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- Holography (20)
- Photopolymer (15)
- HOE (8)
- Photopolymers (7)
- Holographic optical elements (6)
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- Interferometry (6)
- ESPI (5)
- Holographic grating (5)
- Shrinkage (5)
- Diffraction gratings (4)
- Vibrations (4)
- Acrylamide (3)
- Acrylamide based photopolymer (3)
- Diffraction (3)
- Mode analysis (3)
- Shearing interferometry (3)
- Wavefront sensing (3)
- Analog holographic wavefront sensor (2)
- ESPSI (2)
- Holographic recording materials (2)
- Reflection hologram (2)
- Surface relief gratings (2)
- Acrylamide-based photopolymer (1)
- Adaptive optics (1)
- Adhesion (1)
- Atomic force microscopy (1)
- Au Nanoparticle (1)
- Bacteria (1)
- Bayfol (1)
- Biospeckle and speckle correlation (1)
Articles 1 - 30 of 52
Full-Text Articles in Physics
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.
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 …
Development Of Holographic Optical Elements For Use In Wound Monitoring, Pamela Stoeva, Tatsiana Mikulchyk, Brian Rogers, M. Oubaha, Suzanne Martin, Dervil Cody, M.A. Ferrara, G. Coppola, Izabela Naydenova
Development Of Holographic Optical Elements For Use In Wound Monitoring, Pamela Stoeva, Tatsiana Mikulchyk, Brian Rogers, M. Oubaha, Suzanne Martin, Dervil Cody, M.A. Ferrara, G. Coppola, Izabela Naydenova
Conference Papers
Wounds that fail to heal impact the quality of life of 2.5 % of the total population. The costs of chronic wound care will reach $15–22 billion by 2024. These alarming statistics reveal the financial strain for both the medical industry and society. A solution can be found in compact and accessible sensors that offer real-time analysis of the wound site, facilitating continuous monitoring and immediate treatment, if required. Benefits of these sensors include reduction of cost and can extend the reach of healthcare to remote areas. The progression of a wound site can be closely monitored with holographic optical …
Fabrication And Characterisation Of Large Area, Uniform And Controllable Surface Relief Patterns In Photopolymer Material, Owen Kearney, Izabela Naydenova
Fabrication And Characterisation Of Large Area, Uniform And Controllable Surface Relief Patterns In Photopolymer Material, Owen Kearney, Izabela Naydenova
Conference Papers
As the risk of antibiotic resistant pathogens increases, development of convenient point of care devices is essential. Such devices would help avoid infection – ensure cleanliness of environments and assist in bacteria analysis. The ultimate aim of the research presented here is to develop a compact, cost effective, easy to use optical device which is capable of detecting and quantifying bacteria in an aqueous sample. The surface relief patterns have a dual role, they provide a diffracted light signal, and control the adhesion of the bacteria to the surface. The strength of the diffracted signal is expected to provide a …
The Development Of Optomechanical Sensors—Integrating Diffractive Optical Structures For Enhanced Sensitivity, Faolan Radford Mcgovern, Aleksandra Hernik, Catherine M. Grogan, George Amarandei, Izabela Naydenova
The Development Of Optomechanical Sensors—Integrating Diffractive Optical Structures For Enhanced Sensitivity, Faolan Radford Mcgovern, Aleksandra Hernik, Catherine M. Grogan, George Amarandei, Izabela Naydenova
Conference Papers
The term optomechanical sensors describes devices based on coupling the optical and mechanical sensing principles. The presence of a target analyte leads to a mechanical change, which, in turn, determines an alteration in the light propagation. Having higher sensitivity in comparison with the individual technologies upon which they are based, the optomechanical devices are used in biosensing, humidity, temperature, and gases detection. This perspective focuses on a particular class, namely on devices based on diffractive optical structures (DOS). Many configurations have been developed, including cantilever- and MEMS-type devices, fiber Bragg grating sensors, and cavity optomechanical sensing devices. These state-of-the-art sensors …
Design And Fabrication Of Volume Holographic Optical Couplers For A Range Of Non-Normal Incidence Angles, Dipanjan Chakraborty, Rosen Georgiev, Sinead Aspell, Izabela Naydenova, Suzanne Martin
Design And Fabrication Of Volume Holographic Optical Couplers For A Range Of Non-Normal Incidence Angles, Dipanjan Chakraborty, Rosen Georgiev, Sinead Aspell, Izabela Naydenova, Suzanne Martin
Conference Papers
A theoretical model has previously been developed to calculate the holographic recording beam angles required in air (at any recording wavelength) to produce a Volume Holographic Optical Element (VHOE) for operation as a coupler for different input and output angles. In this paper, the experimental study is extended to further validate the VHOE coupler design and fabrication approach for additional incident beam angles, comparing -40° -45° and -50° (in air). The output angle for each VHOE is +45° within the medium and the coupler operational wavelength is 633nm. Holographic recording in Bayfol HX 200 photopolymer at 532nm is used to …
Modelling Spherical Aberration Detection In An Analog Holographic Wavefront Sensor, Emma Branigan, Suzanne Martin, Matthew Sheehan, Kevin Murphy
Modelling Spherical Aberration Detection In An Analog Holographic Wavefront Sensor, Emma Branigan, Suzanne Martin, Matthew Sheehan, Kevin Murphy
Conference Papers
The analog holographic wavefront sensor (AHWFS) is a simple and robust solution to wavefront sensing in turbulent environments. Here, the ability of a photopolymer based AHWFS to detect refractively generated spherical aberration is modelled and verified.
