Table of contents

When the constitutive materials of photonic crystals (PCs) are magnetic, or even only a defect introduced in PCs is magnetic, the resultant PCs exhibit very unique optical and magneto-optical properties. The strong photon confinement in the vicinity of magnetic defects results in large enhancement in linear and nonlinear magneto-optical responses of the media. Novel functions, such as band Faraday effect, magnetic super-prism effect and non-reciprocal or magnetically controllable photonic band structure, are predicted to occur theoretically. All the unique features of the media arise from the existence of magnetization in media, and hence they are called magnetophotonic crystals providing the spin-dependent nature in PCs.

Fe/c-Si devices have been irradiated with 100 MeV swift heavy ions of Fe⁷⁺ at a dose of 10¹⁴ ions cm⁻². The devices have been studied using XRD and SEM. Electronic transport across the interface of the devices (i.e. in current perpendicular to the plane (CPP) of the device) has been measured from room temperature to liquid N₂ temperature. The CPP current has also been studied in a magnetic field (up to 10 kG which has been applied along the plane of the device). Unirradiated devices do not show any effect of the magnetic field whereas large magnetoresistance (MR) up to 2400% giant magnetoresistance (GMR) has been observed for the irradiated devices. An M–H study of the irradiated devices shows a behaviour of coupled magnetic nanograins. The results have been understood by considering the formation of a nanogranular magnetic silicide phase (of Fe₅Si₃) due to intermixing at the interface (as evidenced from XRD and SEM features). The electronic and magnetotransport characteristics of the irradiated devices show that the interface becomes intimate enough (due to the irradiation induced strong intermixing) to result in a tunnel transmission of carriers. A tunnelling barrier seems to form (for the irradiated ones) between Fe₅Si₃ magnetic nanocrystals separated by a nanometre scaled silicon tunnelling barrier. The observed very large (strong) GMR could be due to the spin dependent interface scattering in the presence of the strong AF coupling across the tunnelling barrier.

Cubic silicon carbide (3C-SiC) powder was synthesized at 460 °C in the ScCO₂-metallic Na system, using cheap industrial FeSi_δ alloy (⩽500 mesh) and CO₂, as silicon and carbon sources, respectively. The products were characterized by x-ray diffraction and Raman spectrum analysis. The results show that increasing the heating-up rate, adding a metallic sodium dose and prolonging the heating time favour the formation of 3C-SiC. A very strong photoluminescence band peaking at 436 nm was observed, showing a blue shift compared with the blue–green luminescence from films of 3C-SiC. A possible mechanism behind the blue shift is discussed.

We report the synthesis of solvent-stabilized lead-iodide nanoparticles, using a convenient route involving coordinating solvents. The resultant colloids show strong absorption features in the ultraviolet region of the optical spectrum, which are consistent with the formation of semiconducting nanocrystals of lead (II) iodide. An effective-mass approximation model of quantum-confined states is in good agreement with the observed transition energies, giving strong indications of the particle morphologies and dimensions. Intense photoluminescence is also observed, with some spectral tuning possible with ripening time, giving a range of emission photon energies approximately spanning from 2.5 to 3.0 eV. We measure photo-stable luminescence quantum efficiencies of around 20% in solution, increasing to up to 30% if the coordinating ligand is exchanged for a Lewis-base capping layer. This demonstrates the potential for the utilization of lead-iodide nanocrystals in visible optoelectronics applications.

A low-temperature method for growing (0001)-oriented one-dimensional ZnO nanopillars using electrodeposition in a simple zinc nitrate aqueous solution without any template is presented. The 20–100 nm diameter ZnO nanopillars emitted ultraviolet light at around 3.30 eV due to the recombination of the bound excitons and visible light at 2.30–2.55 eV at room temperature. Since the diameter and length can be controlled easily, some applications for use in ultraviolet light lasing diode and organic solar cells will be made.

Dosimeters of MgB₄O₇ doped with Dy and Na have many valuable features such as high sensitivity, tissue equivalence, low fading, non-requirement of annealing and insensitivity to light. Thermoluminescence studies of Dy and Na doped MgB₄O₇ samples showed that a glow emission peaked at about 195 °C. In this study, the trapping parameters associated with the main dosimetric peak, namely at 195 °C, of Dy and Na doped MgB₄O₇ are investigated. Isothermal luminescence decay, glow curve shape, initial rise (linear regression) and T_m − T_stop methods were used. We report the results on the kinetic behaviour and activation energy determination of the peak occurring at 195 °C with a moderate heating rate of 2 °C s⁻¹. The average activation energies obtained by the isothermal luminescence decay method, glow curve shape method and initial rise method are calculated to be 1.03 eV, 0.95 eV and 0.89 eV, respectively. The methods mentioned above indicate that the dosimetric peak may consist of one or more second-order components. The frequency factors obtained by the three methods are 3.5 × 10¹⁰ s⁻¹, 1.6 × 10⁹ s⁻¹ and 3.4 × 10⁸ s⁻¹, respectively. Results obtained using all these methods are compared and discussed.

