We discuss the symmetry properties of the Ambiguity Function. Next, we use it as a design tool for increasing the depth of field of imaging systems. We present a family of anti-symmetric phase-only masks that extend the depth of field of an optical system. We compute several Optical Transfer Functions with focus errors, and we report numerical simulations of the images that can be achieved using our proposed phase-only filters.

We present the investigation of integration of Variable Focal Length (VFL) microlenses into the confocal system. VFL microlenses acting as an array of objective lenses is examined with a novel method for scanning in the axial direction presented. By variation of the focal length of the lenses the focal plane can be scanned through the sample without the mechanical movement of the sample or the objective lens, we have named this 'focal scanning'. Some of the issues related to this experiment are noted and discussed, in particular with reference to the low Numerical Aperture (NA) of the VFL microlenses available. Proposed solutions to these issues deal with the design of higher NA microlenses.

When light propagates through the atmosphere the fluctuating refractive index caused by temperature gradients, humidity fluctuations and the wind mixing of air cause the phase of the optical field to be corrupted. In strong turbulence, over horizontal paths or at large zenith angles, the phase aberration is converted to intensity variation (scintillation) as interference within the beam and diffraction effects produce the peaks and zeros of a speckle-like pattern. At the zeros of intensity the phase becomes indeterminate as both the real and imaginary parts of the field go to zero. The wavefront is no longer continuous but contains dislocations along lines connecting phase singularities of opposite rotation. Conventional adaptive optics techniques of wavefront sensing and wavefront reconstruction do not account for discontinuous phase functions and hence can only conjugate an averaged, continuous wavefront. We are developing an adaptive optics system that can cope with dislocations in the phase function for potential use in a line-of-sight optical communications link. Using a ferroelectric liquid crystal spatial light modulator (FLC SLM) to generate dynamic atmospheric phase screens in the laboratory, we simulate strong scintillation conditions where high densities of phase singularities exist in order to compare wavefront sensors for tolerance to scintillation and accuracy of wavefront recovery.

We propose and demonstrate a technique based on digital holography for three-dimensional (3D) object recognition. In our method, the complex wavefront of the 3D object to be recognized is recorded as a Fresnel hologram using a CCD camera. A two step numerical reconstruction process, retrieval of complex wavefront recorded on the CCD plane and propagation of wavefront to the object plane, gives a complex valued two-dimensional (2D) image, which contains information regarding the amplitude and phase of the object wavefront in a 2D plane. The encoding of 3D object information as 2D digital image enables the use of various image-processing techniques for the post processing of the data. We use a Mexican hat wavelet matched filter (WMF) to discriminate between two different objects. WMF performs wavelet transform (WT) to enhance significant features of the images and the correlation of the so obtained WT coefficients in a single step. Digital wavelet matched filtering improves the discrimination capability and results in sharper correlation peaks as compared to classical matched filtering. As compared to many of the 3D recognition techniques based on the processing of 2D perspectives, our system has lesser complexity at the implementation and operational levels.

Numerous papers have been written on the various roles the Wigner distribution function (WDF) can play in optics. The purpose of this paper is to show two applications of the WDF in the analysis, design, and simulation of optical systems. One system provides a vehicle for reducing the computational load in the numerical simulation of the propagation of optical wave fields. The WDF analysis of this system yields insight into methods that might be used in simplifying optical system simulations generally. The second system is intended for the sample-based recording of coherence functions associated with the propagated wave field produced by a three-dimensional, spatially-incoherent object. The WDF analysis, combined with a closely-related ambiguity-function analysis, provides the basic for non-stationary sampling conditions that can be used to determine the minimum number of samples required for the coherence function characterization.

We report here on efforts to characterise erbium-doped, heavy-metal fluoride glass microspherical lasers as a function of pump laser parameters, such as wavelength and power, and the temperature of the microsphere. The microspheres are fabricated from a novel material, ZBNA, optimised for its ability to act as a host for erbium and to favour laser emissions in the near infra-red region at 1.56 microns from the dopant. We work with microspheres that have typical diameters of ~80 microns. By attaching the microsphere to the tip of a narrow optical fibre a suitable method for manipulating the microsphere within the set-up has been developed. Pump light at 980 nm is coupled into the microsphere through evanescent wave tunnelling and propagates within the sphere in whispering gallery modes. A half-taper fibre is used as the coupling element. Strong green fluorescence at 540 nm has been observed. This indicates that the pump light is efficiently coupled into the sphere and that the alignment of the system is reasonable. We present an introduction to the fabrication of microsphere lasers, half-taper fibres and the physics of whispering gallery modes. In addition, we discuss the suitability of erbium as a lasing material when used in conjunction with the 980 nm pump light. Finally, we discuss our first experimental observations.

Digital holography is an inherently three-dimensional (3D) technique for the capture of real-world objects. Many existing 3D imaging and processing techniques are based on the explicit combination of several 2D perspectives (or light stripes, etc.) through digital image processing. The advantage of recording a hologram is that multiple 2D perspectives can be optically combined in parallel, and in a constant number of steps independent of the hologram size. Although holography and its capabilities have been known for many decades, it is only very recently that digital holography has been practically investigated due to the recent development of megapixel digital sensors with sufficient spatial resolution and dynamic range. The applications of digital holography could include 3D television, virtual reality, and medical imaging. If these applications are realised, compression standards will have to be defined. We outline the techniques that have been proposed to date for the compression of digital hologram data and show that they are comparable to the performance of what in communication theory is known as optimal signal quantisation. We adapt the optimal signal quantisation technique to complex-valued 2D signals. The technique relies on knowledge of the histograms of real and imaginary values in the digital holograms. Our digital holograms of 3D objects are captured using phase-shift interferometry.

Distortion-invariant identification (ID) tags are designed for remote identification and verification of objects. An optical code contained in an ID tag, placed in a visible part of an object, can be detected and verified by a remote receiver even if it captures a distorted version of the code due to in-plane rotations and variations in scale. In a general pattern recognition task, these distortions usually require to increase the level of complexity of the recognition system. We aim to use a less complex identification system that operates in real-time. Distortion-invariance is achieved by both multiplexing the information included in the ID tag and taking advantage of the topology of the tag. For security purposes, double-phase encryption has already been shown as an appropriate technique to encode the information. By using double phase encryption, a signature is hidden in an encoded ID tag. Once the ID tag is captured by the receiver and is decrypted, a correlation-based processor verifies the decoded information with a previously stored reference signal. The proposed system may have broad applications in transportation, in tasks such as the security control of authorized vehicles inside a restricted area, or in the control of objects for inventory purposes.

Model of Photonic crystals are easily available but the technology enabling to fabricate them with a good quality and at a reasonable price is not yet there. We chose colloidal assembling among the techniques permitting to fabricate photonic crystals. It seems to us that it is the most promising technique. We will discuss how to fabricate good photonic crystals without defects, with high refractive index contrast. We present two innovative fabrication techniques that increase the refractive index contrast of opal-based photonic crystals. To improve the structural regularity of the photonic crystals, the polycristallinity and the stacking defects of the opals were eliminated by modifying the surface potential of the substrates.

