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Full-Text Articles in Physics
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 …
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. …
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) …
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 …
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%.
Hologram-Based Humidity Indicator For Domestic And Packaging Applications, Izabela Naydenova, Raghavendra Jallapuram, Vincent Toal, Suzanne Martin
Hologram-Based Humidity Indicator For Domestic And Packaging Applications, Izabela Naydenova, Raghavendra Jallapuram, Vincent Toal, Suzanne Martin
Conference Papers
A passive indicator for Relative Humidity based on a photopolymer recorded hologram has been developed. The indicator works on the principle that the wavelength reconstructed by a reflection hologram is dependent on the spacing between the fringe planes of the hologram. As the Relative Humidity changes, the hologram swells or shrinks and the apparent colour of the reconstructed image changes. The response time, operational range and reversibility of the indicator have been studied in a controlled humidity environment. Response times from less than a minute to tens of minutes depending on the holograms physical properties have been measured. Indicators with …
Two Way Diffusion Model For The Recording Mechanism In A Self-Developing Dry Acrylamide Photopolymer, Suzanne Martin, Izabela Naydenova, Raghavendra Jallapuram, Robert Howard, Vincent Toal
Two Way Diffusion Model For The Recording Mechanism In A Self-Developing Dry Acrylamide Photopolymer, Suzanne Martin, Izabela Naydenova, Raghavendra Jallapuram, Robert Howard, Vincent Toal
Conference Papers
In our most recent study [1] diffusion constants were measured in the simplified monoacrylamide version of a dry acrylamide based photopolymer holographic recording material developed in the Centre for Industrial and Engineering Optics. In this paper we report diffusion constants for the commonly used photopolymer formulation, which also contains the crosslinker bisacrylamide. A physical model for the recording mechanism is proposed which explains the two way diffusion observed in both systems, and is in agreement with much of the previously observed behaviour of the material, particularly in regard to dependence of diffraction efficiency growth on spatial frequency and persistence of …
A Compact Electronic Speckle Pattern Interferometry System Using A Photopolymer Reflection Holographic Optical Element, Guntaka Tulasi Sridhar Reddy, Raghavendra Jallapuram, Vincent Toal, Izabela Naydenova, Suzanne Martin, Svetlana Mintova
A Compact Electronic Speckle Pattern Interferometry System Using A Photopolymer Reflection Holographic Optical Element, Guntaka Tulasi Sridhar Reddy, Raghavendra Jallapuram, Vincent Toal, Izabela Naydenova, Suzanne Martin, Svetlana Mintova
Conference Papers
A simple and compact electronic speckle pattern interferometry system using a reflection holographic optical element is presented. The reflection holographic optical element is recorded on an acrylamide based photopolymer formulated and prepared at the Centre for Industrial & Engineering Optics. Light intensity of 40mW/cm2 with an exposure time of 60 seconds was used in fabricating the holographic optical element. The vibration mode patterns of a 4 cm diameter thin circular sheet of brass metal attached to a 4 cm diameter paper cone loud speaker are presented.
Investigation Of Polymerization Rate In An Acrylamide-Based Photopolymer Using Raman Spectroscopy, Raghavendra Jallapuram, Izabela Naydenova, Hugh Byrne, Suzanne Martin, Robert Howard, Vincent Toal
Investigation Of Polymerization Rate In An Acrylamide-Based Photopolymer Using Raman Spectroscopy, Raghavendra Jallapuram, Izabela Naydenova, Hugh Byrne, Suzanne Martin, Robert Howard, Vincent Toal
Conference Papers
Diffusion models predict that polymerization and diffusion rates are the key factors that control the dynamics and the final properties of a holographic grating recorded in a photopolymerizable material. Diffusion rates during the initial phase of holographic recording have already been studied and reported. We now report the investigation of the polymerization rate in an acrylamide-based photopolymer using Raman spectroscopy. The polymerization rate constant was estimated by monitoring the intensity of the characteristic Raman peaks at 1284 cm-1 corresponding to the bending mode of CH vinyl bond in acrylamide and 1609 cm-1 corresponding to the carbon-carbon double bond (C=C) in …
Application Of Photopolymer Holographic Gratings, Emilia Mihaylova, Izabela Naydenova, Hosam Sherif, Suzanne Martin, Vincent Toal
Application Of Photopolymer Holographic Gratings, Emilia Mihaylova, Izabela Naydenova, Hosam Sherif, Suzanne Martin, Vincent Toal
Conference Papers
Two optical set-ups for electronic speckle pattern shearing interferometry (ESPSI) using photopolymer diffractive optical elements are presented. Holographic gratings are recorded using an acrylamide based photopolymer material. Since the polymerisation process occurs during recording, the holograms are produced without any development or processing. In both ESPSI systems the photopolymer gratings are used to shear the image. In the first ESPSI system only one grating is used in combination with a sheet of ground glass. The distance between the grating and the ground glass can be used to control the amount of the shear. The sheared images on the ground glass …
Investigation Of The Photoinduced Surface Relief Modulation In Acrylamide-Based Photopolymer, Izabela Naydenova, Emilia Mihaylova, Suzanne Martin, Vincent Toal
Investigation Of The Photoinduced Surface Relief Modulation In Acrylamide-Based Photopolymer, Izabela Naydenova, Emilia Mihaylova, Suzanne Martin, Vincent Toal
Conference Papers
A surface relief diffraction grating is inscribed in acrylamide photopolymer by holographic recording with spatial frequency below 300 l/mm. The periodic surface modulation appears in addition to a volume phase holographic grating. Due to the nature of the presented photopolymerisable material the gratings are induced by light only and no post-processing is required. An investigation of the dependance of the amplitude of the photoinduced relief modulation on spatial frequency of recording and on sample thickness has been carried out utilising white light interferometry. A model of the mechanism of surface relief formation is proposed on the basis of the measured …
Spatial Frequency Response Of Acrylamide Based Holographic Photopolymer, Raghavendra Jallapuram, Izabela Naydenova, Vincent Toal, Suzanne Martin, Robert Howard
Spatial Frequency Response Of Acrylamide Based Holographic Photopolymer, Raghavendra Jallapuram, Izabela Naydenova, Vincent Toal, Suzanne Martin, Robert Howard
Conference Papers
It has been shown that photopolymers are useful in holographic optical elements [1] and holographic interferometry [2]. However, the list of potential applications increases greatly if reflection holography is possible. Reflection holography requires a material that has the potential to record high spatial frequencies. Here we studied the spatial frequency response of an acrylamide based dye sensitized holographic photopolymer. We have investigated the effect of molecular weight of the binder and concentration of crosslinking monomer on diffusion using real time monitoring of the holographic grating formation. The effect of uniform pre-exposure on diffusion was also investigated. We have also demonstrated …
Application Of A Photopolymer Material In Speckle Pattern Shearing Interferometry, Emilia Mihaylova, Izabela Naydenova, Suzanne Martin, Vincent Toal
Application Of A Photopolymer Material In Speckle Pattern Shearing Interferometry, Emilia Mihaylova, Izabela Naydenova, Suzanne Martin, Vincent Toal
Conference Papers
A new application of a photopolymer diffractive optical element in electronic speckle pattern shearing interferometer (ESPSI) is presented. In the first stage a holographic grating is recorded using an acrylamide based photopolymer material. Since the polymerisation process occurs during recording, the holograms are produced without any development or processing. In the second stage the holographic grating is used to produce the two sheared images in an ESPSI configuration. A ground glass screen following the grating serves the purpose of eliminating unwanted diffraction orders. The distance between the grating and the ground glass can be used to control the amount of …