We present a study of the joint influence of temperature and fabrication defects on the operation of quantum-dot cellular automata (QCA) devices. Canonical ensemble, a Hubbard-type Hamiltonian and the inter-cellular Hartree approximation were used, and a statistical model has been introduced to simulate defects in the QCA devices. Parameters such as success rate and breakdown displacement factor (BDF) were defined and calculated numerically. Results show the thermal dependence of BDF values of the QCA devices. The BDF values decrease with temperature. The joint influence of randomly missing dots and temperature was also studied.

A new tolane-base liquid crystal, 4'-heptyl-3-fluoro-4-isothiocyanatotolane (7TOLF), and a biphenyl-base nematogen, 4'-heptyl-3-fluoro-4-isothiocyanatobiphenyl (7BF), have been investigated for the first time to determine their electro-optical behaviour and third order non-linearity using the static Kerr effect method. Both the nematic compounds have a fluorine atom attached to the phenyl-NCS moiety. They possess the same polar head group (-NCS) and alkyl tail (-C₇H₁₅). So the effect of the tolane group of nematogen on the electro-optical behaviour was investigated and compared. The temperature dependence of the electric Kerr constant in the isotropic phase and the pre-transitional behaviour has been investigated for these high birefringence compounds in the isotropic phase. Both the compounds have a positive and large Kerr constant which increases with decrease in temperature. The Landau–de Gennes model was obeyed for these compounds. For 7TOLF, the observed value of susceptibility, χ³ is about 228 times higher than that of CS₂. The experimental Kerr effect data were also compared with those of the well-studied nematic liquid crystals.

Constant temperature hot gas readers are widely employed in thermoluminescence dosimetry. In such readers the sample is heated according to an exponential heating function. The single glow-peak shape derived under this heating condition is not described by the TL kinetics equation corresponding to a linear heating rate. In the present work TL kinetics expressions, for first and general order kinetics, describing single glow-peak shapes under an exponential heating function are derived. All expressions were modified from their original form of I(n₀, E, s, b, T) into I(I_m, E, T_m, b, T) in order to become more efficient for glow-curve deconvolution analysis. The efficiency of all algorithms was extensively tested using synthetic glow-peaks.

Thermoluminescence (TL) glow-curves measured using an exponential heating function (EHF) in constant temperature hot gas readers, cannot be analysed using the existing single TL glow-peak equations derived assuming a linear heating rate. In the present work single TL glow-peak equations, which were recently derived assuming an EHF, are used to perform a computerized glow-curve deconvolution analysis of experimental glow-curves measured using a stable temperature hot gas reader. Glow-curves of the most commonly used dosimetric material LiF:Mg, Ti were analysed using the first order kinetics glow-peak equations. The glow-curves were analysed for samples that were pre-irradiation annealed at 400 °C for 1 h and 100 °C for 2 h, with and without a post-irradiation annealing at 80 °C for 1 h. TL glow-peak equations of the general order kinetics were used to analyse experimental glow-curves of the dosimetric material Li₂B₄O₇ : Mn, Si. The results showed that the recently derived TL equations are very efficient for analysing glow-curves measured using stable temperature hot gas readers.

Single crystals of CuGa₃Se₅ have been grown by chemical vapour transport. Optical properties of CuGa₃Se₅ have been investigated in the temperature range between 10 K and room temperature 300 K. The temperature dependence of the energy gap was studied using the Einstein and Pässler models. The values of the band gap at T = 0 K, the Einstein temperature and the Debye temperature, a dimensionless constant related to the electron–phonon coupling as well as an effective and a cut-off phonon energy have been estimated. It was found that the major contribution of phonons to the shift of E_g versus T in CuGa₃Se₅ is mainly from optical phonons. The optical absorption coefficient just below the absorption edge varies exponentially with photon energy indicating the presence of Urbach's tail. It was shown that the static structural disorders contribute mainly to the absorption below the direct band gap.