The inclusion of a nonlocal spatial response function in the Nonlocal Polymer Driven Diffusion model (NPDD) has been shown to predict high spatial frequency cut-off in photopolymers and more recently it has been shown that use of the nonlocal model is necessary to accurately predict higher order grating components. Here the nature of the temporal response of photopolymer is discussed and a nonlocal temporal response function proposed. The extended model is then solved using a finite element technique and the results discussed. Based on this model we examine the nature of grating evolution when illumination is stopped during the grating recording process. Refractive indices of the components of the photopolymer material used are determined and predictions of the temporal evolution of the refractive index modulation described. Material parameters are then extracted based on fits to experimental data for non-linear and both ideal and non-ideal kinetic models.

In recent years the development of new holographic memories based in photopolymers have a great goal. A new commercial holographic memories has been optimized by Aprilis and Inphase. The advantages of this type of materials to store information are well know: their high capacity and their fast random access. In the behaviour of this type of material two important factors determinate the quality of the material, the capacity and the energetic sensitivity. The base of the high capacity of the holographic memories is the high Bragg’s angular selectivity. The narrow curve of the angular scan are obtained when the effective optical thickness of material is high and permits record many holograms turning the plate only 3°. Others important factors are the dye and monomer concentration, high values of the concentrations origins high values of the index modulation (higher stored capacity, better energetic sensitivity and large dynamic range) but in when the dye and monomer concentrations are high all the light is absorbed in the first 200 μm of the material and the effective optical thickness of the grating recorded decrease (decrease the stored capacity) and the values of the noise are high in this case. In this work this attenuation of the index modulation in depth is having into account using rigorous couple wave theory to obtain the limit of the effective optical thickness for each composition of photopolymer. The optimal composition to obtain high stored capacity, high index modulation, good energetic sensitivity, high dynamic range and low noise are found.

The well known scaling law of holographic diffraction states that the replay diffraction efficiency η = Γ/M², where M is the number of gratings (pages) stored, and G is a constant system parameter. This is an important metric used to quantify HDS material performance, and a great deal of experimental work to validate this rule for a wide variety of materials, (photorefractives, polymers etc.) have been presented over the years in the literature. No paper detailing the theoretical basis of this law, (i.e. including specific material characteristics, the recording geometry and/or the electromagnetic replay conditions), for photopolymers has previously been presented. In a recent paper [1] we have described in a clear way the optimization of the recording schedule in a photopolymer material governed by the Nonlocal Polymerization Driven Diffusion model (NPDD). One of the main assumptions made in [1] is that a long material relaxation time can be permitted between exposures. Another was that no phase shifts of the exposing pattern took place between exposures. In this paper we discuss these assumption and develop an intermediate first-order model. In a second paper [2], based on the results presented in [1] we have shown that our optimized predictions are in agreement with the scaling law of holographic diffraction. Thus the law is shown to hold for photopolymer recording media governed by the predictions of the NPDD. Based on our analysis: (i) A media inverse scaling law is proposed; (ii) G is for the first time related to photopolymer material parameters and the hologram geometry and replay conditions; and (iii) The form and validity of the diffraction efficiency inverse square scaling law for higher diffraction efficiency gratings is commented upon. In this paper we also review this result.

In recent years the interest shown in dry photopolymer films as holographic recording materials have increased dramatically. The main reasons for this are the special properties of these media, such as high diffraction efficiency, low noise, real-time processing and low cost. Moreover, these materials are an important option for displays, high density data storage, micro-optical elements and other information processing applications. In these materials the hologram formation mechanism has been broadly studied, and it has been proposed that the temporal behavior of the diffracted beams depends mainly on the diffusion processes. Thus, the spatial modulation of the refractive index and its evolution over time is the result of non-uniform polymerization and the diffusion of monomers. In this work an analysis of the proposed models and the effect of the diffusion coefficient on the behavior of polyvinylalcohol-acrylamide-based compositions is realized.

Different electromagnetic theories have been applied in order to understand the interaction of the electromagnetic radiation with diffraction gratings. Kogelnik's Coupled Wave Theory, for instance, has been applied with success to describe the diffraction properties of sinusoidal volume gratings. Nonetheless the predictions of Kogelnik's theory deviate from the actual behaviour whenever the hologram is thin or the refractive index is high. In these cases, it is necessary to use a more general Coupled Wave Theory (CW) or the Rigorous Coupled Wave Theory (RCW). Both of these theories allow for more than two orders propagating inside the hologram. On the other hand, there are some methods that have been used long in different physical situations, but with relatively low application in the field of holography. This is the case of the finite difference in the temporal domain (FDTD) method to solve Maxwell equations. In this work we present an implementation of this method applied to volume holographic diffraction gratings.

In this work we analyse the very specific properties offered by volume holography when applied to image processing with no Fourier plane. Bragg diffraction, exhibited by holographic optical elements (HOEs), modifies the impulse response of an imaging system, facilitating spatial filtering operations with no need for a physical Fourier plane (Bragg processing). We show both experimental and simulated results with holographic phase gratings and with holographic lenses generated on a polyvinyl alcohol/acrylamide (PVA/AA) photopolymer. We determine which are the significant parameters to model the performance of the HOEs for Bragg filtering: orientation and bandwidth of the passband of the filter. We relate these spatial filtering parameters with their corresponding counterparts in volume holography. We also show how the local variation of these parameters is responsible for space-variance properties of the HOE when applied in Bragg processing. We have also analysed the impulse response characteristics of the Bragg filter together with the effects of the limited aperture of the imaging system.

A study of the light induced surface relief modulation in thin photopolymer layers is reported. Due to the nature of the photopolymer used no additional post-processing is required after holographic recording. An investigation of the dependence of the amplitude of the photoinduced relief modulation on different parameters of recording such as spatial frequency, intensity of the beams and times of exposure has been carried out. The surface relief modulation is characterized by white light interferometry. Photopolymer layer thickness ranges from 1-5 μm. A model of the mechanism of surface relief formation is proposed on the basis of the measured dependencies. A variety of patterns are inscribed in order to demonstrate the potential of this photopolymer in the design of different diffractive optical elements.

We present the results obtained using two different types of the new panchromatic ultra-fine grain emulsion BBVPan, manufactured by Colourholographics Ltd. The first emulsion type was manufactured by mixing three monochromatic precipitates, so that each silver halide grain is sensitised with one dye only. The second emulsion was obtained by making one single precipitate containing all three dyes mixed together, so that each silver halide grain may be sensitised by the three dyes. Both emulsions have been compared in order to produce multiple band holographic reflection gratings, multiplexed on a single layer of material. Three different laser systems were used: He-Cd (442 nm), frequency-doubled Nd-YAG (532 nm) and He-Ne (632.8 nm). High diffraction efficiencies, of over 52\%, were obtained for each of the three bands, with little wavelength shifting. Tests with diffuse objects have been also carried out, studying colour balance for each of the emulsions.