Direct Multiplexing Of Low Order Aberration Modes In A Photopolymerbased Holographic Element For Analog Holographic Wavefront Sensing, Emma Branigan, Suzanne Martin, Matthew Sheehan, Kevin Murphy
Direct Multiplexing Of Low Order Aberration Modes In A Photopolymerbased Holographic Element For Analog Holographic Wavefront Sensing, Emma Branigan, Suzanne Martin, Matthew Sheehan, Kevin Murphy
Conference Papers
The fabrication of an analog holographic wavefront sensor, capable of detecting the low order defocus aberration, was achieved in an acrylamide-based photopolymer. While other implementations of holographic wavefront sensors have been carried out digitally, this process utilises a recording setup consisting only of conventional refractive elements so the cost and complexity of holographic optical element (HOE) production could be much reduced. A pair of diffraction spots, corresponding to a maximum and minimum amount of defocus, were spatially separated in the detector plane by multiplexing two HOEs with different carrier spatial frequencies. For each wavefront with a known aberration that was …
Optimisation Of The Performance Of Holographic Beam-Shaping Diffractive Diffusers Through Refinement Of The Recording Process, Cara Jones, Suzanne Martin, Sanjay Keshri, Dervil Cody, Kevin Murphy
Optimisation Of The Performance Of Holographic Beam-Shaping Diffractive Diffusers Through Refinement Of The Recording Process, Cara Jones, Suzanne Martin, Sanjay Keshri, Dervil Cody, Kevin Murphy
Conference Papers
Optical diffusers have uses in laser applications and machine vision. Typical fabrication at a commercial level requires master production and the stamping/copying of individual elements at scale. This expensive, indirect process inhibits custom diffusers at reasonable cost. Previously the authors published a novel, direct, single beam method of recording customizable and controllable volume holographic diffusers by manipulating laser speckle and recording the pattern in photopolymer. This method allows for beam-shaping to produce diffusion patterns of various sizes and shapes. In this work, the direct method of recording controllable holographic diffusers is refined to improve diffuser performance (i.e., a decrease in …
Development Of Photopolymer Material With Improved Dynamic Range And Sensitivity, Brian Rogers, Izabela Naydenova, Suzanne Martin
Development Of Photopolymer Material With Improved Dynamic Range And Sensitivity, Brian Rogers, Izabela Naydenova, Suzanne Martin
Conference Papers
In this study the effect of the concentration of acrylamide and the influence of different initiators in a photopolymer composition for holographic recording of diffraction gratings is investigated. Light manipulating Holographic Optical Elements (HOEs) have a number of characteristics which can be optimised for different roles. However, at the core of these devices is the refractive index modulation that has been created in the material during recording. Typically higher refractive index modulation will enable greater diffraction efficiency. Solar concentrating HOEs can particularly benefit from material that experiences higher refractive index modulation. For a solar concentrator to have a high acceptance …
Study Of The Effect Of Magnetic Nanoparticles On The Hologram Recording Capability Of Photopolymer Nanocomposite For Development Of Holographic Sensor/Actuator, Muhammad Irfan, Suzanne Martin, Izabela Naydenova
Study Of The Effect Of Magnetic Nanoparticles On The Hologram Recording Capability Of Photopolymer Nanocomposite For Development Of Holographic Sensor/Actuator, Muhammad Irfan, Suzanne Martin, Izabela Naydenova
Conference Papers
Photopolymer nanocomposite materials utilising nanoparticles of varied refractive index are one of the most attractive materials for holography due to their tuneable properties. The preparation of the photopolymer nanocomposites can involve mixing a stable colloidal suspension in the photopolymer solution or printing of the nanoparticle colloidal suspension on top of a dried photopolymer layer. By following the first approach in this study a novel photopolymer nanocomposite material is prepared for holographic recording. It consists of N-isopropylacrylamide (NIPA)-based photopolymer as a host and iron oxide magnetic nanoparticles as nanodopant. The methodology of the photopolymer nanocomposite material preparation is explained in detail. …