Optical and photovoltaic (PV) properties of PV cells with the structure indium tin oxide (ITO)/C₆₀/conducting polymer (CP)/Au have been investigated. The C₆₀/CP heterojunctions in the PV cells were fabricated by spin-coating an organic solution of CP onto the C₆₀ underlying layer. Mixed organic solvents of chloroform and toluene were used to fabricate C₆₀/CP interpenetrating interfaces. The C₆₀/CP interfaces were controlled by adjusting the mixture ratio of chloroform to toluene. From the optical properties and SEM observation of C₆₀/CP heterojunctions, it has been clarified that the interpenetrating interface of C₆₀ and CP contributes to the balance of carrier generation and carrier transport, resulting in superior PV performance.

Conventional S20 multialkali photocathodes have a wide wavelength coverage from < 200 to > 850 nm, but their high transparency and the surface work function result in low quantum efficiencies at longer wavelengths. Theoretical modelling of the photon and excited electron interactions that define the cathode performance provides a realistic prediction of the measured response. The theory emphasizes that the basic light absorption is strongly sensitive to the cathode thickness, wavelength, polarization and incident angle. Parameters can be selected which predict that even at long wavelengths (e.g. 900 nm), absorption may be increased from ∼1% to ∼100%. Cathode topographies can be designed to exploit these responses and offer increased absorption at the longer wavelengths. Alternative designs, which include waveguiding of light within the cathode window, or in structured surfaces, can similarly lead to almost total absorption of the incident light by increasing the number of interactions. These concepts of optimal incidence and waveguiding have been both theoretically modelled and demonstrated in newly fabricated cathode designs. The methods have variously reached quantum efficiencies in excess of 50% at wavelengths in the range from 200 to > 750 nm under different operational conditions. The improvement factors relative to normal incidence on planar cathodes increase for longer wavelengths, and examples of 20–50 times by ∼900 nm were noted. Whilst the absolute S20 efficiency values at long wavelengths are still small, the improvements offer a usable sensitivity even beyond 1 µm, as demonstrated by spectroscopy data up to at least 1140 nm.

An extensive x-ray diffraction (XRD) study has been undertaken to examine the influence of two dominant crystallographic orientations of polycrystalline hexagonal CdS films, i.e. (0002) and orientations, on subsequent growths of polycrystalline cubic CdTe films with a (111) preferred orientation because the CdS/CdTe heterostructure plays a crucial role in determining the photovoltaic performance of the CdS/CdTe thin-film solar cells despite a 10% lattice mismatch between CdS and CdTe. XRD measurements for the CdS films fabricated with various fabrication conditions revealed a unique relation between the lattice spacings of (0002) and planes. When the CdS(0002) and/or CdS grain sizes increase, the degree of the (111) preferred orientation of the subsequently grown CdTe, p(111), which is a figure of merit for the highly efficient solar cell, tends to increase, while the lattice spacings of the CdTe(111) plane decreases. Based on these results, the effects of CdS(0002) and CdS grain sizes on p(111) are discussed in conjunction with the decreased CdTe(111) lattice spacings, indicating interdiffusion of S and Te elements at the CdS/CdTe interface, which is effective for reducing the 10% mismatch between CdS and CdTe.

An experimental study of the oxygen plasma jet of an OCP 150 cutting torch marketed by Air Liquide is presented. A fast CCD camera is used to visualize the shock wave geometry at the nozzle exit. Optical emission spectroscopy techniques are used to determine the temperature, the electron number density, the pressure and the fraction of nitrogen in the plasma jet between the nozzle exit and the anode. Measurements are performed in a real cutting configuration and compared with the results of a rotating anode device. The influence of several cutting parameters (voltage, torch velocity and plasma producing gas injection pressure) on the macroscopic properties of the arc is dealt with.

A study of arc–material interaction and energy transfer in the case of plasma cutting is presented. A fast CCD camera moving with the torch is used to estimate the anodic arc root location inside the kerf. Temperature measurements on the cut-front surface and on the kerf edges are performed by infrared pyrometry. Temperature fields inside the workpiece obtained with inserted thermocouples are compared with the theoretical results of an analytical model to estimate heat conduction losses Q_HCL (W) dissipated in the plate. For various sets of operating parameters (voltage, inlet oxygen pressure and cutting speed), a complete energy balance of the process is performed with the calculation of the device efficiency on the basis of the various power terms implicated in the cutting tool: the power lost above the workpiece, heat conduction losses, the power involved in melting steel, the energy released by chemical oxidation reactions, the power available for cutting and losses under the plate in the extinguishing plasma.