Free-radical photocurable hybrid material was used for the creation of crack free holographic gratings, showing only a refractive index modulation. Organic-inorganic materials based on the sol-gel synthesis of alkoxysilanes have demonstrated their great potential for coating and optical applications. In a first step, hydrolysis and condensation reactions were led under mild conditions along the same way as in classical sol-gel glasses. Partial elaboration of the silicate backbone was thus achieved. Then, with the use of a photoinitiator, free-radical polymerization was proceeded by irradiating the material under UV or visible light. A spatially controlled photopatterning can be thus achieved to create optical elements having the hardness of a glass-like material. The presented results concern the formation of gratings created by transmission using interference pattern at 514 nm. Diffraction efficiencies up to 90 % were reached for 1000 lines/mm in transmission, corresponding to a refractive index modulation amplitude of 4.10^-3 (according to the Kogelnik's theory). To elaborate non linear quadratic optical devices, hybrid sol-gel matrixes were doped with push-pull chromophores. Such a photosensitive system enables simultaneous photopatterning of the layer and poling of the NLO molecules. Experiments were realized during the photopolymerization step, in order to study the freezing of the non-centrosymetric orientation of the dispersed NLO chromophores.

Novel types of thin-film microoptical components have been found very advantageous for beam shaping of high-power and ultrashort-pulse lasers. Measuring techniques, nonlinear optics, materials processing, and further advanced photonic applications, will benefit from specific advantages. Compared to conventional microoptics, low dispersion and absorption as well as added degrees of freedom in structure and functionality are accessible. Single or multilayer designs, spherical and non-spherical profiles, extremely small angles, and flexible substrates enable key components for the tailoring of lasers in spatial, temporal, and spectral domain at extreme parameters. By vacuum deposition and selective etching transfer, a cost-effective fabrication of single or array-shaped refractive, reflective, or hybrid components is possible. During the last decade significant progress in this field could be achieved. Including very recent applications for spatio-temporal shaping and characterization of complex and non-stationary laser fields, the state of the art is presented here. Particular emphasis is put on the generation of localized few-cycle wavepackets from Ti:sapphire laser beams by the aid of broadband microaxicons. Special microoptics are capable of transforming vacuum ultraviolet radiation. Wavefronts of strongly divergent sources can be analyzed by advanced Shack-Hartmann sensors based on microaxicon-arrays. Single-maximum nondiffractive beams are generated by different approaches for self-apodizing systems. Prospects for future developments, like robust multichannel information processing with arrays of self-reconstructing X-pulses, are discussed.

Using high-intensity (around 200 GW/cm²) femtosecond 264 nm laser light and phase mask technique, Bragg grating inscription in a range of different photosensitive and standard telecom fibres (both H2-free and H2-loaded) was studied. The dependencies of the induced refractive index modulation versus the incident fluence were compared with similar dependencies for gratings fabricated by other existing methods. It was shown that at high-intensity UV laser irradiation, two-quantum photoreactions occur in the irradiated fibre core, which results in a significant photosensitivity enhancement of the investigated fibres in comparison with conventional low-intensity 248 nm exposure (by 6-128 times, depending on fibre type and irradiation intensity).

The complex transverse waveguide geometries twinned with the transcendental rate equations governing Erbium-Doped Waveguide Amplifiers (EDWA) warrant the application of intricate Numerical Methods. To date all models approaching the problem have incorporated a finite element scheme for the modal analysis of the waveguide in conjunction with either a Beam Propagation Method (BPM) or an explicit Runge-Kutta procedure towards solving the channel propagation equations. In deploying these models, a certain ambiguity lies in their practical utilisation enforcing a trade-off between simulation time and demands on computer memory. The underlying theory of the finite element method (FEM) for optical waveguide simulations comprises of a multitude of approaches to solving the scalar Helmholtz equation. Past FEM techniques were based on a combination of matrix sparsity manipulations and iterative techniques but today, even modest computers can be utilised in more direct but denser methods for eigenvalue solutions. This paper aspires to demonstrate an efficient modal analysis technique founded on an appropriate mesh with due consideration for both computational complexity and available Random Access Memory requirements. It is then trivial to continue from this modal field definition to the solution of the aforementioned rate equations for channel gain, noise or nonlinear losses including upconversion and cross relaxation in the EDWA by implementing a suitable boundary value problem approach.

In general most commercially available tools for optical integrated circuit (OIC) analysis are based on the beam propagation method (BPM) and involve a proportionally increasing amount of computational effort with increasing circuit size. An alternate approach to simulate the operation of complex OICs is proposed in this paper where a complex OIC is first divided into behavioural sub-components. Then a transfer matrix method (TMM) representation of each sub-component is employed to examine the functionality of the optical circuit. TMM matrix entries of the sub-components are generated via quasi-analytical techniques such as coupled mode theory for coupling sections and conformal mappings for bent waveguide sections. The above method can often provide a more transparent view of the circuit behaviour. A simulation and comparison of the TMM approach against a BPM analysis is provided for some fundamental circuit elements

A study was conducted to determine the alcohol concentration, refractive index and surface tension of binary solutions from multianalyser tensiotrace data. Characteristic vector analysis of multivariate response data has been successfully applied to a variety of optical tensiotraces to explore the quantitative capabilities of the multianalyser tensiograph. Singular value decomposition was used to determine the key vector i.e. the characteristics of the required signal as it affects the data. This vector is then optimised using the known established data to estimate the value of the unknown parameters. By the use of characteristic vector analysis the paper explores the relationship that exists between the tensiotrace features and the physical properties of a liquid. This paper shows the possibility of future work for identifying wines. A second study has been conducted where five wine samples were run on the multianalyser and their tensiotraces acquired. This preliminary study demonstrates that wine archiving and fingerprinting is possible.

The paper describes an ongoing effort to enable autonomous mobile robots to play soccer in unstructured, everyday environments. Unlike conventional robot soccer competitions that are usually held on purpose-built robot soccer "fields", in our work we seek to develop the capability for robots to demonstrate aspects of soccer-playing in more diverse environments, such as schools, hospitals, or shopping malls, with static obstacles (furniture) and dynamic natural obstacles (people). This problem of "Soccer Anywhere" presents numerous research challenges including: (1) Simultaneous Localization and Mapping (SLAM) in dynamic, unstructured environments, (2) software control architectures for decentralized, distributed control of mobile agents, (3) integration of vision-based object tracking with dynamic control, and (4) social interaction with human participants. In addition to the intrinsic research merit of these topics, we believe that this capability would prove useful for outreach activities, in demonstrating robotics technology to primary and secondary school students, to motivate them to pursue careers in science and engineering.

Digital holograms of real-world three-dimensional objects have been captured using phase-shift digital holography. These holograms have complex-valued pixels and a white noise appearance. Uniform and nonuniform scalar quantisation compression have already been applied to the hologram data with some success. Although each complex-valued pixel can itself be treated as a vector of length two, we extend the analysis using a multidimensional vector quantisation technique based on k-means clustering. This involves an a-by-b blockwise decomposition of the data and mapping it to an ab-dimensional space. Degradation due to lossy compression is measured in the reconstruction domain.

Photopolymer materials are good materials for the recording of holographic optical elements (H.O.E's), as they are inexpensive and self-processing. Understanding the mechanisms present during the fabrication of gratings in these materials is crucial in enabling further developments. One such mechanism is the presence of an inhibition period at the start of grating growth during which the formation of polymer chains is suppressed. Some previous studies have indicated possible explanations for this effect and mathematical models have been proposed to approximate the observed behaviour. We have carried out a set of experiments with the specific aim of developing an improved understanding of this process. In this paper we discuss these experimental results and provide a theoretical model, which describes the inhibition process in our Acrylamide based photopolymer and predicts this behaviour under certain conditions.