Mode Transition In Conventional Step-Index Optical Fibers, Xiaokang Lian, Gerald Farrell, Qiang Wu, Wei Han, Fangfang Wei, Yuliya Semenova
Mode Transition In Conventional Step-Index Optical Fibers, Xiaokang Lian, Gerald Farrell, Qiang Wu, Wei Han, Fangfang Wei, Yuliya Semenova
Conference Papers
The discrete self-imaging effect reveals the distinct properties of cladding modes with core modes in step-index optical fibers, as was shown in our previous work [1], where only the linearly polarized LP0n modes were studied. In this paper, the dispersion diagram of the first 17 vector modes (TE0n, TM0n, HEmn and EHmn) and the related first 9 LPmn modes are calculated by both the full-vector finite element method and the graphical method with a three-layer step-index optical fiber model. The cladding modes distributions and the transitions between the core and cladding modes are analyzed. The results of this work are …
Sensing Of Multiple Parameters With Whispering Gallery Mode Optical Fiber Micro-Resonators, Arun Kumar Mallik Dr, Vishnan Kavungal, Gerald Farrell, Yuliya Semenova
Sensing Of Multiple Parameters With Whispering Gallery Mode Optical Fiber Micro-Resonators, Arun Kumar Mallik Dr, Vishnan Kavungal, Gerald Farrell, Yuliya Semenova
Conference Papers
Monitoring of multiple physical parameters, such as humidity, temperature, strain, concentrations of certain chemicals or gases in various environments is of great importance in many industrial applications both for minimizing adverse effects on human health as well as for maintaining production levels and quality of products. In this paper we demonstrate two different approaches to the design of multi-parametric sensors using coupled whispering gallery mode (WGM) optical fiber micro-resonators. In the first approach, a small array of micro-resonators is coupled to a single fiber taper, while in the second approach each of the micro-resonators within an array is coupled to …
Theoretical Analysis Of A Volume Holographic Lens Using Matlab, Sanjay Keshri, Kevin Murphy, Izabela Naydenova, Suzanne Martin
Theoretical Analysis Of A Volume Holographic Lens Using Matlab, Sanjay Keshri, Kevin Murphy, Izabela Naydenova, Suzanne Martin
Conference Papers
Volume holographic lenses have great potential for different types of applications requiring light redirection and beam shaping such as solar light collection and LED light management. For lighting applications using LEDs, it is essential to make a highly efficient optical element to be placed in front of the LED in order to decrease energy losses. For that reason, a careful theoretical analysis of the properties and operation regime of the lens must be carried out at the design stage. The characteristics of focusing Holographic Optical Elements (HOE) depend on many factors including their thickness, spatial frequency, the angular range of …
Investigation Of Temperature Response Of Photopolymer Material Used For Holographic Sensor, Muhammad Irfan, Tatsiana Mikulchyk, Suzanne Martin, Izabela Naydenova
Investigation Of Temperature Response Of Photopolymer Material Used For Holographic Sensor, Muhammad Irfan, Tatsiana Mikulchyk, Suzanne Martin, Izabela Naydenova
Conference Papers
Recently, functionalised photopolymer has emerged as a versatile recording material in the field of optical holography due to its novel characteristics and potential use in the development of holographic based sensors, and optical elements. This work describes the temperature response of a newly developed photopolymer, containing of a monomer Nisopropylacrylamide (NIPA) which under photopolymerisation forms a temperature sensitive polymer - Poly(Nisopropylacrylamide) (PNIPA). The photonic sensor was developed by holographic recording of volume phase transmission gratings in a self-processing NIPA-based polymer with a 532 nm laser beam. A 633 nm probe beam was used to monitor real time diffraction efficiency (DE) …
