, who had attended a continuing education and training (CET) workshop on binocular vision, were surveyed by email, telephone and postal mail between six and nine months post …

New Non-Toxic Holographic Photopolymer Material, Dervil Cody, Izabela Naydenova, Emilia Mihaylova

Articles

There is an increasing need for environmentally friendly holographic recording materials which can be produced in bulk with little risk to the health of workers in manufacturing. This is why the development of non-toxic photopolymer materials is crucial, and has attracted attention in recent years. Composition and preliminary characterization of a new non-toxic photopolymer material are presented. It operates well at a range of spatial frequencies, and achieves diffraction efficiencies and refractive index modulation comparable to the known acrylamide-based photopolymers.