Using high-intensity (up to 500 GW/cm²) 264 nm laser radiation, we fabricated long-period fibre gratings (LPFGs) in standard telecom and photosensitive fibres and compared the inscription efficiency with that for other existing methods of recording. We studied the temperature sensing properties of the fabricated gratings and demonstrated the effect of thermal recovery of a LPFG resonance peak.

In this paper, we experimentally studied both the bright-field and fluorescence images of microspheres by conventional and confocal scanning polarization microscopes. A qualitative analysis have been given to show a physical picture on the imaging of the microspheres. Emission spectra from melamine formaldehyde microspheres stained with Ethidium Bromide or covered by thin shell of CdTe nanocrystals have been experimentally studied. We adopted analytical expressions describing the resonance spacing in order to determine the size of the microspheres.

An acrylamide-based photopolymer formulated in the Centre for Industrial and Engineering Optics has been investigated with a view to further optimisation for holographic optical storage. Series of 15 to 30 gratings were angularly multiplexed in a volume of the photopolymer layers with different thickness at a spatial frequency of 1500 lines/mm. Since the photopolymer is a saturable material, an exposure scheduling method was used to exploit the entire dynamic range of the material and allow equal strength gratings to be recorded. From this investigation the photopolymer layer's M/# was determined with regard to the recording geometry used. The temporal stability of photopolymer layers was studied in terms of diffraction efficiency and change of the reconstructed angle due to material shrinkage. In addition, the potential of the photopolymer as a holographic data storage medium was demonstrated by recording bit data-pages.

In this study we focus on the properties of acrylamide photopolymer layers about 1 mm thick with hydrofilic binder of polyvinyl alcohol and yellowish eosin as dye. We consider peristrophic multiplexing. Note the differences in the reconstruction step between the next two peristrophic multiplexing schemes: rotation axis parallel and rotation axis perpendicular to the hologram media. In the first case (parallel) a very thick media allows for a high storage density and a highly selective individual hologram reconstruction thanks to the Bragg angular selectivity. In the second case (perpendicular), an additional optical system is necessary to separate the various simultaneous holograms reconstructed. We show experimental evidence for the two schemes. We analyze the behaviour of the material when multiplexing diffraction gratings using peristrophic multiplexing. In the reconstruction step we observe differences, between the various multiplexed holograms, in their angular response shape. We consider that this is due to polymer diffusion in exposed areas or to the dye concentration variation with registered holograms number, because xantene dyes are bleached at the initiation step of radical polymerization reaction. The photopolymer composition is an important factor to be taken into account when single or multiple holograms are registered. The differences in both cases are considered in this work.

In Optical Signal Processing (OSP) one of the most important operations is the Optical Fourier Transform (OFT). Many different optical arrangements exist which allow implementation of the OFT, however one of the more popular is the Scaled Optical Fourier Transform (SOFT) because, as the name implies, this arrangement allows control over the scale of the output Fourier distribution. Using cylindrical coordinates we examine some of the practical limits introduced by the use of an illuminating spherical lens of finite aperture in the implementation of the SOFT. By deriving simple rules of thumb, based on examining phase and intensity deviations from the ideal unapertured case, we define a volume inside the geometric shadow, which we refer to as a sub-geometric shadow. Inside this sub-geometric shadow we show that the worst case errors in the resulting SOFT, arising due to diffraction, can be quantified and avoided.

Using matrix based techniques it is shown how the Space-Bandwidth Product (SBP) of a signal, as indicated by the location of the signal energy in the Wigner Distribution Function (WDF), can be tracked through any quadratic phase optical system whose operation is described by the Linear Canonical Transform (LCT). We extend this to include offset optical elements and systems, which are described by a more general transform-the Special Affine Fourier Transform (SAFT) or Offset LCT. It is shown that by decomposing the overall system matrix associated with the SAFT, into a product of the matrices representing the individual optical components, the spatial extent, its location and the signals bandwidth can be determined at any point in the optical system. This approach has application in many areas of optical signal processing; for example, numerical simulation, optical and digital compression, speckle metrology, optical encryption, optical filtering and the recording of processed images. The method is shown to be a simple tool of fundamental importance in the context of the entropy of the propagated signal and by tracking the Space Bandwidth product we can determine the quantity of information according to the Nyquist sampling theorem. We also discuss future work in relation to superresolution.

Recent improvements in holographic materials have led to advances in a variety of applications, including data storage and interferometry. To further increase the possibility of commercial applications in these areas it is necessary to have available an inexpensive, self-processing, environmentally stable material that has a good spatial frequency response. One promising type of material is Acrylamide-based photopolymer recording materials. The material can be made self-processing and can be sensitised to different recording wavelengths using different photosensitive dyes. The self-processing capability of this material simplifies the recording and testing processes and enables holographic interferometry to be carried out without the need for complex realignment procedures. Although this material has a lot of advantages over others it has significant disadvantages such as its spatial frequency response range (500-2500 lines/mm). Therefore, it is of ever-increasing importance to resolve uncertainties regarding optical and material properties, i.e. the refractive index and the diffusion constants. Using experimental diffraction efficiency measurements, a value for the refractive index modulation can be obtained. Then carrying out analysis using the Polymerisation Driven Diffusion model (PDD) values for the diffusion coefficients of various materials in the grating layer can be found. Applying the Lorentz-Lorenz relation, refractive index variations within the material can be more fully understood. With the resulting improved understanding it will be possible to improve the characteristics of photopolymer materials by altering the chemical composition, for example by controlling the crosslinker concentration or through the careful use of inhibitor and/or retarders to control the polymer chain growth.

Coherent optical signal processors, due to their ability to process and relay information in two dimensions, have been receiving increasing attention in recent years. These systems involve a coherent field being propagated through some bulk optical system consisting of thin lenses and sections of free space (such paraxial systems being described mathematically using the Linear Canonical Transformation). A Spatial Light Modulator (SLM) may be used to modulate the input digital data onto a coherent wave-field as well as to modulate the amplitude and/or phase of the complex wave-field at any desired plane. The complex field (amplitude and phase) at any desired plane may be recorded quantitatively using a CCD camera, using digital holographic techniques allowing the further processing of data digitally. Such hybrid optoelectronic systems have applications for 2D and 3D data processing covering fields as diverse as data storage, data security and pattern recognition. But devices such as SLMs and CCD cameras can represent only discrete levels of data necessitating a quantisation of continuous valued analog information. In this paper, we take the example of an optical system used to encrypt 2D and 3D data and evaluate the effect of the finite discrete levels of an SLM on the encryption/decryption process.

The hard research about the models to predict and understand the behaviour of photopolymers have as a results many interesting works for 2-dimensional cases. These studies permits obtain the mains parameters that governs the process in photopolymers with maximum thickness about 200 μm. Historically this materials, dry layers of photopolymers, have been used in many attractive devices and now a new application of this type of material is being developed: the application of photopolymers as holographic memories. The main characteristics of these layers of photopolymers are their high thickness (higher than 600 μm). In order to optimize this layers the original photopolymer composition has been changed, then a new parameters estimation has be done. In this work this study is made using PVA/Acrylamide photopolymer with layers around 800 μm of thick. The values of monomer and polymer diffusion are obtained and the values of polymerization rate constant and residual monomer are calculated too using and first harmonic diffusion constant. The validity of this model to study the layers with high thickness is evaluated, because this type of materials only a few percent of the initial light arrive to the depth zones of photopolymer.

