A5068249599- Digital Holography and Microscopy
- Advanced Optical Imaging Technologies
- Spectroscopy Techniques in Biomedical and Chemical Research
- Image Processing Techniques and Applications
- Spectroscopy and Chemometric Analyses
- Advanced Vision and Imaging
- Optical measurement and interference techniques
- Mathematical Analysis and Transform Methods
- Chaos-based Image/Signal Encryption
- Image and Signal Denoising Methods
- Optical Polarization and Ellipsometry
- Optical Coherence Tomography Applications
- Advanced X-ray Imaging Techniques
- Orbital Angular Momentum in Optics
- Digital Filter Design and Implementation
- Optical and Acousto-Optic Technologies
- Advanced Measurement and Metrology Techniques
- Advanced Steganography and Watermarking Techniques
- Advanced Image Processing Techniques
- Thermography and Photoacoustic Techniques
- Advanced Fluorescence Microscopy Techniques
- Microfluidic and Bio-sensing Technologies
- Mathematical Dynamics and Fractals
- Photonic and Optical Devices
- Optical Imaging and Spectroscopy Techniques
National University of Ireland, Maynooth
2016-2025
Bremen Institute for Applied Beam Technology
2020
National University of Ireland
2005-2019
Kildare Education Centre
2016-2018
Bryan College
2016
University College Dublin
2003-2011
Technische Universität Ilmenau
2011
Universidad Nacional Autónoma de México
2011
TU Wien
2007
University of Connecticut
2007
A number of methods have recently been proposed in the literature for encryption two-dimensional information by use optical systems based on fractional Fourier transform. Typically, these require random phase screen keys decrypting data, which must be stored at receiver and carefully aligned with received encrypted data. new technique a shifting, or jigsaw, algorithm is proposed. This method does not keys. The image juxtaposition sections domains. has compared existing shows comparable...
Comparison of Raman spectra recorded from fresh cheek cells across ten sample substrates and five source wavelengths.
Contents1. Materials for dynamic holographic 3D display 2. Photopolymerizable nanocomposite materials applications 3. Photopolymers the recording of waveguides 4. Shrinkage in materials: photopolymers 5. Advances photorefractive and devices 6. Industrial-scale material mass production vHOEs 7. Non-imaging optics solar energy conversion 8. Data security data storage 9. Multimodal acquisition using digital holography 10.EUV SXR tomography with compact short wavelength sources 11.Holographic...
By use of matrix-based techniques it is shown how the space-bandwidth product (SBP) a signal, as indicated by location signal energy in Wigner distribution function, can be tracked through any quadratic-phase optical system whose operation described linear canonical transform. Then, applying regular uniform sampling criteria imposed SBP and linking explicitly to decomposition matrix system, numerical algorithms (employing interpolation decimation), which exhibit both invertibility...
The linear canonical transform (LCT) describes the effect of any quadratic phase system (QPS) on an input optical wave field. Special cases LCT include fractional Fourier (FRT), (FT), and Fresnel (FST) describing free-space propagation. Currently there are numerous efficient algorithms used (for purposes numerical simulation in area signal processing) to calculate discrete FT, FRT, FST. All these based use fast (FFT). In this paper we develop theory for (DLCT), which is what (DFT) FT. We...
We present a digital signal processing technique that reduces the speckle content in reconstructed holograms. The method is based on sequential sampling of discrete Fourier transform image field. Speckle reduction achieved at expense reduced intensity and resolution, but this trade-off shown to be greatly superior imposed by traditional mean median filtering techniques. In particular, we show can half with no loss resolution (according standard definitions both metrics).
We examine some fundamental theoretical limits on the ability of practical digital holography (DH) systems to resolve detail in an image. Unlike conventional diffraction-limited imaging systems, where a projected image limiting aperture is used define system performance, there are at least three major effects that determine performance DH system: (i) The spacing between adjacent pixels CCD, (ii) averaging effect introduced by finite size these pixels, and (iii) extent camera face itself....
This paper presents an extended viewing angle holographic display for reconstruction of real world objects in which the capture and systems are decoupled. is achieved by employing multiple tilted spatial light modulators (SLMs) arranged a circular configuration. In order to prove proper visual perception images Wigner distribution function employed. We describe both system using single static camera with rotating object utilizing six SLMs. The experimental results based on computer generated...
