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Full-Text Articles in Physics
Photopolymers: Beyond The Standard Approach To Photosensitisation, Izabela Naydenova, Suzanne Martin, Vincent Toal
Photopolymers: Beyond The Standard Approach To Photosensitisation, Izabela Naydenova, Suzanne Martin, Vincent Toal
Articles
A photopolymerizable material for use in the visible normally consists of a dye sensitizer, a free radical generator, monomer/monomers and, optionally, a binder, and is prepared usually as a dry or liquid film. Upon illumination with light of appropriate wavelength, a photopolymerisation reaction is triggered, leading to a change in the film’s refractive index. Because the presence of the dye is essential, the film is usually made sensitive to light during its preparation. Here we separate the film preparation and the sensitisation processes. In this way the photopolymerisation process can be used to detect dye labelled analytes, providing an alternative …
Scan-Based Near-Field Acoustical Holography On Partially Correlated Sources, Michael D. Gardner
Scan-Based Near-Field Acoustical Holography On Partially Correlated Sources, Michael D. Gardner
Theses and Dissertations
Scan-based near-field acoustical holography (NAH) is applied to partially correlated sources. Partial field decomposition via the virtual coherence method is used to implement the scan-based NAH. The background and theory of these methods are developed. Multiple stationary reference microphones are required for the partial field decomposition. Guidelines for reference microphone placement in the literature thus far have been limited. Improved guidelines for reference microphones are given after the results of two sets of experiments. The first set involves discrete, partially correlated sources, both physical and numerical. The second set of experiments is strictly numerical and involves continuous sources. Fewer microphones …
Characterisation Of The Humidity And Temperature Responses Of A Reflection Hologram Recorded In Acrylamide-Based Photopolymer, Izabela Naydenova, Raghavendra Jallapuram, Vincent Toal, Suzanne Martin
Characterisation Of The Humidity And Temperature Responses Of A Reflection Hologram Recorded In Acrylamide-Based Photopolymer, Izabela Naydenova, Raghavendra Jallapuram, Vincent Toal, Suzanne Martin
Articles
The humidity and temperature responses of a reflection hologram recorded in a self-processing photopolymer layer have been characterised by measurement of the position of the maximum intensity in the spectral response of the hologram. It has been demonstrated that such a hologram can be used for indication of the relative humidity (RH) in a specific temperature range. The operational range and reversibility of the holograms have been characterised in a controlled humidity and temperature environment. The humidity studies were carried out in the range from 10 to 80% RH and the temperature range under study was 15 – 50 ºC.
Optical And Holographic Characteristics Of Photopolymer Layers, Temenujka Yovcheva, Izabela Naydenova, Ivanka Vlaeva, Suzanne Martin, Vincent Toal, Simeon Sainov
Optical And Holographic Characteristics Of Photopolymer Layers, Temenujka Yovcheva, Izabela Naydenova, Ivanka Vlaeva, Suzanne Martin, Vincent Toal, Simeon Sainov
Articles
In the present work the optical and holographic characteristics of acrylamide-based photopolymer layers are studied. For the first time the refractive index change of a liquid acrylamide photopolymer due to exposure at 532 nm is obtained using a critical angle laser micro-refractometer. The 30 mm thick solid photopolymer films are prepared by casting on glass substrates. Bragg holographic gratings with spatial frequencies of 710 mm-1, 1050 mm-1 and 1600 mm-1 are recorded using a diode laser operating at 532 nm wavelength. The diffraction efficiency dependence on the exposure energy is investigated. The obtained results are compared with the Stetson holographic …
Holographic Liquid Crystal Devices, Kotakonda Pavani
Holographic Liquid Crystal Devices, Kotakonda Pavani
Doctoral
Liquid crystals have become natural candidates for use in electro-optic devices for their ability to change the orientation of the director with the application of an electric field, and exhibiting large range of refractive index. The aim of the work presented in this thesis is to fabricate liquid crystal optoelectronic devices such as electrically switchable liquid crystal diffraction gratings and polarization rotators by exploiting the holographic surface relief effect in photopolymer and by developing novel polymer dispersed liquid crystals (PDLCs). Alignment of liquid crystals is commercially achieved by creating grooves on a conducting layer such as polyimide or indium tin …
Recent And Emerging Applications Of Holographic Photopolymers And Nanocomposites, Izabela Naydenova, Pavani Kotakonda, Raghavendra Jallapuram, Tsvetanka Babeva, Denis Bade, Suzanne Martin, Vincent Toal, Svetlana Mintova
Recent And Emerging Applications Of Holographic Photopolymers And Nanocomposites, Izabela Naydenova, Pavani Kotakonda, Raghavendra Jallapuram, Tsvetanka Babeva, Denis Bade, Suzanne Martin, Vincent Toal, Svetlana Mintova
Conference Papers
Sensing applications of holograms may be based on effects such as change in the spacing of the recorded fringes in a holographic diffraction grating in the presence of an analyte so that the direction of the diffracted laser light changes, or, in the case of a white light reflection grating, the wavelength of the diffracted light changes. An example is a reflection grating which swells in the presence of atmospheric moisture to indicate relative humidity by a change is the colour of the diffracted light. These devices make use of the photopolymer’s ability to absorb moisture. In a more versatile …