In this paper we have studied the recording of Fourier holograms in a PVA-AA photopolymer, analysing the influence of beam ratio in the quality of the reconstructed images. As a result, it has been observed that the variation of the beam ratio produces significant changes in the response of the material, showing that there is a range of optimal values that gives the best performance of the photopolymer for the recording of Fourier holograms. Effects on edge enhancement as consequence of spatial filtering on the reconstruction stage has been observed for low values of beam ratio. The best beam ratio obtained from this study has been used for holographic multiplexing of four Fourier holograms.

The propagation of self-frequency shift of femtosecond soliton pulses is inevitably faced by self-frequency shift, which arises from the Raman effect. The non-linear phenomenon of cross phase modulation (XPM), arising from the collisions between pulses of different frequency, has been proposed as a way to counterbalance the shift in frequency and the subsequent time displacement. However, the co-existence of different frequency channels gives rise to new phenomena, like cross frequency shift and energy exchange between the channels, again due to the Raman effect. The current work is an analytical approach to the phenomena that arise during the co-propagation of sub-picosecond soliton pulses of different frequency. The analysis is based on the direct perturbation method, used on two couple NLS equations and provides insight to the spectral and temporal evolution of the pulses, and to their amplitudes' evolution as well. We look into the effects of incomplete and complete pulse collisions, while the pulses used in the examination are not only of equal widths.

We present the results of applying data compression techniques to encrypted three-dimensional objects. The objects are captured using phase-shift digital holography and encrypted using a random phase mask in the Fresnel domain. Lossy quantisation is combined with lossless coding techniques to quantify compression rates. Lossless compression alone applied to the encrypted holographic data achieves compression rates lower than 1.05. When combined with quantisation and an integer encoding scheme, this rises to between 12 and 65 (depending on the hologram chosen and the method of measuring compression rate) with good decryption and reconstruction quality. Our techniques are suitable for a range of secure three-dimensional object storage and transmission applications.

Noticeable refractive index modulations (difference between the refractive index of high-density areas and the index of low-density areas ~8x10^-3) can be created by photostructuration of acrylic films. The light pattern created by the interference of two plane waves induces inhomogeneous polymerization and mass diffusion processes, due to concentration gradients of monomer and dye, giving rise "in situ" to a structuration of the material at the microscopic scale. As the species involved in the initiation mechanism are gradually consumed as the hologram builds up, the incident dose is determined in order to reach full completion of the reaction at the end of the recording, i.e. to obtain stable gratings. This property makes photopolymers attractive materials for number of applications, especially in holography. A great advantage of these materials over other recording systems is that no chemical or heating post-treatment is required after illumination to reveal the hologram. Diffraction efficiencies of ca 80 % were obtained at 514 nm for transmission holograms with a fringe spacings between 0.2 and 5 μm. 675 mJ/cm² corresponding to a bleaching of the dye of 85% allows non-destructive reading at an active wavelength (green light). Miscellaneous photonic parameters (chemical composition, intensity, dose...) were tested by grating recording. Taking into account all these data, improvement of the material is possible in view of data storage applications.

Ocular complications in contact lens wearers are usually graded by specialists using visual inspection and comparing with a standard reference. The standard grading scales consist of either a set of illustrations or photographs ordered from a normal situation to a severe complication. Usually, visual inspection based on comparison with standards yields results that may differ from one specialist to another due to contour conditions or personal appreciation, causing a lack of objectiveness in the assessment of an ocular disorder. We aim to develop a method for an objective assessment of two contact lens wear complications: conjunctiva hyperemia and papillary conjunctivitis. In this work, we start by applying different image processing techniques to two standard grading scales (Efron and Cornea and Contact Lens Research Unit-CCLRU grading scales). Given a set of standard illustrations or pictures, image pre-processing is needed to compare equivalent areas. Histogram analysis allows segmenting vessel and background pixel populations, which are used to determine features, such as total area of vessels and vessel length, in the measurement of contact lens effects. In some cases, the colour content of standard series can be crucial to obtain a correct assessment. Thus, colour image analysis techniques are used to extract the most relevant features. The procedure to obtain an automatic grading method by digital image analysis of standard grading scales is described.

Laser drilling has become a common processing step in the fabrication of printed circuit boards (PCB's). For this work, a recently developed enhanced peak power CO₂ laser (~2.5 kW peak power, 200W average) or ultra-super pulse (USP) laser is used to drill alumina and copper coated dielectric laminate materials. The higher peak power and faster response times (than conventional CO2 lasers) produced by the USP laser are used to produce high speed alumina laser scribing and copper coated laminate microvia drilling processes. Alumina is a common PCB material used for applications, where its resistance to mechanical and thermal stresses is required. Here we present a comprehensive study of the melt eject mechanisms and recast formation to optimise the speed and quality of alumina laser scribing. Scribe speeds of up to 320 mms^-1 (1.8 times current scribe rate) have been achieved using novel temporal pulse shapes unique to the USP laser. Also presented is the microvia drilling process of copper dielectric laminates, where the multi-level configuration presents different optical and thermal properties complicating their simultaneous laser ablation. In our experiments the USP laser has been used to drill standard thickness copper films (up to 50 μm thick) in a single shot. This investigation concentrates on understanding the mechanisms that determine the dielectric undercut dimensions.

Many of the next generation of high-tech consumer products will take advantage of the manufacturing advances in micro-optics that we are currently taking place. One of the most important areas of micro-optic research is that of microlens design and fabrication. The importance of this area is perhaps highlighted by the range of competing fabrication technologies. Each having important advantages/disadvantages for a given application. It is therefore important to pursue other possible fabrication methods. In this paper we examine two of these novel fabrication techniques: (1) Photo-embossing in holographic recording materials, and (2) Microfluidic lens fabrication. The first of these techniques offers the possibility of combining the advantages of diffractive optical elements with those of conventional refractive optical elements. The second technique in combination with inkjet deposition technology can be used to produce a wide range of optical elements (lenses) and offers the possibility of controlling the lens profile in real time during formation using electric fields.

A time-resolving Langmuir probe has been used to study the plasma plumes produced by ablation of silver with 200 femtosecond laser pulses at fluences of 1-12 J cm^-2 at a central wavelength of 775 nm. Initial results have shown that surface contamination, and subsequent recontamination, can significantly influence the time of flight (TOF) signals obtained using the Langmuir probes. Surface conditioning techniques have been developed to overcome these influences. The TOF signals have been used to establish that the threshold fluence for the laser produced plasma in silver, under the present operating conditions, occurs at 1.04 J cm^-2. The angular dependence of the magnitude of the ion yields and energies, at the time when the ion flux is maximized, agree with the predictions of Anisimov’s self-similar isentropic model of the plasma expansion.