Compact Holographic Optical Element-Based Electronic Speckle Pattern Interferometer For Rotation And Vibration Measurements, Viswanath Bavigadda, Mohesh Moothanchery, Manojit Pramanik, Emilia Mihaylova, Vincent Toal
Compact Holographic Optical Element-Based Electronic Speckle Pattern Interferometer For Rotation And Vibration Measurements, Viswanath Bavigadda, Mohesh Moothanchery, Manojit Pramanik, Emilia Mihaylova, Vincent Toal
Conference Papers
An out-of-plane sensitive electronic speckle pattern interferometer (ESPI) using holographic optical elements (HOEs) for studying rotations and vibrations is presented. Phase stepping is implemented by modulating the wavelength of the laser diode in a path length imbalanced interferometer. The time average ESPI method is used for vibration measurements. Some factors influencing the measurements accuracy are reported. Some advantages and limitations of the system are discussed.
Effect Of Monomer Diffusion On Photoinduced Shrinkage In Photopolymer Layers Determined By Electronic Speckle Pattern Interferometry, Mohesh Moothanchery, Manojit Pramanik, Vincent Toal, Izabela Naydenova
Effect Of Monomer Diffusion On Photoinduced Shrinkage In Photopolymer Layers Determined By Electronic Speckle Pattern Interferometry, Mohesh Moothanchery, Manojit Pramanik, Vincent Toal, Izabela Naydenova
Conference Papers
The aim of this study is to determine the effect of monomer diffusion on the photoinduced shrinkage profile in acrylamide based photopolymer layers during holographic recording. Using phase shifting electronic speckle pattern interferometry the displacement at each pixel in the image of the layer is measured. The complete displacement profile of the layer was obtained using phase shifting technique. We observed a reduction in shrinkage as a result of monomer diffusion from unexposed regions of holographic exposure. As a result of diffusion the maximum shrinkage was reduced by 26 % from 7.18μm to 5.28μm in a photopolymer layer of thickness160 …
Quantitative Measurement Of Displacement In Photopolymer Layers During Holographic Recording Using Phase Shifting Electronic Speckle Pattern Interferometry, Mohesh Moothanchery, Viswanath Bavigadda, Paul Kumar Upputturi, Manojit Pramanik, Vincent Toal, Izabela Naydenova
Quantitative Measurement Of Displacement In Photopolymer Layers During Holographic Recording Using Phase Shifting Electronic Speckle Pattern Interferometry, Mohesh Moothanchery, Viswanath Bavigadda, Paul Kumar Upputturi, Manojit Pramanik, Vincent Toal, Izabela Naydenova
Conference Papers
The aim of this study is to determine the displacement profile due to shrinkage in acrylamide-based photopolymer layer during holographic recording. Using phase shifting electronic speckle pattern interferometry the displacement at each pixel in the image of the object is measured by phase shifting technique so that a complete displacement profile of the object can be obtained. It was observed that the displacement profile is Gaussian and resembles to the profile of the recording beam. We observed an increase in shrinkage from 2 μm at 20 seconds of recording to 7.5 μm after 120 seconds of recording. The technique allows …
Design And Study Of Acrylamide-Based Photopolymer Holographic Optical Elements For Solar Application, Hoda Akbari, Izabela Naydenova, Manus Kennedy, John Doran, Suzanne Martin
Design And Study Of Acrylamide-Based Photopolymer Holographic Optical Elements For Solar Application, Hoda Akbari, Izabela Naydenova, Manus Kennedy, John Doran, Suzanne Martin
Conference Papers
Abstract: Solar concentrators can be used to reduce the cost of photovoltaic electrical power generation by collecting incident solar radiation from a given aperture area and transmitting the energy to a reduced area. In doing so, the overall cost of power (Wp) can be reduced as less area of photovoltaic is required. This paper will discuss Holographic Solar Concentrators fabricated in an acrylamide photopolymer , describing the optical recording process and showing how the fabricated HOE’s can be used in solar concentrator devices. Preliminary lifetime studies are also discussed.