A Townsend-like barrier discharge in nitrogen at 7 kHz frequency is studied experimentally and theoretically. The discharge is homogeneous under a certain range of parameters, which depends on the material of the barriers. The higher the dielectric permittivity of barriers is, the narrower is this range. It is shown that the discharge properties do not only depend on the total capacitance of barriers but they also explicitly depend on the permittivity of a dielectric sheath near the surface. Measured ranges of existence of a Townsend discharge agree with the calculations based on a self-consistent model. Also, the two-dimensional simulations of the barrier discharge show that the stability of the discharge relative to radial fluctuations may depend on the permittivity of barriers. The effect of barrier material is interpreted as the influence of dielectric permittivity on the electric field induced by surface charges.

Femto-second radiation pulses are becoming an important tool for studying the dynamics of materials at an atomic level. Various methods of generating femto-second electron pulses have been developed, including a thermionic rf gun combined with an alpha magnet. In this paper, we focus on the utilization of a photo-cathode rf gun and an rf linear accelerator to generate far-infrared (FIR) radiation. We demonstrate that with a magnetic chicane the electron beam pulse can be compressed to less than rms 20 fs at an energy between 30 and 50 MeV. Geometrical wake fields due to the rf linear accelerator and the coherent synchrotron radiation effects in the magnetic chicane are included in the study. We suggest a possible improvement of the existing 80 MeV rf linear accelerator at the Pohang Accelerator Laboratory to employ it as a coherent FIR radiation source. We focus on extending the radiation wave number to greater than 1500 cm⁻¹ with a micro-pulse energy of more than 100 µJ, which are the conditions required for femto-dynamics studies.

Atmospheric pressure discharges are routinely used to functionalize rough surfaces of commodity polymeric materials to enhance surface properties. High value polymeric materials, such as scaffolding for tissue engineering, must also have their surfaces treated to achieve similar functionality. The techniques used to achieve this functionality are typically costlier than the commodity processes used for bulk, web treatment of polymer sheets. The issue we are investigating is whether inexpensive, commodity plasma processes can be adapted to treat high value materials while considering the uniformity of processing on micro- and macro-scales. To address these issues a two-dimensional plasma hydrodynamics-surface kinetics model was developed and applied to the investigation of atmospheric pressure plasma functionalization of a polypropylene surface having microstructure using He/O₂/H₂O mixtures. Non-uniformities in functionalization occur over both macroscopic and microscopic length scales and can be controlled by a judicious choice of O₂ fraction.

Metal–halide lamps have high efficiencies. These lamps often contain rare-earth additives (in our case dysprosium iodide) which radiate very efficiently in the visible spectrum. Colour separation is a problem in these lamps; this is caused by axial segregation of these additives as a result of diffusion and convection. To vary the effect of convection, parabolic flights were performed with micro-gravity (0g) and hyper-gravity (∼1.8g) phases. During these flights, the atomic dysprosium density was measured by means of laser absorption spectroscopy. In addition, the lamp voltage, which is strongly influenced by the total amount of Dy in the lamp, was measured. The Dy density and axial segregation are dependent on the gravity. The dynamic lamp behaviour during the parabolas was investigated: the dysprosium density and lamp voltage followed the gravity variations. When entering the micro-gravity phase, the axial diffusion time constant is the slowest time constant; it is proportional to the mercury pressure in the lamp.

A unified transport model for the bulk of a non-equilibrium low-temperature plasma is presented which consists of a fluid description of the heavy particles (neutrals and ions) in local thermal equilibrium, a reduced kinetic equation for the electrons and the assumption of quasi-neutrality. The transport model of the heavy particles is derived by approximately solving a linearized multi-component Boltzmann equation with the help of an expansion into tensorial Hermitian polynomials, while the electron model is taken from the literature. The description accounts for drift, ordinary diffusion and thermal diffusion, as well as for the effects of heat conduction and viscosity. The relation of the model to previously formulated transport theories is discussed and estimates for its range of validity are given.

A microplasma is generated in the microhole (200–400 µm diameter) of a metal–dielectric–metal sandwich (microhollow cathode type) at medium pressure (50–100 Torr) in pure argon. At low discharge current (I < 0.1 mA), the plasma is stable and confined inside the hole. At higher current (I > 0.8 mA), the plasma is also stable and expands on the cathode backside region. For intermediate current, the plasma is self-pulsed at a frequency ranging from a few tens to a few hundreds of kilohertz depending on the averaged discharge current and scales as a linear function of the product pD (pressure × hole diameter).