The steadily rising world market volume in the micro system technology area has made higher and higher claims on the micro production technologies so that there is still a shortage in the production of metallic components with total dimensions of only few millimeters and the smallest structures are in the few micrometer range. Currently, the methods of the rapid prototyping area are approved and in relation to the product development one of the most essential instrument of the component manufacturing, in which particularly the macroscopic 3D laser beam processing has proved its high potential with regard to flexible manufacturing of metallic components. New developments in the beam sources area open possibilities of using this method also for the production of micro components. Hence, the subject of the present work is the development of a suitable system concept for 3D micro cladding and/or sintering. This concept has been qualified by theoretical considerations as well as experimental investigations. The developed, fully automatically manageable facility contains a Yb:YAG disc laser of a laser beam focus diameter to be set below 10 μm. As for quality assurance, a pyrometric temperature regulation has been integrated into the facility, which controls the temperatures in the welding bath with the help of a focusable measuring spot down to 50 μm. The process takes place in a likewise controlled protection gas chamber in which atmospheres with an oxygen content below 100 ppm can be guaranteed. The aerodynamic micro particle delivery will be possible with the help of developed combination procedures. The focusing in the melting pool occurs through a coaxial nozzle. Experimental investigations confirm the high potential of this method through which sintered layers smaller than 15 μm can be generated. Samples will be shown.

Percussion drilling of blind holes and vias in Kapton film was investigated using Q-switched solid state lasers operating at UV (355nm) and VUV (266nm) wavelengths. Holes were analyzed using different methods such as scanning electron microscopy (SEM) and surface profilometry. Ablation rates for the two wavelengths are compared. No abrupt thresholds were found and there was no evidence of an incubation effect within the first few pulses. Introducing pauses during the drilling increased the number of shots required for perforation of the film. The effects of fluence on diameter, depth and taper of the holes are presented. Smaller and neater holes are achieved more accurately with a lower fluence. An observed skin effect brought about by long exposure to low fluence VUV laser light is also discussed.

The increasing complexity of microelectronics/ engineering devices and the requirement for higher yields and automated production systems place stringent demands on the assembly techniques and performance requirements of materials, machining and joining techniques. This has led to increasing interest in the use of low power lasers for machining, welding, soldering and marking of small assemblies. Of particular interest to micro-component industries is the ability of such lasers to apply controlled amounts of energy in precise areas, utilizing extremely low heat input, resulting in very low distortion, and coupled with the ability to operate at high production rates in a flexible manner. The majority of these applications comprise thin materials, less than 1mm thickness. This paper describes some of the cutting, joining, drilling and marking results achieved with a high beam quality low power pulsed Nd: YAG laser.

Integrated optical circuits are an important technology for future high tech products. At present there is great interest in producing polymer based optical circuits. These circuits have a number of potential advantages over current silica/semiconductor based systems. These polymer optical circuits have been used to produce waveguide technology. However in general the production of laser systems for these circuits still depends on older semiconductor technologies. Polymer lasers provide a possible candidate for integrated flexible lasers. Many of the systems demonstrated to date use silica/semiconductor substrates to provide sufficient refractive index variation to provide efficient feedback. A novel alternative to this technology is the holographic distributed feedback (DFB) laser geometry. In this system the lasing material is dispersed in a photopolymer holographic recording material. DFB is then provided by a refractive index structure recorded in the material using holographic techniques. In this paper we discuss a range of holographically recorded feedback geometries and examine the possibility of using this technique to produce organic DFB lasers using non contact holographic patterning.

Bone-bonding implants include some of the commonest biomaterials currently used. The useful lifetimes of these materials are limited in part by the capacity of the material to support an intimate bond with the tissue in which they are implanted. A number of materials currently used have either good mechanical properties but poor biological responses, or have the ability to form suitable bonds with bone but lack the requisite strength, wear resistance, etc. In particular, polymeric materials have generally been shown to be inert with respect to bone. We report on our work on developing methods to surface treat polymers to encourage colonisation by bone, either for clinical implantation or in vitro tissue engineering applications. Polymers were treated by one of two methods; either 1) using an excimer laser to machine arrays of grooves in the surface; the periodicity of the grooves was varied from a few hundred nanometers to 10 μm; or 2) using an excimer lamp to affect the chemistry of the surface layer by breaking surface bonds and incorporating atmospheric oxygen. Surface structures of samples treated by method 1 were examined using Scanning Electron Microscopy (SEM), White Light Intereferometry and Atomic Force Microscopy (AFM) and surfaces of samples treated by method 2 were examined by using contact angle measurements which indicated a higher surface energy. The difference in cellular response to the control surfaces and modified surfaces was investigated. In conclusion, these methods provide viable means for altering polymers and may generate improved polymers for bone-bonding applications.

Fused biconic tapered (FBT) couplers are essential components in today's telecommunications networks where they are used for a number of different applications. The manufacturing process consists of aligning two adjacent fibres from which the buffer has been stripped, and subsequently heating and stretching them, creating an input taper, output taper either side of the fused coupling region. It is the coupling region where energy transfer between cores is possible; this gives the device its main characteristics, and the basic geometry can be used to create a range of devices such as 3 dB splitters, tap couplers, WDMs, etc. Low losses for these devices are achievable if made with reference to the adiabatic approximation. In this paper we report the development of a laser-based rig for the manufacture of couplers in which a CO₂ laser replaces the gas torch typically used as a heat source in modern manufacturing processes. In addition to the use of a laser source, we describe the integration of advanced optical techniques and feedback mechanisms to improve the workstation's reliability and flexibility. These characteristics should be advantageous for efficient manufacture of standard devices and novel devices for niche applications.

Excimer based laser ablation of micro-fluidic circuits for micro-total analysis systems (μTAS) is an alternative to more expensive techniques of LIGA or micro-moulding. In the interests of developing a rapid prototyping method for direct writing of micro-fluidic circuits in polymer materials the ablation process was characterised using Design of Experiment techniques and a robust full factorial model was developed. Input factors of pulse energy, repetition rate, scan speed and number of passes were considered. Output responses of trench bottom width, sidewall angle, trench depth and trench roughness were measured. From this a prediction equation was created to forecast the output responses prior to machining and to allow the development of a process prior to machining. The accuracy of the prediction equation is discussed for four materials; Polystyrene, Polycarbonate, Non-CQ grade PMMA and CQ grade PMMA. For the four materials studied the response of Polystyrene and Polycarbonate were similar while the two grades of PMMA behave differently.

Polymers play an important role in many applications such as microelectronics and medical devices. Micro-channels and shaped holes can be produced by 2.5D micro-structuring with excimer laser sources using mask projection. The industrial cost associated with these processes can be greatly reduced by the use of solid-state lasers due to their lower cost and maintenance. For this purpose, we investigate the interaction of polyimide (Kapton) with solid-state lasers emitting in the UV (266 & 355 nm) spectral range. The study presents a comparison of the ablation profiles obtained for different laser sources and these are discussed in term of roughness and efficiency. Limitations on the actual motion system (scan-head) are evident and the need to control the material removed by a small Gaussian beam in terms of overlapping for the direct writing process will be highlighted.

Hands-On Optics: Making an Impact with Light (HOO) is a three-year informal science program designed to bring optics education to tens of thousands of underserved students nationwide. SPIE-The International Society for Optical Engineering and the Optical Society of America (OSA), along with Mathematics, Engineering, Science Achievement (MESA) and the National Optical Astronomy Observatory (NOAO), were awarded a $1.7 million grant from the U.S. National Science Foundation (NSF) in 2003 to implement this national science enrichment program intended for children in middle school (approximately 11 to 14 years old).

This paper discusses the optics content of the UK A level Advancing Physics course. Some of the novel teaching approaches are presented as well as a teaching sequence. Computer animations and lab work will be demonstrated in the main talk.