The algorithm enhances Savitzky–Golay smoothing with maximum likelihood estimation, which outperforms traditional in terms of peak fidelity and SNR.
When a digital hologram is reconstructed, only points located at the reconstruction distance are in focus. We have developed novel technique for creating an in-focus image of macroscopic objects encoded hologram. This extended focused created by combining numerical reconstructions with depth information extracted using our depth-from-focus algorithm. To knowledge, this first that creates images holograms encoding objects. present results containing low- and high-contrast
Raman spectroscopy is a powerful diagnostic tool in biomedical science, whereby different disease groups can be classified based on subtle differences the cell or tissue spectra. A key component classification of spectra application multi-variate statistical models. However, scattering weak process, resulting trade-off between acquisition times and signal-to-noise ratios, which has limited its more widespread adoption as clinical tool. Typically denoising applied to spectrum from biological...
We analyze optical encryption systems using the techniques of conventional cryptography. All block algorithms are vulnerable to attack, and often they employ secure modes operation as one way increase security. introduce concept results in context known attacks. consider only system "double random phase encoding," which forms basis for a large number encryption, watermarking, multiplexing systems. all attacks proposed date particular scenario. mathematical themselves do not additional...
This paper presents the full technology chain supporting wide angle digital holographic television from capture of real world objects/scenes to display with an extended viewing angle. The data are captured multiple CCD cameras located around object. system is based on tilted spatial light modulators (SLMs) arranged in a circular configuration. capture-display linked by processing module, which allows for significant decoupling and systems. presented experimental results, reconstruction...
Abstract Rapid label‐free spectroscopy of biological and chemical specimen via molecular vibration through means broadband coherent anti‐Stokes Raman scattering (B‐CARS) could serve as a basis for robust diagnostic platform wide range applications. A limiting factor CARS is the presence non‐resonant background (NRB) signal, endemic to technique. This multiplicative with chemically resonant meaning perturbation it generates cannot be accounted simply. Although several numerical approaches...
A number of methods have been recently proposed in the literature for encryption 2-D information using optical systems based on linear transforms, i.e., Fourier (FT), fractional (FRT), Fresnel (FST), and canonical transform (LCT). We propose examine two schemes (FST) use random phase screens jigsaw transforms (JT). The strength robustness level various techniques are examined with respect to blind decryption. These compared similar FRT- LCT-based methods. Optical implementations also...
View-reconstruction and display is an important part of many applications in digital holography such as computer vision microscopy. Thus far, this has been offline procedure for megapixel sized holograms. This paper introduces implementation real-time view-reconstruction using programmable graphics hardware. The theory Fresnel-based introduced, after which stream programming presented. Two different fast Fourier transform (FFT)-based reconstruction methods are implemented, well two FFT...
Digital holography is an imaging technique that enables recovery of topographic 3D information about object under investigation. In digital holography, interference pattern recorded on a camera. Therefore, quantization the hologram integral part process. We study influence error in holograms fidelity both intensity and phase reconstructed image. limit our analysis to case lensless Fourier off-axis holograms. derive theoretical model predict effect noise we validate this using experimental...
The application of digital holography as a viable solution to 3D capture and display technology is examined. A review the current state field presented in which some major challenges involved holographic are highlighted. These include (i) removal DC conjugate image terms, features recording process, (ii) reduction speckle noise, characteristic coherent imaging (iii) increasing angular range perspective holograms (iv) replaying captured and/or processed using spatial light modulators. Each...
Digital holographic systems are a class of two step, opto-numerical, pseudo-three-dimensional imaging techniques. The role the digital camera in limiting resolution and field view reconstructed image, interaction these limits with general optical system is poorly understood. linear canonical transform describes any consisting lenses and/or free space unified manner. Expressions derived using this parametrised terms parameters system, as well those camera: aperture size, pixel size pitch. We...
This paper presents a novel method of multi-spatial light modulator (SLM) holographic image display that enables wide angle reconstruction images real world objects. The data are delivered by means digital holography. capture and systems arranged in circular configuration. In order to support the proper information flow between multi-sensor multi-SLM we perform analysis using Wigner distribution function. We also consider mismatch configurations as well visual perception displayed image....