Reflectance spectrum calculations for a silicon oxynitride (SiO_xN_y)–porous silicon (PS) double layer antireflection coating is performed using the matrix method. The results are compared with the corresponding spectrum of diamond-like carbon (DLC)/PS and SiO₂/TiO₂ double layer coatings. A lower reflectance in the visible and infrared regions of the solar spectrum for the SiO_xN_y/PS double layer is obtained, especially in the 450–600 nm spectral range (with a flat reflectance response remaining as low as ≈0.01%), which corresponds to the maximum intensity of solar irradiation. These findings are of importance in solar cell applications.

Indentation methods can be used to simulate many of the damage processes observed in the erosion testing of bulk materials and coatings. For brittle materials the transition between erosion regimes may be predicted based on simple indentation–derived models. However, the prediction of erosion rates from indentation data presents a greater challenge. In this paper the use of work of indentation to characterize the energy dissipated in damage processes is discussed and this is used to predict erosion behaviour. Reasonable agreement with experimental data is observed in some specific cases.

BaZr_0.15Ti_0.85O₃ thin films were deposited on Pt-coated Si substrates using the pulsed excimer laser ablation technique. X-ray diffraction and atomic force microscope techniques were used to study the structural characteristics of the films. Films with good crystalline quality, with an average grain size of 0.5 µm were obtained, under various oxygen background pressures. Ferroelectric hysteresis loops recorded on the films deposited at 26.66 Pa oxygen pressure showed the best properties. To gain a further understanding of the electrical properties of these films, impedance spectroscopy was used and data acquired at several different temperatures. AC conductivity plots showed the presence of space charge conduction at low frequencies; however, at high frequencies, all the curves merged and expectedly showed an almost dc conduction behaviour. The activation energy obtained from ac conductivity data may be attributed to oxygen vacancy motion.

Alumina-based grinding wheels are dressed by modifying the surface of the wheels through laser surface melting and solidification with laser powers of 500 W (343 J cm⁻²), 750 W (514 J cm⁻²) and 1000 W (686 J cm⁻²) with an irradiation time of 14.4 ms. The rapid solidification rate associated with laser processing results in significant refinement of the surface grains characterized by well-defined regular facets and vertices. Such microstructures are helpful in finish/micro-scale grinding applications. In order to predict the microstructure from the laser processing parameters and the thermo-physical properties of materials, a one dimensional heat flow model is proposed. The effective thermal conductivity of the porous alumina ceramic, which is incorporated in the heat flow model, is calculated using fractal dimensions from analytical correlations. The proposed thermal model predicts the general trend of increasing melt depth with increasing laser power, which is in reasonable agreement with experimental observations. Also, the cooling rates are derived from the thermal model by calculating the values of the temperature gradient (G) at the solid/liquid interface and the velocity of the solid/liquid interface. The calculated values of the cooling rate decrease with increasing laser power in agreement with the established values in the literature. An attempt is made to correlate the observed secondary dendrite arm spacing with the calculated cooling rates.

The molecular flow in the hot wall epitaxial system has been studied by computer simulation using the Monte Carlo technique for the deposition of CdTe thin films. The number of wall collisions, intermolecular collisions, direct transmissions, number of molecules and flux density distributions along each volume of the tube, with different source temperatures and wall temperatures for various lengths and radii of the hot wall setup, have been simulated, then the optimal deposition conditions for the thermodynamic equilibrium of vapour transport are determined and experimentally validated.

This paper reports on the result of space charge evolution in cross-linked polyethylene (XLPE) planar samples approximately 220 µm thick. The space charge measurement technique used in this study is the pulsed electroacoustic method.

There are two phases to this experiment. In the first phase, the samples were subjected to dc 30 kV_dc mm⁻¹ and ac (sinusoidal) electric stress levels of 30 kV_pk mm⁻¹ at frequencies of 1, 10 and 50 Hz ac. In addition, ac space charge under 30 kV_rms mm⁻¹ and 60 kV_pk mm⁻¹ electric stress at 50 Hz was also investigated. The volts-off results showed that the amount of charge trapped in XLPE sample under dc electric stress is significantly bigger than samples under ac stress even when the applied ac stresses are substantially higher.

The second phase of the experiment involves studying the dc space charge evolution in samples that were tested under ac stress during the first phase of the experiment. Ac ageing causes positive charge to become more dominant over negative charge. It was also discovered that ac ageing creates deeper traps, particularly for negative charge.