Laser Photonics has been highlighted by many as THE Technology of the 21st Century. However, there are few obvious opportunities for students to see a Laser in operation in circumstances beyond some simple low power Laser Interferometry demonstrations, or the use of Laser Pointer Pens. As part of an educational initiative, PION LASER SENSORS within the University of Salford has developed a series of laboratory design and construction Projects that involve both the opportunities for, and the innovative creation of, visually attractive operative applications of low power Laser Photonics. These highly functional Laser Photonics Projects range from the transmission of audio signals to a written alphabetical letter recognition and Braille converter sensor for a visually impaired person; from a Laser speckle eye-sight testing system to a prototype mobile robotic guide for a blind person.; from a novel type of Laser seismograph to an equally novel set of Laser measurement callipers; from a Laser activated pair of walking feet to an optical feedback system to maintain a horizontal surface within a vehicle traversing rough terrain. This type of low power Laser Photonics design and construction Project not only provides the opportunity for students to become involved with some highly creative and innovative laboratory opportunities, but the experience clearly enthuses the students towards many aspects of Physics, Medicine, and Engineering through a sense of personal achievement resulting from a realization of their imaginative thinking sills, combined with their acquired manual skills.

The manufacturing firm established by Thomas Grubb and continued by his son Howard was a unique high-technology enterprise in nineteenth-century Ireland. For the best part of a century the Grubbs constructed many of the world's largest and best telescopes as well as producing a wide range of precision optical and mechanical instruments. In 1925 the daughter firm of Grubb-Parsons was founded in Newcastle-upon-Tyne and it continued the tradition of constructing large telescopes for another sixty years.

This study outlines ongoing research within the area of physics education, namely the investigation of the relationship between conceptual understanding and quantitative problem-solving. Industry, society and research need graduates to be excellent problem solvers with an ability to conceptualise and transfer their understanding and knowledge. However recent research has shown that physics students are not developing the conceptual understanding necessary to become adept problem-solvers. Physics education tends to rely on the assumption that students will develop an understanding of the conceptual nature of physics by solving quantitative problems. Research has shown that this is not the case and students cannot develop as problem-solvers without first having the conceptual understanding. Many of these physics graduates go on to work in optics, in areas such as nanotechnology, photonics fabrication and optical sensing. This research involves an investigation of student learning in physics and the impact this has on conceptual understanding and their ability to solve quantitative and qualitative problems. It builds on research carried out in the United States in order to obtain a better understanding of how students learn physics and the difficulties they have developing an understanding of the conceptual nature of physics. It aims to develop a systematic way of identifying students’ misconceptions in physics and to assess the affect these have on student learning and the development of understanding. This research will inform teaching and assessment practices, not only in physics education but also in other disciplines so that third level education can produce better problem-solvers for industry, research and a knowledge-based society.

We describe a course on the propagation of electromagnetic waves that is built around a problem-based learning (PBL) problem. The paper will describe how the problem was integrated into a pre-existing course that was perceived as highly successful (and hence not apparently in need of enhancement) by linking theory with experiment. The problem involves possible methods of searching remotely for leaks in water pipelines crossing a desert region by comparing the dielectric constant of wet and dry sand at various frequencies. The potentially wide-ranging learning objectives are restricted to the various properties of the reflection of plane waves at interfaces. Even so, any one PBL group can carry out only a small subset of the possible experiments in the allotted time. Thus, an interesting feature of the problem is that the reason that the experiments do not appear to give results with textbook accuracy can only be discovered by cooperation amongst the groups. This gives an added focus to the group presentations.

We describe a Collaborative Writing Environment for use in School projects. We describe the Environment, the factors that influenced our design, a system walk-through and its relevance to the Revised Irish Primary Curriculum. Although this Environment has been developed for Astronomy based projects, our development approach has been to develop an environment that is generic and customisable, and as such is applicable to writing projects in all subject areas.

The rapidly emerging field of MEMS (micro electromechanical systems) has recently seen a proliferation of microscale devices and processes. Indeed, microsystems and nanotechnology has from its origins in the integrated circuits industry now become an extensive field of research encompassing everything from biosensors with near real-time diagnostics to power MEMS for portable devices, enabling vastly improved performance to power consumption over their macro counterparts. The paper uses relevant contemporary issues that arise from conceptual limitations in this burgeoning field to illustrate and highlight some critical analysis of the key educational issues involved in teaching in this vital area. The paper considers a number of political-strategic issues arising for Ireland directly out of the nano-biotechnology revolution. It also highlights a number of relevant concerns that can be addressed by educational initiatives. Theoretical and philosophical concepts regarding changes in thinking surrounding recent developments are also explored, with some specific primary science discussion made on research issues and second-third level education. The paper ends with an attempt to identify the major opportunities for Ireland and highlights the changes that science and technology will wrote for an Ireland ready or not, to face a new reality that is also no respecter of any country's past successes.

Optical fibre communications has proved to be one of the key application areas, which created, and ultimately propelled the global growth of the photonics industry over the last twenty years. Consequently the teaching of the principles of optical fibre communications has become integral to many university courses covering photonics technology. However to reinforce the fundamental principles and key technical issues students examine in their lecture courses and to develop their experimental skills, it is critical that the students also obtain hands-on practical experience of photonics components, instruments and systems in an associated teaching laboratory. In recognition of this need OptoSci, in collaboration with university academics, commercially developed a fibre optic communications based educational package (ED-COM). This educator kit enables students to; investigate the characteristics of the individual communications system components (sources, transmitters, fibre, receiver), examine and interpret the overall system performance limitations imposed by attenuation and dispersion, conduct system design and performance analysis. To further enhance the experimental programme examined in the fibre optic communications kit, an extension module to ED-COM has recently been introduced examining one of the most significant performance parameters of digital communications systems, the bit error rate (BER). This add-on module, BER(COM), enables students to generate, evaluate and investigate signal quality trends by examining eye patterns, and explore the bit-rate limitations imposed on communication systems by noise, attenuation and dispersion. This paper will examine the educational objectives, background theory, and typical results for these educator kits, with particular emphasis on BER(COM).

We discuss classical experiments in the field of laser speckle interferometry. The typical optical setup consists of a laser diode and off-the-shelf optical elements, like a lens to expand the beam and plane mirrors to deflect it. A low-cost commercial CCD photocamera is used to acquire the speckle images. Items investigated are diffusing objects, illuminated with the laser diode and imaged on the CCD under appropriate experimental conditions. Pictures are taken both with the object at rest and under stress. The pictures are subtracted from one another with a standard software, pixel by pixel; the subtraction reveals fringes of the deformation occurred between the two exposures. With interferograms obtained in this way, we can study mechanical systems with an accuracy of the order of the wavelength of the light source used. Changing the optical setup, the measurement becomes sensitive to stresses along the camera optical axis direction (out-of-plane) or in the perpendicular plane (in-plane). Making long-time exposures it is also possible to study vibrational modes of suitable items (time-average). Three different setups are investigated and examples of measurement are reported.