Diacetone Acrylamide-Based Non-Toxic Holographic Photopolymer, Dervil Cody, Izabela Naydenova, Emilia Mihaylova
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 …
Real Time Shrinkage Studies In Photopolymer Films Using Holographic Interferometry, Mohesh Moothanchery, Izabela Naydenova, Viswanath Bavigadda, Suzanne Martin, Vincent Toal
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%.
Fluorescence Emission Study Of Cdse/Zns Quantum Dot And Au Nanoparticles Composite For Application In Quantum Dot Solar Concentrators, Subhash Chandra, John Doran, Manus Kennedy, S Mccormack, A Chatten
Fluorescence Emission Study Of Cdse/Zns Quantum Dot And Au Nanoparticles Composite For Application In Quantum Dot Solar Concentrators, Subhash Chandra, John Doran, Manus Kennedy, S Mccormack, A Chatten
Conference Papers
Fluorescence of core shell (CdSe/ZnS) quantum dots (QDs) and Au nanoparticles (NPs) composite has been studied for application in quantum dot solar concentrators (QDSC). We conclude two points from the particular QD/Au NP composite studied. One; for the particular Au NPs concentration, the relative fluorescence emission enhancement increases with decreasing QD concentration. Second; the enhancement is more pronounced for the Au nanoparticles whose surface plasmon resonance wavelength overlaps with the absorption peak of QDs. The fundamental concept that could describe the change in fluorescence emission of QDs in the presence of Au NPs is the locally enhanced electromagnetic field induced …
Nanoparticle Doped Photopolymer With Reduced Shrinkage For Holographic Recording, Mohesh Moothanchery, Svetlana Mintova, Izabela Naydenova, Vincent Toal
Nanoparticle Doped Photopolymer With Reduced Shrinkage For Holographic Recording, Mohesh Moothanchery, Svetlana Mintova, Izabela Naydenova, Vincent Toal
Conference Papers
We demonstrate holographic recording with Si-MFI zeolite doped acrylamide based photopolymerfilm. The influence of silicate nanoparticles on photopolymer shrinkage has been studied and compared withshrinkage in undoped photopolymer layers The shrinkage of the material (1.03%) is significantly lower forrecording in Si-MFI zeolite nanoparticle doped samples than for undoped layers (1.77%).
Design And Fabrication Of Holographic Optical Elements For Applications In Electronic Speckle Pattern Interferometry And Laser Doppler Vibrometry, Viswanath Bavigadda, Emilia Mihaylova, Raghavendra Jallapuram, Vincent Toal
Design And Fabrication Of Holographic Optical Elements For Applications In Electronic Speckle Pattern Interferometry And Laser Doppler Vibrometry, Viswanath Bavigadda, Emilia Mihaylova, Raghavendra Jallapuram, Vincent Toal
Conference Papers
An important area of application of holographic optical elements (HOEs) is in optical and electronic speckle pattern interferometry. The design, fabrication and characterization of holographic optical elements (HOEs) for electronic speckle pattern interferometry are presented. Reflection HOEs (RHOEs) were fabricated for use in electronic speckle pattern interferometers (ESPI) and laser Doppler vibrometers (LDV). The HOE-based interferometer is sensitive to out-of-plane displacements only. The results obtained are promising for future applications of the system for modal analysis.
Optical Properties Of Photopolymerisable Nanocomposites Containing Zeolite Nanoparticles, Izabela Naydenova, Tzvetanka Babeva, Elsa Leite, Nitesh Pandey, Temenujka Yovcheva, Svetlana Mintova, Vincent Toal
Optical Properties Of Photopolymerisable Nanocomposites Containing Zeolite Nanoparticles, Izabela Naydenova, Tzvetanka Babeva, Elsa Leite, Nitesh Pandey, Temenujka Yovcheva, Svetlana Mintova, Vincent Toal
Conference Papers
Acrylamide-based photopolymerisable nanocomposites containing three different types of nanozeolites – Si-MFI, AlPO and BEA, were studied. The influence of the porous nanoparticles on the average refractive index, optical scattering, holographic recording properties and shrinkage were characterised.