This paper also gives a brief overview of the data processing methods used to analyse space charge under ac electric stress.

We present results of a theoretical and experimental investigation into monolayers made of oxidized nanogranules of amorphous copper and their aggregates with a high surface concentration. We show theoretically that the packing density of the nanogranules, the size of aggregates, and the thickness and composition of the oxide layer over a Cu nanogranule affect the shift in the plasma resonance. Experimentally we established a non-monotone dependence of the absorption in the plasma resonance band and the UV spectral range with a high surface packing density of copper nanoparticles. The optical measurements indicated a non-uniform oxidation of the granules on the substrate.

It is found that mixtures between iso- and n-pentane have a minimum in the melting line for a composition of 5 : 1 iso/n-pentane. At ambient pressure, this liquid transforms from a viscous fluid to a clear solid between ∼95 K and ∼85 K. We report measurements of the solidification line and approximate viscosity values of this mixture up to 3 kbar in the temperature range 90–130 K using the 'blocked capillary' technique. The results suggest that the 5 : 1 iso/n-pentane mixture may have important applications as a cryogenic hydraulic liquid as well as a pressure transmitting medium in low temperature research.

In any investigation, information about the molecules under consideration is very essential for tailoring their properties. Evaluation of dispersion parameters, namely optical dielectric constant, static dielectric constant, relaxation time and spreading factor, assumes significance in this context. Dielectric spectroscopy is a useful tool for estimating these parameters. Not only does it reveal details about these constants but it also gives insight into the mechanism of conduction. In this paper the evaluation of dispersion parameters of cobalt phthalocyanine tetramer in the temperature range 300–393 K is attempted using Cole–Cole plots. The temperature variation of the spreading factor indicates the existence of multiple equilibrium positions in the case of cobalt phthalocyanine tetramer. To the best of our knowledge, the evaluation of dispersion parameters for cobalt phthalocyanine tetramer is reported for the first time.

The effects of copper oxide additive on the densification, microstructural morphology and nonlinear electrical properties of tin oxide-based varistors are investigated. It is found that copper oxide significantly improves the densification of tin oxide ceramics, while excess copper reduces the densification. Copper oxide partially centralizes at the grain boundaries and partially evaporates at sintering, while tantalum improves the conductivity of the grains. All the samples have excellent nonlinear electrical properties and the sample doped with 0.25 mol% CuO possesses the highest density, the highest nonlinearity coefficient (α = 37.7) and the lowest leakage current density (J_L = 12.6 µA cm⁻²) among all the samples. The copper oxide intergranular insulating layer separates the two semiconductive tin oxide grains and forms barriers.

Zinc oxide (ZnO) nanorods were fabricated by a hydrothermal reaction in ammonia and zinc chloride solution without any surfactant at 95 °C in a sealed bottle. In the area near the solution surface, the product presented urchin-like arrays composed of needle-tipped nanorods with about 40 nm diameter. In the middle and the bottom of the solution, the ZnO nanorods grew vertically on the substrate and showed tapered and flat ends and bigger diameters of about 300–400 nm. The microstructure characterization of x-ray diffraction and high resolution transmission electron microscopy images demonstrated that all ZnO nanorods grew along the [0001] direction. The influence of the chemical reactions and the depth-dependent growth along various facets of ZnO are discussed.

One of the methods of solving the computational complexity of image-processing is to perform some low-level computations on the sensor focal plane. This paper presents a vision system based on a smart sensor. PARIS1 (Programmable Analog Retina-like Image Sensor1) is the first prototype used to evaluate the architecture of an on-chip vision system based on such a sensor coupled with a microcontroller. The smart sensor integrates a set of analog and digital computing units. This architecture paves the way for a more compact vision system and increases the performances reducing the data flow exchanges with a microprocessor in control. A system has been implemented as a proof-of-concept and has enabled us to evaluate the performance requirements for a possible integration of a microcontroller on the same chip. The used approach is compared with two architectures implementing CMOS active pixel sensors (APS) and interfaced to the same microcontroller. The comparison is related to image processing computation time, processing reliability, programmability, precision, bandwidth and subsequent stages of computations.

It is pointed out that an extra process must be taken into account for a correct interpretation of the experimental measurements reported by Paris et al (2005 J. Phys. D: Appl. Phys.38 3894). The analysis presented here allows partial use of the results of the above-mentioned paper with some limitations.

This note compares experimental reflectivity values of CdTe with those calculated from the corrected equation in a previous comment, which replaced a wrongly typed equation in three previously published papers.