There seems to be no single simple representation or set of concepts available to provide an 'intuitive umbrella' under which, for example, classical speckles based metrology, quantum optics, and optical signal processing can be simultaneously seen by the student as part of the pleasing whole that is modern optics. In this paper we propose to show how the early introduction of the concepts of the Wigner (Ville) Distribution Function, can be achieved, without the early recourse to large amounts of mathematics. We show how a whole series of extremely high-level concepts and ideas then become accessible to the student. As examples of such ideas I mention the Linear Canonical Transformations, the Space Bandwidth Product and sampling issues in the numerical simulation of optical systems. We believe that the result, which we refer to as Wigner Optics, provides a consistent and intuitively pleasing structure, which not only unambiguously relates geometric and ray optics with Fourier and wave optics but also encourages the student to place these models in the context of signal processing. Familiarity and early exposure to the WDF has the further advantage that it prepares the student for material on more advanced concepts, i.e. partially coherent and quantum optics.

An outline of the thermal vision systems curriculum for 5th year undergraduate students at the Branch of Department of Electro-Optical Devices, the Moscow State University of Geodesy and Cartography (MIIGAiK) attached in Central R&D Institute "Cyclone" is presented. Contents and some methodological aspects of the course "Thermal Vision Systems" teaching are described.

The development of optical engineering, photonics, optical telecommunications and networking courses in the Carlow Institute of Technology are briefly outlined in its national and local historic context. The experience of running various pioneering technician and degree courses in Carlow using assessment procedures designed to test specified learning outcomes is described. A critical review of the use of these educational methods for optical engineering is then made based on the personal experience of one of the author's postgraduate experience in studying in both the Glasgow universities. A differential study is presented of the Scottish and Irish experience, made from the point of view of best practice in educational methodology, as it applies specifically to teaching the high level skills required for engineering design in optical engineering programmes. Details on technology teacher training are presented and some discussion is given on relevant educational initiatives for this area. Possibly the first ever quantitative taxonometric analysis of the 2003-4 examination papers from a leading Institute of Technology in Ireland is undertaken to provide an insight into the present practice of the lecturers and educational managers running this programme. This analysis reveals the coordinated teamwork involved in the course implementation and identifies that various roles that are taken by individual courses in the context of balancing appropriately the whole educational programme. Critical observations on some of the programmes for technician, technologist and degree programmes should enable the delivery to be improved. The statistical analysis of results should also deliver improvements in retention rates of the students. The paper ends with a observations on some useful lessons to be drawn from this wide-ranging review of world, Scottish and Irish experience.

The VTIE Telescope Resource Management System (TRMS) provides a frame work for managing a distributed group of internet telescopes as a single "Virtual Observatory". The TRMS provides hooks which allow for it to be connected to any Java Based web portal and for a Java based scheduler to be added to it. The TRMS represents each telescope and observatory in the system with a software agent and then allows the scheduler and web portal to communicate with these distributed resources in a simple transparent way, hence allowing the scheduler and portal designers to concentrate only on what they wish to do with these resources rather than how to communicate with them. This paper outlines the structure and implementation of this frame work.

In 1991 the TIE (Telescopes in Education) Foundation provided schoolchildren with the ability to access professional observatory telescopes remotely. TIE has raised the profile of astronomy and science among schoolchildren. Since the initiation of this facility the TIE Foundation have spread their reach from one telescope in the US to many telescopes and many schools across the globe. The VTIE (Virtual Telescopes in Education) project was launched in 2001 to build on the success of TIE. The VTIE VLE (Virtual Learning Environment) provides a Web portal through which pupils can create a scientific proposal, retrieve astronomical images, and produce a scientific paper summarizing their learning experiences of the VTIE scientific process. Since the completion of the first formative evaluations of VTIE (which involved over 250 schoolchildren) it has been observed that the participating schoolchildren have had difficulty completing and understanding the practical imaging aspects of astronomical science. Our experimental observations have revealed that the imaging tools currently available to astronomers have not ported well to schools. The VTIE imaging tools developed during our research will provide schoolchildren with the ability to store, acquire, manipulate and analyze images within the VTIE VLE. It is hypothesized herein that the provision of exclusively child-centered imaging software components will improve greatly the children's empowerment within the VTIE scientific process. Consequentially the addition of fully integrated child-centered imaging tools will contribute positively to the overall VTIE goal to promote science among schoolchildren.

Darwin's seminal work 'Origin of Species' immediately attracted the 19th Century scholar John Tyndall. Darwin's book was, and is, a hypothetical and metaphysical treatise but it has great explanatory power. The cryptically named 'X Club'-9 members, including Tyndall-was formed to defend Darwin's outrageous ideas. Tyndall's responsibilities within this X-Club were to support Darwin's theory through experimental studies in solar physics and chemistry. Research was, of course, directed at understanding the physical basis of life on earth. The studies founded modern meteorological sciences, nephelometry and bacteriology (pace, Pasteur). This current essay details some of the historical background of Tyndall's work in natural philosophy; allowing the value of Tyndall's work to be assessed more objectively. Also it evaluates their respective contributions to the founding of this different way of looking at the world. The work of Tyndall at the 1868 Norwich 'British Association for the Advancement of Science' (BAAS) Meeting and the later internationally explosive 1874 Belfast BAAS meeting are examined in the light of his research. Some amplification of Tyndall's works both philosophically and historically is attempted.

Albuquerque Technical Vocational Institute (TVI) is collaborating with the National Science Foundation (NSF) funded Center for Biophotonics Science and Technology (CBST) headquartered at the University of California, Davis in order to develop a biophotonics curriculum for community colleges nationwide. TVI began the formal collaboration to bring about critically needed training and education that will ultimately create new jobs and employment opportunities in the field of biophotonics. "Biophotonics" is the science of generating and harnessing light to detect, image and manipulate biological materials. CBST chose TVI as a partner because of the Institute's current high-level photonics and biotechnology programs. In addition, TVI is a part of the "Albuquerque Model" that involves exposure to photonics education from the middle school level through graduate education at the University of New Mexico. Three middle schools feed into the West Mesa High School Photonics Academy, whose students then move on to TVI for advanced training. CBST brings together scientists, industry, educators and the community to research and develop applications for biophotonics. Roughly 100 researchers-including physical scientists, life scientists, physicians and engineers from UC Davis, Lawrence Livermore National Laboratory, UC Berkeley, UC San Francisco, Alabama A&M University, Stanford University, University of Texas at San Antonio, Fisk University and Mills College-are collaborating in this rapidly developing area of research. Applications of biophotonics range from using light to image or selectively treat tumors, to sequencing DNA and identifying single biomolecules within cells.

A novel method for the measurement of ultra-high absorbance liquids has been devised and details are given of a new ultra absorbance instrument developed specifically for these thin liquid film measurements. The instrument specifically constructed for monitoring and measuring sunscreen products has been tested using locally produced sunscreen products. This new approach has been made possible by the development of very accurate liquid micro-dispensers and details are given of the novel procedure to carry out these measurements. Detailed description of the apparatus construction is given with photographs of the apparatus. The work described is largely based on research and quality control measurements of Parasol suncare products. Results on the reproducibility of measurements taken with the UAI for a commercial range of factor 20 sunscreen liquid are given and these have been used to validate the performance of the instrument. It is believed that the absorbance measurements described here are perhaps the largest ever reported. In addition, the photostability of this product has been monitored in aging tests. Finally, some studies have been done on two other commercially available factor 20 products that show that these are significantly worse with regards to both protection from ageing and burn.