Holographic Recording In Charged Photopolymerisable Nanocomposites, Temenujka Yovcheva, Ivanka Vlaeva, Simeon Sainov, Izabela Naydenova, Vincent Toal, Svetlana Mintova
Holographic Recording In Charged Photopolymerisable Nanocomposites, Temenujka Yovcheva, Ivanka Vlaeva, Simeon Sainov, Izabela Naydenova, Vincent Toal, Svetlana Mintova
Conference Papers
Self – processing photopolymers have a large number of different applications due to their versatile properties as holographic recording materials. A significant effort has been directed towards the development of photopolymers for holographic data storage [1, 2], holographic sensors [3], holographic optical elements [4] and display holograms [5]. The Centre for Industrial and Engineering Optics has been developing acrylamide based photopolymers for the last decade [6-8]. The main parameters requiring improvement in these types of photopolymers are their dynamic range and their mechanical stability during the holographic recording. Recently we have successfully used zeolite nanoparticles as dopants in order to …
A Single Beam Data Writing Process For Holographic Data Storage, Suzanne Martin, Denis Bade, Izabela Naydenova, Vincent Toal
A Single Beam Data Writing Process For Holographic Data Storage, Suzanne Martin, Denis Bade, Izabela Naydenova, Vincent Toal
Conference Papers
A concept is described that could allow Holographic Data Storage with angular multiplexing using, uniquely, only one data writing beam; pre-recorded ‘seed’ gratings are illuminated with one writing beam in order to produce a data grating.
Out-Of-Plane Vibration Analysis With A Transmission Holographic Optical Element Based Electronic Speckle Pattern Interferometer, Viswanath Bavigadda, Vincent Toal, Raghavendra Jallapuram, Emilia Mihaylova
Out-Of-Plane Vibration Analysis With A Transmission Holographic Optical Element Based Electronic Speckle Pattern Interferometer, Viswanath Bavigadda, Vincent Toal, Raghavendra Jallapuram, Emilia Mihaylova
Conference Papers
A simple electronic speckle pattern interferometer (ESPI) using a transmission holographic optical element (THOE) is presented. The THOE is designed to create a speckled reference beam in the interferometer. It is a transmission hologram of a diffusely transmitting glass plate A specific requirement for the fabrication of the THOEs is for them to be recorded at one wavelength at which the recording material is photosensitive and reconstructed using a near infrared laser diode which can be current modulated for phase shifting purposes. A partially reflective glass plate provides illumination of the object along the normal to its surface, ensuring that …
Ocular Microtremor Laser Speckle Metrology, Mohammed Al-Kalbani, Emilia Mihaylova, Niamh Collins, David Coakley, Gerard Boyle, Vincent Toal
Ocular Microtremor Laser Speckle Metrology, Mohammed Al-Kalbani, Emilia Mihaylova, Niamh Collins, David Coakley, Gerard Boyle, Vincent Toal
Conference Papers
Ocular Microtremor (OMT) is a continual, high frequency physiological tremor of the eye present in all subjects even when the eye is apparently at rest. OMT causes a peak to peak displacement of around 150nm-2500nm with a broadband frequency spectrum between 30Hz to 120Hz; with a peak at about 83Hz. OMT carries useful clinical information on depth of consciousness and on some neurological disorders. Nearly all quantitative clinical investigations have been based on OMT measurements using an eye contacting piezoelectric probe which has low clinical acceptability. Laser speckle metrology is a candidate for a high resolution, non-contacting, compact, portable OMT …
Optical Patterning Of Photopolymerisable Materials, Kevin Trainer, Kevin Wearen, Dimana Nazarova, Izabela Naydenova, Vincent Toal
Optical Patterning Of Photopolymerisable Materials, Kevin Trainer, Kevin Wearen, Dimana Nazarova, Izabela Naydenova, Vincent Toal
Conference Papers
Holographic recording is an effective approach for photopolymer surface patterning. It has been previously utilised in acrylamide-based photopolymers and a spatial frequency limit of 200 l/mm has been observed. We report the successful inscription of submicrometer resolution patterns. The spatial frequency response has been extended to 1550 l/mm by introduction of thermal post recording treatment. Initial results from the optical patterning utilising a spatial light modulation (SLM) reveal that the amplitude of the photoinduced surface relief structures is larger in comparison to the amplitude obtained by holographic recording.